| Acronym | Organisation | Country | Notes | |
| ABS | American Bureau of Shipping, Ship classification association | USA | USA | |
| ABS | American Bureau of Shipping USA Ship classification association | USA | ||
| Acronym | Name | Continent/country | Notes | |
| AEI | Assoziazione Elettrotechnica ed Elettronica Italiana Italy; Italian electrotechnical industry organisation | Italy | Italy | |
| AENOR | Asociacion Española de Normalización y Certificación,Spanish organisation for standards and certification | Spain | Spain | |
| AFSEC | African Eletrotechnical Standardisation Commission | 28/02/2008 | ||
| AIEE | American Institute of Electrical Engineers(usa) | USA | ||
| ALPHA | Gesellschaft zur Prüfung und Zertifizierungvon Niederspannungsgeräten German.test laboratories association | Germany | Germany | |
| ANCE | Asociación de Normalización y Certificación, A.C. | Mexico | I think (cause I can't read Mexican- they dont have an english website) Standards Association for Mexico) | |
| ANSI | American National Standards Institute | USA | USA | |
| ANSI | American National Standards Institute | USA | ||
| AS | Australian Standard Australia | Australia | ||
| ASA | American Standards Association,American association for standards | USA | USA | |
| ASTA | Association of Short-Circuit Testing Authorities,Association of the testing authorities | UK | Great Britain | |
| ASTA | Association of Short-Circuit Testing Authorities Association of the testing authorities | Great Britain | ||
| BEC | British Electrotechnical Commission | UK | ||
| BS | British Standard | UK | Great Britain | |
| BS7671 | The Institution of Engineering and Technology(BS) | UK | British Electrical code, BS 7671 (the IET Wiring Regulations) sets the standards for electrical installation in the UK and many other countries. The IET co-publishes the Regulations with the British Standards Institution (BSI) and is the authority on electrical installation. Organisation = IET Wiring Regulations: British Standard BS 7671 "UK Requirements for Electrical Installations. ", (“The Regs"), covering domestic, commercial, industrial, and other buildings, marinas, caravan parks and other special installations and locations. Up to and including 1000Vac and 1500Vdc. Wiring standards in UK: 230Vac, 50. Apparantly also used in countries: Mauritius, St Lucia, Saint Vincent and the Grenadines, Sierra Leone, Sri Lanka, Trinidad and Tobago, Uganda, Cyprus, and others. |
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| BSI | British Standards Institution | UK | ||
| BV | Bureau Veritas | Ship´s classification association | ||
| CANENA | Council for the Harmonization of Electromechanical Standards of the Nations of the Americas | USA + Canada | ||
| CE | Europe | The CE Mark identifies a product as complying with the health and safety requirements spelled out in European legislation (Directives) and is mandatory for equipment operating in the European Union (EU). Once the product has received the CE Mark it can circulate freely throughout the European Union countries. | ||
| CEBEC | Comité Electrotechnique Belge, Belgian electro-technical product quality mark | Belgium | Belgium | |
| CEC | Canadian Electrical code | Canada | The Canadian Electrical Code, CE code, or CSA C22.1 is a standard published by the Canadian Standards Association pertaining to the installation and maintenance of electrical equipment in Canada. The first edition of the Canadian Electrical Code was published in 1927.[1] The current (23rd) edition was published in 2015.(Wiki). Technical requirements of the Canadian Electrical Code are very similar to those of the US National Electrical Code. Specific differences still exist and installations acceptable under one Code may not entirely comply with the other. Correlation of technical requirements between the two Codes is ongoing. Several CEC Part II electrical equipment standards have been harmonized with standards in the USA and Mexico through CANENA, The Council for the Harmonization of Electromechanical Standards of the Nations of the Americas (CANENA) is working to harmonize electrical codes in the western hemisphere. |
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| CEC | The Canadian Electrical Code, CE code, or CSA C22.1 is a standard published by the Canadian Standards Association pertaining to the installation and maintenance of electrical equipment in Canada. The first edition of the Canadian Electrical Code was published in 1927.[1] The current (23rd) edition was published in 2015.(Wiki). Technical requirements of the Canadian Electrical Code are very similar to those of the US National Electrical Code. Specific differences still exist and installations acceptable under one Code may not entirely comply with the other. Correlation of technical requirements between the two Codes is ongoing. Several CEC Part II electrical equipment standards have been harmonized with standards in the USA and Mexico through CANENA, The Council for the Harmonization of Electromechanical Standards of the Nations of the Americas (CANENA) is working to harmonize electrical codes in the western hemisphere. |
Canada | ||
| CEI | Comitato Elettrotecnico Italiano Italian standards organisation | Italy | Italy | |
| CEI | Commission Electrotechnique Internationale International electrotechnical commission | Switserland | Switzerland | |
| CEMA | Canadian Electrical Manufacturers’ Association, Verband der Kanadischen Elektroindustrie | Canada | Canada | |
| CEN | Comité Européen de Normalisation, European standards committee | Europe | Europe | |
| CENELEC | European Committee for Electrotechnical Standardisation | Europe | ||
| CSA | Canadian Standards Association | Canada | Organisation = Canadian Standards Association: The Canadian Electrical Code, CE code, or CSA C22. Started: 1927. Three-year cycle. Participitants are volunteers from industry and government. A reference indicated that its not a law book but a “prescriptive model” – other methods an be used as long as its approved by the repsective authority. Interesting? Also it is regionally based Also: Since the Code is a copyrighted document produced by a private body, it may not be distributed without copyright permission from the Canadian Standards Association. Why earth would anyone – for whatever reason – not make a book of such great importance available to all. Why? So what if we copy the damn thing…what can we do? |
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| CSA | Canadian Standards Association Canadian standards association | Canadian standard | ||
| DEMKO | Danmarks Elektriske Materielkontrol | Denmark | Danish material control for electrotechnical products | Denmark |
| DENAN | Japan | Japan | A mandatory national law administered by Japan’s METI (Ministry of Economy, Trade and Industry) | |
| DENTORI | Electrical Appliance and Material Control Law(Japan -former) | Japan | ||
| DGN | DGN (Dirección General de Normas) in the electrical sector and household appliances which developes Mexican Standards (NMX) | Mexico | ||
| DIN | Deutsches Institut für Normung | Germany | German institute for standardisation | Germany |
| DNA | Deutscher Normenausschuss German standards committee | Germany | ||
| DNV | Det Norsk Veritas Ship classification association | Norway | Ship classification association | |
| ECA | Electrical Contractors Association | South Africa | ||
| ECQAC | Electronic Components Quality Assurance Committee | Committee for components with a verified quality | Europe | |
| ELOT | Hellenic Organization for Standardization Greek organization for standardization | Greece | ||
| EMA | EMA (Entidad Mexicana de Acreditación) in order to certificate a variety of products. | Mexico | ||
| EN | European standard | Europe | Europe | |
| EOTC | European Organization for Testing and Certification | Europe | Europäische Organisation für Konformitätsbewertung | Europe |
| ETCI | Electrotechnical Council of Ireland | Irish | Irish organization for standardization | Ireland |
| ETL | Intertek Group(US) | USA | Intertek and ETL Semko. Intertek (www.intertek-etlsemko.com). They are a Nationally Recognized Testing Laboratory and tests products to UL, CSA and CE standards. The mark indicates that the manufacturer's production site conforms to a range of compliance measures and is subject to periodic follow-up inspections to verify continued conformance. An ETL Listed mark with both "us" and "c" identifiers signifies that the product bearing the mark complies with both UL and CSA product safety standards. If it bears just the "us" identifier, it has been tested and deemed compliant to UL. product safety standards only. An ETL Listed mark with a "c" identifier means the product bearing it complies with CSA product safety standards only. |
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| EU | European Union | Europe | The European Union (consisting of Austria, Belgium, Denmark, Cyprus, Czech Republic, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden and the United Kingdom) has set up rules for selling certain types of products within the EU. For example, there are rules for medical devices, machines with moving parts, electronic devices, etc. If you want to sell a product in one of these categories anywhere in the European Union, your product must meet the standards set by the rules. If your product meets the standards, it can bear a CE marking and be sold in the EU. CE stands for Conformité Européenne, which is French for "European Conformity." A product in one of the controlled product categories cannot legally be sold in the EU unless it has passed the tests to receive the CE marking. For a company trying to sell a product, getting a CE marking makes things much easier because it means you can sell the product anywhere in the EU. In the United States, electronic device manufacturers need to meet the same sort of requirements to get FCC approval. |
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| FM | FM Approvals(US) | USA | ||
| GL | Germanischer Lloyd Ship classification association | Germany | ||
| HD | Harmonization document Europe | Europe | ||
| HD | Harmonization document | Europe | ||
| IEC | International Electrotechnical Commission | International | International voting on the content of standards for worldwide standardisation. Each member body country may submit proposed modifications of existing standards and request for new standards. The abbreviation IEC stands for “International Electrotechnical Commission“. The commission is based in Geneva. Germany is one of the few industrial countries that are leading in the field of standardisation. After acceptance of the standard by the member countries, each country is allowed to harmonise it in a national version. |
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| IEC | International Electrotechnical Commission | International | International Electrotechnical Commission | |
| IEE | Institute for Electrical Engineers | UK | Merging with Inst. Of Incorporated Engineers(IIE) to become the IET Inst. Of Engineering and Technology (2006) – seems that any one in the world can join. Probably have to meet some min. criteria? | |
| IEEE | Institute of Electrical and Electronics Engineers. (usa) | USA | AIEE (which merged with IRE to form IEEE in 1963) | |
| IET | The Institution of Engineering and Technology(BS) | UK | ||
| IEV | International Electrotechnical Vocabulary | |||
| IPQ | Instituto Portoguês da Qualidade Portuguese quality institute | Portugal | ||
| IRC | International Residential Code(US) | USA | Spawned from NEC | |
| ISO | International Organization for Standardization Internationale Organisation für Normung | International | ||
| Italian standards organisation | Italy | |||
| ITU | ||||
| JEM | Japanese Electrical Manufacturers Association Electrical industry association | Japan | ||
| JIC | Joint Industry Conference Gesamtverband der Industrie | USA | ||
| JIS | Japanese Industrial Standard | Japan | ||
| KEMA | Keuring van Elektrotechnische Materialen Testing institute for electrotechnical products | Netherlands | ||
| LOVAG | Low Voltage Agreement Group | International | ||
| LRS | Lloyd's Register of Shipping Ship classification association | Great Britain | ||
| MET | MET Laboratories(US) | USA | ||
| MITI | Ministry of International Trade and Industry | Japan | ||
| NBN | Norme Belge | Belgian standard | ||
| NEC | National Electrical Code(USA) | USA | Despite the use of the term "national", it is not a federal law. It is typically adopted by states and municipalities in an effort to standardize their enforcement of safe electrical practices.[2] In some cases, the NEC is amended, altered and may even be rejected in lieu of regional regulations as voted on by local governing bodies. First published in 1897, the NEC is updated and published every three years. The 2014 NEC is the current edition (effective date needed) Part of the NFPA.See attached doc for which states has adopted NEC. | |
| NEC | National Electrical Code | USA | Organisation: ANSI; National Fire Protection Association; Code: National Electrical Code (NEC), or NFPA 70. Also a “guide” or refrence or even code of good practice it seems to me, and not law. Each state have the option to accept it, ammend it opr reject it. I have read some states might not accept a new code and still abide by codes of previous years. 5 years cycle. They have an inpectorate called "Authority Having Jurisdiction" The inspects for compliance with these minimum standards.[3][4] Started: 1897, I am no expert in their copy right laws but their code is pretty readily available online |
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| NEMA | National Electrical Manufacturers Association(USA) | USA | ||
| NEMA | National Electrical Manufacturers Association Electrical industry association | USA | ||
| NEMKO | Norges Elektrische Materiellkontroll;Norwegian testing institute for electrotechnical products | Norway | ||
| NEN | Nederlands Norm; Dutch standard; Netherlands NFPA National Fire Protection Association US-amerikanische Gesellschaft für Brandverhütung | USA | ||
| NFPA | National Fire Protection Association(USA) | USA | A private trade association. | |
| NICEIC | National Inspection Council for Electrical Installation Contracting | USA | ||
| NKK | Nippon Kaiji Kyakai Japanese classification association | Japan | ||
| NRTLs | Approved by the United States Department of Labor | USA | ||
| OSHA | Occupational Safety and Health Administration (US) | USA | ||
| ÖVE | Österreichischer Verband für Elektrotechnik | Austria | Austrian electrotechnical association | Austria |
| PEHLA | Prüfstelle elektrischer Hochleistungsapparate der Gesellschaft für elektrische Hochleistungsprüfungen Electrical high-performance apparatus test laboratory of the association for electrical high-performance testing | Germany | ||
| PSE | Product Safety Electrical Appliance & Material (Japan) | Japan | ||
| RCAB | Registered Conformity Assessment Body(Japan) | Japan | ||
| TBT | Treaty on Technical Barriers to Trade(WTO) | International | ||
| UL | Underwriters Laboratories(US): How does the US acceptance procedure for electrical plants work? Every piece of electrical equipment (machine/plant) is tested by the competent local inspector (AHJ = Authority Having Jurisdiction) prior to commissioning. The AHJ has the final say with regard to commissioning. All AHJs use Standard NFPA 70 (NFPA = National Fire Protection Association) as a basis, which is generally regarded as the NEC (National Electrical Code). The AHJ considers the use of UL-recognized or UL-listed components an important indication that a system complies with the safety requirements to NFPA 70. This saves time and money during construction and commissioning of the equipment, as the UL symbol indicates that testing of the components and/or of the system did not reveal any foreseeable risks with regard to fire, electric shock and associated dangers. For appliances with recognized labelling, the UL inspector inspects the COAs he can see in the UL-file. |
USA | World's largest, not-for-profit product safety testing and certificationorganization with global name recognition and acceptance. Founded in 1894 in the US, it permits the use of its listing mark (the UL mark) as its stamp of approval on goods and materials after standardized and stringent testing. Thereafter its inspectors regularly visit the producer to audit compliance with its certification requirements. UL has some 46 laboratories and 200 inspection centers in over 70 countries and applies its 750 standards to more than 18 thousand types of products manufactured by about 60 thousand firms. UL mark, however, guarantees only the safety of the item in use, not its performance or quality.UL stands for Underwriters Laboratories, an organization that has been around for more than 100 years. If you visit the UL Web site at www.ul.com, you can find the following description: "UL is a world leader in product safety testing and certification. For more than 100 years, manufacturers have had their merchandise evaluated and tested for safety risks by our independent, third-party safety certification organization. Last year alone, approximately 14 billion products with the UL Mark entered the global marketplace." A good nine-word summary used by UL is, "A not-for-profit organization dedicated to public safety." UL sets standards for different product categories and tests products to make sure they meet the standards. In this way, UL is similar to the CE marking organization. UL may also certify the installation of products in the field. Underwriters, by the way, are insurers. According to Encyclopedia Britannica, "The word underwriter is said to have derived from the practice of having each risk taker write his name under the total amount of risk that he was willing to accept at a specified premium." |
When labelling UL-approved products, a general distinction is made between Recognized Components and Listed Components: Recognized Components This label is used on products that are not complete in terms of their application. These products are listed in the UL’s “yellow component database”. The correct use of such components must make due allowance for the “Conditions of Acceptability”, listing the framework conditions and application parameters approved by the UL. These may be deratings, application/use specifications in conjunction with additional active/passive components, as for example specific fuse types. Furthermore, the application field of “branch circuits“ or “feeder circuits“ of the component is determined by the COAs. Listed Components This symbol is used in products that offer a complete function in themselves. Without consideration of the COAs. These products are listed in the UL’s “green component database”. They may be used without restriction in accordance with the tested rating. For this all technical data must be visible on the type plate. Separate assembly instructions must be directly attached to the device or allocated to the product on a package insert. |
| WTO | World Trade Organization . | International | ||
| ECQAC | Electronic Components Quality Assurance Committee Committee for components with a verified quality | Europe | ||
| Europe |
| Name | Symbol | Represented by: | Definition | Unit for: | Name | Symbol | Represent | Definition | Unit for: | |||
| Ampere (amp) | A | A current of 1amp is flowing if: -In a vaccum, two infinitely long conductors of neglible circular cross section is placed parallel 1meter apart and a force between the coductors equal to 2 x 10e7 Newton per meter of length is produced. | Electric current (I) | I = V ÷ R | Time – Second | s | The duration of 192 631 770 cycles of radiation corresponding to the caesium atom -133 atom | Time (t) | ||||
| Volt – Definition | The difference of electrical potential between two points on a conductor when a current of 1Amp flows and the power dissipated is 1Watt. | Voltage (V, E) Electromotive force (E) Potential difference (??) |
V = I × R | |||||||||
| Ohm Definition | R or Ω | For a purely resistive conductor (does not generate any electromotive force) if 1 volt is applied and the current flow is 1Amp then the conductor resistance will be 1 Ohm. | R = V ÷ I | |||||||||
| Watt | W | Electric power (P) | Meter / metre | m | Length (l) | |||||||
| Decibel-milliwatt | dBm | |||||||||||
| Decibel-Watt | dBW | |||||||||||
| Volt-Ampere-Reactive | var | Q | Reactive power (Q) | Square-meter | m2 | Area (A) | ||||||
| Farad | F | Capacitance (C) | Terra | T | 1000000000000 | 10e12 | ||||||
| Henry | H | The inductance of a closed circuit in which an emf of 1V is produced when the electric current in the circuit varies uniformly at 1A/second | Inductance (L) | 'VL = -L(di/dt) | Giga | G | 1000000000 | 10e9 | ||||
| siemens / mho | S | Conductance (G) Admittance (Y) |
Mega | M | 1000000 | 10e6 | ||||||
| Ampere-hour | Ah | Electric charge (Q) | kilo | k | 1000 | 10e3 | ||||||
| Joule | J | Energy (E) | none | none | 1 | |||||||
| Watt | W | P | A power equal to 1J/s | 'P = V × I or I2 × R | centi | c | 1/100 | 10e2 | ||||
| Watt-hour | Wh (kWh) | Energy (E) | milli | m | 1/1,000 | 10e3 | ||||||
| Electron-volt | eV | Energy (E) | micro | µ | 1/1,000,000 | 10e6 | ||||||
| Ohm-meter | ??m | Resistivity (?) | nano | n | 1/1,000,000,000 | 10e9 | ||||||
| Siemen | G or ℧ | G = 1 ÷ R | pico | p | 1/1,000,000,000,000 | 10e12 | ||||||
| siemens per meter | S/m | Conductivity (?) | ||||||||||
| Volts per meter | V/m | Electric field (E) | ||||||||||
| Newtons per coulomb | N/C | Electric field (E) | ||||||||||
| Volt-meter | V?m | Electric flux (?e) | ||||||||||
| Tesla | T | Magnetic field (B) | ||||||||||
| Gauss | G | Magnetic field (B) | ||||||||||
| Weber | Wb | Is the magnetic flux when linking a circuit of 1 turn produces an emf of 1Volt in it, when it is is uniformly reduced to zero over 1sec. | Magnetic flux (?m) | |||||||||
| Tesla | T | Magnetic flux density at 1 Wb/m2 | ||||||||||
| Hertz | Hz | F | Cycles per second | Frequency | 'ƒ = 1 / T | |||||||
| Charge | Q | Q = C × V | ||||||||||
| Decibel | dB | |||||||||||
| Parts per million | ppm | |||||||||||
| Coulomb | C | The quantity of electricity transported in 1 second by 1 amp. | Electric charge | C = Q ÷ V | ||||||||
| Farad. | F | The capacitance between two plates with potential difference of 1 volt when it is charged with 1C (coulomb) | Capacitance | |||||||||
| Impedance | Z | Z | Impedance | Z2 = R2 + X2 | ||||||||
| Newton | N | N | A newton is a force when applied to a mass of 1kg will accelerate it at 1m/s | |||||||||
| Pascal | Pa | Pa | A pressure equal to 1N./m2 | |||||||||
| Joule | J | J | The work done when a force of 1N is exerted through a distance of 1mtr in the direction of the force. | |||||||||
| Lumen | lm | lm | The luminous flux emitted within unit solid angle by a point source having a uniform intensity of 1 candela. | |||||||||
| Lux | lx | lx | an illuminance of 1m/m2 | |||||||||
| Name | Acronym | Description | Reference | Standard (NEC=UL) | Others | ||||
| CB: miniature circuit breaker | MCB | Miniature circuit breaker - 0.5 to 125Amp, | IEC | ||||||
| CB: Short-circuit protective device - device intended to protect a circuit or parts of a circuit against short-circuit currents by interrupting the current | SCPD | ||||||||
| CB: Molded case circuit breaker | mccb | A circuit breaker having a supporting housing of moulded insulating material forming an integral part of the circuit breaker (IEC 947-2). | NEC | ||||||
| CB: Current: Ampere Interrupting Capacity - | AIC | Overcurrent between normal rated current and the breaking capacity of the breaker |
Abb | IEC | |||||
| CB: earth leakage circuit breaker | ELCB | IEC | |||||||
| Current: Operating current (fuse or circuit breaker) | I2 | IEC | |||||||
| CB: current to operate protective device | Ia | IEC | |||||||
| CB: Current: design current | Ib | IEC | |||||||
| CB: Current: fault current | Id | IEC | |||||||
| CB: Current: The MAXIMUM tripping current value of a circuit breaker. | In | Current: The MAXIMUM tripping current value of a circuit breaker. | IEC | ||||||
| CB: tabulated current | It | Current: tabulated current | IEC | ||||||
| CB: current carrying capacity | Iz | Especially for a cable | IEC | ||||||
| CB: Current setting – the set current of a circuit breaker | Ir | Ir (in A rms) is a function of ln. Ir is known as Long Time Protection (LTP). For an adjustable CB the set tripping current value set as percentage of In (designed max. tripping value)The set |
IEC | ||||||
| CB: | Ind | Ind = 1.05 Ir | IEC | ||||||
| CB: Current: Id is given for a conventional tripping time. | Id | Id = 1.30 Ir. For a current greater than ld, tripping by thermal effect will take place according to an inverse time curve. | IEC | ||||||
| CB: Short time tripping setting current (Isd) | Isd | Isd (in kA rms) is a function of Ir. lsd characterises short-circuit protection. The circuit breaker opens according to the short time tripping curve: |
IEC | ||||||
| CB: Instantaneous tripping setting current (Ii) | Ii (in kA) | is given as a function of ln. It characterises the instantaneous short-circuit protection for all circuit-breaker categories. For high overcurrents (short-circuits) greater than the li threshold, the circuit-breaker must immediately break the fault current. . This protection device can be disabled according to the technology and type of circuit-breaker (particularly B category circuit-breakers). |
IEC | ||||||
| CB: moulded case circuit breaker | MCCB | Molded case cicuit breaker | IEC | ||||||
| Current: prospective short-circuit current | PSC | IEC | |||||||
| CB: residual current circuit breaker | RCCB | or instantaneously (similar to instantaneous protection). | IEC | ||||||
| residual current device | RCD | Isd is known as Short Time Protection or lm | IEC | ||||||
| CB: Air Circuit Breaker | ACB | IEC | |||||||
| Current: Rated conditional short circuit current. | Icc | This is the rating that is associated with a SCPD; the short circuit current will initially flow and then be cleared by the protective device (this test is not given a time duration). Because of the complexities of ensuring appropriate selection is made, the second alternative rating, the Short Circuit Withstand (Icw) is often specified. | IEC | ||||||
| Current: Rated Short Time Withstand Current. | Icw | This is the rating of current that the assembly can withstand for a set period of time without the aid of a SCPD. The rating is made up of 2 parts: the RMS rating in kA and the duration. There is no international standard for the timing, however times of 0.5, 1 and 3 seconds are commonly used. Icw includes the Rated Peak Withstand Current (Ipk), which is a surge of current that occurs on one phase of the system in the first full cycle, as well as the changes of electro-magnetic forces that occur through the number of cycles seen during the test. The number of cycles is dependent on the frequency of the supply and duration of the test. For example, if the test supply is 50Hz and the duration is 3 seconds, there will have been 150 cycles. | IEC | ||||||
| Current: Rated Short Time Withstand Current. | Icw | 4.3.10. Icw Rated Short-Time Withstand Current Circuit-breakers of Selectivity Category B have a short-time delay (STD) allowing time graded selectivity between circuit-breakers in series. Icw is the fault current the circuit-breaker will withstand for the maximum short-time delay time. Preferred times are: 0.05, 0.1, 0.25, 0.5 and 1.0 second. |
Beama | IEC | |||||
| Current: RATED CONTINUOUS CURRENT (Circuit breaker) | The rated continuous current of a circuit breaker is the designated limit of rms current at rated frequency that it shall be required to carry continuously without exceeding the temperature limitations designated in Section 7 (in ANSI C37.13). The preferred continuous current ratings of the various frame sizes are listed in ANSI C37.16-1988. The rated continuous current of a circuit breaker equipped with direct-acting trip devices or fuses of a lower rating than the frame size of the circuit breaker is determined by the rating of those devices. | UL 489, UL 1066, ANSI C37.13 and ANSI C37.17 Standards |
NEC | ||||||
| Voltage: RATED MAXIMUM VOLTAGE: | The rated maximum voltage of a circuit breaker is the highest rms voltage, three-phase or single-phase, at which it is designed to perform. The circuit breaker shall be rated at one or more of the following maximum voltages: 635V, 508V, or 254V. For fused circuit breakers, the 635V rated maximum voltage becomes 600V to match the fuse rating. | UL 489, UL 1066, ANSI C37.13 and ANSI C37.17 Standards |
NEC | ||||||
| Volts: Rated insulatation voltage(> Uemax) | Ui | Hager | IEC | ||||||
| Volts: Rated impulse voltage withstand voltage | Uimp | hager | IEC | ||||||
| Volts: Rated operational voltage voltage | Ue | Hager | IEC | ||||||
| Volts: Rated service voltage | Ue | hager | IEC | ||||||
| Current: : rated residual operating current (often called residual sensitivity) | IΔn | IEC | |||||||
| Temperature rise test | Δt: | IEC | |||||||
| IEC | |||||||||
| Current: SHORT CIRCUIT CURRENT RATING | : the maximum RMS prospective (available) current to which a device can be connected when protected by the specified overcurrent protective devices. The rating is expressed in amperes and volts. |
UL 489, UL 1066, ANSI C37.13 and ANSI C37.17 Standards |
NEC | ||||||
| CB: Current limiting circuit breaker | A cb with break time short enough to prevent the short circuit current reaching it otherwise attainable peak value. | IEC-IEV | IEC | ||||||
| CB: THRESHOLD CURRENT | The RMS symmetrical prospective current at the threshold of the current limiting range, where: a) the peak current let-through in each phase is less than the peak of that symmetrical prospective current, and b) the I2t in each phase is less than the I2t of a 1/2 cycle wave of the symmetrical prospective current. |
Abb | IEC | ||||||
| CB: Thermal-magnetic tripping units. |
TMTU | They consist of two parts: The thermal trip unit – A bimetal thermal strip is made up of dissimilar metals anchored on one end with different contracting properties over temperature. As higher currents is allowed to flow it will heat the metals and a point will be reached when the contacts open. It is also calibrated in time. This takes care of the overload currents in a circuit. This function can be fixed or adjustable in terms of trip value and/or time. a-release Magnetic tripping unit: Consist of a coil and plunger. If the rated current is exceeded by a calibrated (set) multiple the higher energy levels activate the coil plunger opening the contacts - within a specific time frame. This unit provides Short Current Protection. There are breakers manufactured with only one of the functions as an example if only Short Current Protection is required. On the other hand on some breakers certain functions can be disabled to achieve same purpose. This function can be fixed or adjustable in terms of trip value and/or time. N-release |
IEC | ||||||
| CB: Electronic tripping units |
ETU | – Electronic technologies also entered this market. Microprocessors are being employed to do the thinking nowadays. Much more complete control can be achieved and the benefits are endless from communications to monitoring to reporting. I do not think an ACB exist not based on electronic (microprocessor) technolog |
IEC | ||||||
| CB: Nominal trip current indicated on CB. | In | IEC | |||||||
| CB: Rated current setting | Ir | IEC | |||||||
| CB: Short time delay | Isd | IEC | |||||||
| CB: Rated Instantaneous current trip setting | Ii | IEC | |||||||
| CB: Rated Ground fault trip setting g - release |
Ig | IEC | |||||||
| Cb: Short time delay (time) | tsd | IEC | |||||||
| Let through energy - (I squared t) | I2t | I2t -(Amps Squared Seconds) - An expression to indicate the amount of energy as a result of the duration of a fault current flowing through a circuit breaker before it opens the circuit. gs- means my own definition. | IEC | ||||||
| I2t for fuse | The I2t value The amount of energy spent by the fuse element to clear the electrical fault. This term is normally used in short circuit conditions and the values are used to perform co-ordination studies in electrical networks. I2t parameters are provided by charts in manufacturer data sheets for each fuse family. For coordination of fuse operation with upstream or downstream devices, both melting I2t and clearing I2t are specified. The melting I2t, is proportional to the amount of energy required to begin melting the fuse element. The clearing I2t is proportional to the total energy let through by the fuse when clearing a fault. The energy is mainly dependent on current and time for fuses as well as the available fault level and system voltage. Since the I2t rating of the fuse is proportional to the energy it lets through, it is a measure of the thermal damage and magnetic forces that will be produced by a fault. General formulation should be: I2t value of surge current < I2t value of fuse < Maximum allowable fault current I2t |
IEC | |||||||
| Let through energy - (I squared t) | I2t | I2t characteristic of a circuit-breaker information (usually a curve) giving the maximum values of I2t related to break time as a function of prospective current (r.m.s. symmetrical for a.c.) up to the maximum prospective current corresponding to the rated short-circuit breaking capacity and associated voltage | is.iec 60947-2.2003 – 2.18 | IEC | |||||
| Let through energy - (I squared t) | I2t | 4.3.9. Energy let-through (I2t) Energy let-through is not a rated value but is used in the consideration of back-up and selectivity. I2t is a measure of the energy let-through by the circuit-breaker under short circuit conditions. I2t is used at fault current levels where the short time to operate does not lend itself to the use of time current curves. |
Beama pg | IEC | |||||
| Let through energy - (I squared t) | Let Through Energyis the amount of fault energy which passes through a circuit breaker to downstream network measured from the instant the fault occurs in a system to the instant the circuit breaker clears the fault. |
Hager electricians h/book | IEC | ||||||
| CB:ground(earth) fault time delay) | tE | IEC | |||||||
| CB:Current-zero interrupting type of circuit breaker | In the case of an alternating current, the arc is extinguished automatically at ea current zero. This property is employed in the current-zero interrupting type of circuit breakers and the re-striking of the arc is prevented. The path of the arc de-ionised by drawing away the heat-energy. In other words, the charged parti cles or ions are removed from the path across which the arc burned just before its extinction. A re-striking of the arc due to the recovery voltage across the contacts after the current zero is thus prevented. |
Basics of cb AB | IEC | ||||||
| Cb:Special features of the current limiting circuit breaker | In order to reduce the mechanical (due to electro-dynamic forces) and thermal stresses on the object to be protected, the current must be interrupted right during the initiation of the short-circuit, before the full prospective value can be attained (as for example to avoid the welding of the contactor contacts). This is achieved by : • Quick opening of the main contacts. • Rapid build-up of a high arc-voltage (move the arc quickly away from the contact tips and guide it to the arc chamber). |
Basics of cb AB | IEC | ||||||
| Cb: Current limiting range: |
RMS symetrical prospective currents between the threshold current and max. interrupting rating current | Abb | |||||||
| Cb:Short time-delay trip function | Tsd | ||||||||
| CB: Instantaneous trip function | |||||||||
| CB: Ground-fault trip function y | |||||||||
| Cb: Neutral monitoring protection. | N | Most, if not all, adjustable breakers have this setting available as Disable, 50%, 100%. 2. Neutral conductor protection Inverse-time-delay overload releases for neutral conductors are available in a 50% or 100% ratio of the overload release. The neutral must have specific protection if: · It is reduced in size compared to the phases · Nonlinear loads generating third order harmonics are installed It may be necessary to cut off the neutral for functional reasons (multiple source diagram) or safety reasons (working with power off). | |||||||
| Cb: Inverse time: | Indicating a feature where the higher the trip current the quicker the trip delay. | ||||||||
| Cb: Long time pickup - | The exact time point when the long delay is initiated. | ||||||||
| Cb: Long time delay: - | The duration of the overload condition before the cb trips. Gs | ||||||||
| Current: Prospective (Fault) Current: | - The expected fault current that will flow in a circuit under dead short (Neglibly small load impedance) ) conditions. | ||||||||
| Cb: Short time pickup: | The initiating time of a fault current falling under dead short category (on the tripping curve) | ||||||||
| Cb: Short time delay: | The duration of the fault current falling under a dead short category. | ||||||||
| Current: THRESHOLD CURRENT | The RMS symmetrical prospective current at the threshold of the current limiting range, wher: a) the peak current let-through in each phase is less than the peak of that symmetrical prospective current, and b) the I2t in each phase is less than the I2t of a 1/2 cycle wave of the symmetrical prospective current." | Abb | |||||||
| Cb: Fixed Instantaneous release trip(Trip) | - - the part of a over current release element, for a non adjustable cb, that will trip cb instananeously at a predetermined current value. | ||||||||
| Current: Rated uninterrupted current (In | In | The rated uninterrupted current for a circuit-breaker is a value of current, that the circuit-breaker can carry during uninterrupted service. Rated residual operating current (I∆n ) It is the r.m.s. value of a sinusoidal residual operating current assigned to the CBR by the manufacturer, at which the CBR shall operate under specified conditions. |
Abb technical guide | ||||||
| Current: maximum | In | Maximum value of current | Hager | ||||||
| Current: Rated short-circuit capacity (marked on the device), | Icn | Icn is the maximum fault current the breaker can interrupt safely, although the breaker may no longer be usable. |
IEC | BS | BS EN 608981 and BS EN 610091 | ||||
| Current: Service short-circuit capacity. | Ics | Ics is the maximum fault current the breaker can interrupt safely without loss of performance. The Icn value is normally marked on the device in a rectangle, e.g. 6000 |
BS EN 608981 and BS EN 610091 | ||||||
| Current:Rated current | In: rated current = maximum value of current used for the | IEC | BS | BS EN 608981 and BS EN 610091 | |||||
| Current: service short-circuit breaking capacity | Ics | a breaking capacity for which the prescribed conditions according to a specified test sequence include the capability of the circuit-breaker to carry its rated current continuously 2.16 |
IEC | IEV | |||||
| Current: Breaking capacity | The breaking capacity is the maximum current that can safely be interrupted by the fuse. Generally, this should be higher than the prospective short circuit current. Miniature fuses may have an interrupting rating only 10 times their rated current. Some fuses are designated High Rupture Capacity (HRC) and are usually filled with sand or a similar material. Fuses for small, low-voltage, usually residential, wiring systems are commonly rated, in North American practice, to interrupt 10,000 amperes. Fuses for larger power systems must have higher interrupting ratings, with some low-voltage current-limiting high interrupting fuses rated for 300,000 amperes. Fuses for high-voltage equipment, up to 115,000 volts, are rated by the total apparent power (megavolt-amperes, MVA) of the fault level on the circuit. | ||||||||
| Current: Rated service breaking capacity(*) (Ics) | Ics | Ics (kA rms) is given by the manufacturer and is expressed as a % of Icu. This performance is very important as it gives the ability of a circuit-breaker to provide totally normal operation once it has broken this short-circuit current three times. The higher Ics, the more effective the circuit-breaker. |
Schneider | ||||||
| Current: ultimate short-circuit breaking capacity | Ius | a breaking capacity for which the prescribed conditions according to a specified test sequence do not include the capability of the circuit-breaker to carry its rated current continuously 2.15.2 |
IEC | IEV | |||||
| Current: Rated ultimate short-circuit breaking capacity | Icu | 4.3.5.2.1 The rated ultimate short-circuit breaking capacity of a circuit-breaker is the value of ultimate short-circuit breaking capacity (see 2,1 5,1) assigned to that circuit-breaker by the manufacturer for the corresponding rated operational voltage, under the conditions specified in 8,3.5. It is expressed as the value of the prospective breaking current, in kA (r, m.s. value of the a.c. component in the case of a,c. ), | is.iec 60947-2.2003 – 2.17.4 | IEC | |||||
| Current: short-circuit breaking (or making) capacity | a breaking (or making) capacity for which the prescribed conditions include a short circuit 2.15.1 |
IEC | IEV | ||||||
| Current: Rated ultimate breaking capacity(*) (Icu) | Icu | Icu (kA rms) is the maximum short-circuit current value that the circuit-breaker can break. It is verified according to a sequence of standardised tests. After this sequence, the circuit-breaker must not be dangerous. This characteristic is defined for a specific voltage rating Ue. |
Schneider | ||||||
| Current: Rated short-circuit making capacity | Icm | The rated short-circuit making capacity of a circuit-breaker is the value of short-circuit capacity assigned to that circuit-breaker by the manufacturer for the rated operational Making voltage at rated frequency and at a specified power factor for a,c., or time constant for d.c. It-is expressed as the maximum prospective peak current. For a c the rated short-circuit making capacity of a circuit-breaker shall be not less than its rated ultimate short-circuit breaking capacity, multiplied by the factor n of table 2 (see 4.3.5.3). For d c the rated short-circuit making capacity of a circuit-breaker shall be not less than its rated ultimate short-circuit breaking capacity. A rated short-circuit making capacity implies that the circuit-breaker shall be able to make the current corresponding to that rated capacity at the appropriate applied voltage related to the rated operational voltage. |
IEC 4.3.5.1 | ||||||
| Current: Rated short-circuit making capacity(*) (Icm) | Icm (peak kA) is the maximum value of the asymmetrical short-circuit current that the circuit-breaker can make and break. For a circuit-breaker, the stress to be managed is greatest on closing on a short-circuit. |
Schneider | |||||||
| Current: short-circuit release | an over-current release intended for protection against short circuits | IEC | IEV | ||||||
| CB: Current: making-current release | a release which permits a circuit-breaker to open, without any intentional time-delay, during a closing operation, if the making current exceeds a predetermined value, and which is rendered inoperative when the circuit-breaker is in the closed position | IEC | IEV | ||||||
| Cb: short-time delay short-circuit release | an over-current release intended to operate at the end of the short-time delay | IEC | IEV | ||||||
| Cascading:overcurrent trip selectivity | Means “coordination of the operating characteristics of two or more overcurrent protection devices so that, on occurrence of over currents within established limits, the device supposed to operate within these limits intervenes, whereas the others do not” 1 | ||||||||
| Cascading: Discrimination definition – Gary | Discrimation is the interaction between following (series) circuit protection devices where the one closest to the load will operate faster by design under all fault conditions. | Gary | |||||||
| Cascading: Discrimination: What is discrimination? |
Discrimination, also called selectivity, is the coordination of automatic protection devices in such a manner that a fault appearing at a given point in a network is cleared by the protection device installed immediately upstream of the fault, and by that device alone. |
Schneider | |||||||
| Cascading:Circuit-breaker coordination | Schneider | N The term coordination concerns the behaviour of two devices placed in series in electrical power distribution in the presence of a short-circuit. · Discrimination This consists of providing coordination between the operating characteristics of circuit-breakers placed in series so that should a downstream fault occur, only the circuit-breaker placed immediately upstream of the fault will trip. IEC 60947-2 defines a current value ls known as the discrimination limit such that: o if the fault current is less than this value ls, only the downstream circuit-breaker D2 trips, o if the fault current is greater than this value ls, both circuit-breakers D1 and D2 trip. Just as for cascading, discrimination must be verified by tests for critical points. Discrimination and cascading can only be guaranteed by the manufacturer who will record his tests in tables. |
|||||||
| Cascading:What is coordination | Coordination between following SCPD (short circuit protection device) / OLPD (overload protection device) - The use of a protective devices possessing a breaking capacity less than the prospective short-circuit current at its installation point is permitted as long as another device is installed upstream with at least the necessary breaking capacity. In this case, the characteristics of the two devices must be coordinated in such a way that the energy let through by the upstream device is not more than that which can be withstood by the downstream device and the cables protected by these devices without damage. |
Gary | |||||||
| Cascading: Coordination | Coordination (Selective). Localization of an over current condition to restrict outages to the circuit or equipment affected, accomplished by the choice of over current protective devices and their ratings or settings. | NEC | |||||||
| Coordination | Allows circuit breakers of lower breaking capacity then the PSCC tonbe installed. Based on the principle that breakers in series wil clear a larger fault and that energy let throuh from the upstream breaker will no damage the downstream device | Hager | |||||||
| Cascading:Discrimination NOT | In the event of a fault, both circuit breakers top and bottom operates |
Schneider | |||||||
Cascading: Discrimination (total selectivity) |
over-current discrimination where, in the presence of two over-current protective devices in series, the protective device on the load side effects the protection without causing the other protective device to operate |
||||||||
Cascading: Discrimination (total selectivity) |
total discrimination means “over current selectivity so that when there are two Over current protection devices in series, the protection device on the load side provides protection without tripping the other protection device” 2 ; | ||||||||
| Cascading:Discrimination total | Discrimination is said to be total if, for all fault current values, from overloads up to the non-resistive short-circuit current, circuit breaker D2 opens and D1 remains closed. |
Schneider | |||||||
Cascading:Discrimination (partial selectivity) |
over-current discrimination where, in the presence of two over-current protective devices in series, the protective device on the load side effects the protection up to a given level of overcurrent, without causing the other protective device to operate |
||||||||
Cascading: Discrimination (partial selectivity) |
partial discrimination means “overcurrent selectivity so that when there are two overcurrent protection devices in series, the protection device on the load side provides protection up to a given overcurrent limit without tripping the other device” 3 . This overcurrent threshold is called the “selectivity limit current I s ” 4 |
||||||||
| Cascading:Selectivity partial | Overcurrent selectivity where, in the presence of two protection devices against overcurrent in series, the load-side protection device carries out the protection up to a given level of overcurrent, without making the other device trip.” |
IEC 2.17.3 2.17.3 | IEC | ||||||
| Cascading: Discrimination partial | Discrimination is partial if the above condition is not respected up to the full shortcircuit current, but only to a lesser value termed the selectivity limit current (Is). |
Schneider | IEC | ||||||
| Cascading: Selectivity Current: selectivity limit current |
Is | the selectivity limit current is the current co-ordinate of the intersection between the total timecurrent characteristic of the protective device on the load side and the pre-arcing (for fuses), or tripping (for circuit-breakers) time-current characteristic of the other protective device The selectivity limit current (see figure Al) is a limiting value of current l below which, in the presence of two over-current protective devices in series, the protective device on the load side completes its breaking operation in time to prevent the other protective device from starting its operation (i.e. selectivity is ensured); . above which, in the presence of two over-current protective devices in series, the protective device on the load side may not complete its breaking operation in time to prevent |
IEC | IEV | |||||
| Cascading | Cascading or back-up protection This consists of installing an upstream circuit-breaker D1 to help a downstream circuit-breaker D2 to break short-circuit currents greater than its ultimate breaking capacity IcuD2. This value is marked IcuD2+D1. IEC 60947-2 recognises cascading between two circuit-breakers. For critical points, where tripping curves overlap, cascading must be verified by tests.(Schneider) |
||||||||
| Cascading | Also known as cascading: Energy liiting capacity of a feed cB | Hager | |||||||
| Current: Rated conditional short circuit current. | Icc | the short circuit current will initially flow and then be cleared by the protective device (this test is not given a time duration). Because of the complexities of ensuring appropriate selection is made, the second alternative rating, the Short Circuit Withstand (Icw) is often specified. | |||||||
| Current: conditional short-circuit current: (of a circuit or a switching device) | the prospective current that a circuit or a switching device, protected by a specified current limiting device, can satisfactorily withstand for the operating time of that current limiting device under specified conditions of use and behaviour | IEC | IEV | ||||||
| Current: Rated short-time withstand current | Icw | The rated short-time withstand current of a circuit-breaker is the value of short-time withstand current assigned to that circuit-breaker by the manufacturer under the test conditions specified In 8.3.6.2. For a.c., the value of this current is the r.m.s value of the a,c. component of the prospective short-circuit current, assumed constant during the short-time delay. The short-time delay associated with the rated short-time withstand current shall be at least 0,05 s, preferred values being as follows: 0,05 –0,1 –0,25–0,5–1 S The rated short-time withstand current shall be not less than the appropriate values shown in table 3 Table 3- Minimum values of rated short-time withstand current |
is.iec 60947-2.2003 – 4.3.5.4 | IEC | |||||
| Current:Take-over current |
Ib | subclause 2.5.25 of Part 1 is amplified as follows: For the purpose of this standard, 2.5.25 of Part 1 applies to two over-current protective devices in series for operating times 20,05 s. For operating times <0,05 s the two over-current devices in series are considered as an association, see annex A. NOTE The take-over current is the current co-ordinate of the intersection between the maximum break time current characteristics of two over-current protective devices in series.. |
is.iec40974-2.2003 – 2.17.6 | IEC | |||||
| Current: overcurrent protection | The term overcurrent protection includes both overload protection (see 6.7.2) and short-circuit protection (see 6.7.3). | IEC | |||||||
| Current: made and broken | Ic | Current made and broken | IEC60947-4-1 | IEC | |||||
| Current: Rated operational current | Ie | Rated operational current | IEC60947-4-1 | IEC | |||||
| Current: Rated rotor operational current | Ier | Rated rotor operational current | IEC60947-4-1 | IEC | |||||
| Current: Rated stator operational current | les | Rated stator operational current | IEC60947-4-1 | IEC | |||||
| Current: Inhibit current | lic | Inhibit current | IEC60947-4-1 | IEC | |||||
| Current: Conventional free air thermal current | Ith | Conventional free air thermal current | IEC60947-4-1 | IEC | |||||
| Current:Conventional enclosed thermal current | Ithe | Conventional enclosed thermal current | IEC60947-4-1 | IEC | |||||
| Current: Conventional rotor thermal current | Ithr | Conventional rotor thermal current | IEC60947-4-1 | IEC | |||||
| Current: Conventional stator thermal current | Iths | Conventional stator thermal current | IEC60947-4-1 | IEC | |||||
| Current: Rated uninterrupted current | lu | Rated uninterrupted current | IEC60947-4-1 | IEC | |||||
| Cascading principles | Influence of the electrical parameters of the installation (rated current and short- circuit current) If the analysis is restricted to the behaviour of the protection devices with tripping based on overcurrent releases, the strategy used to coordinate the protection devices mainly depends on the rated current (I n ) and short-circuit current (I k ) values in the part of installation concerned. Generally speaking, the following types of coordination can be classified: – current type selectivity; – time type selectivity; – zone selectivity; – energy selectivity; – back-up. Now let us examine these various solutions in detail. |
Schneider | |||||||
| selectivity limit current | Is | the selectivity limit current is the current co-ordinate of the intersection between the total timecurrent characteristic of the protective device on the load side and the pre-arcing (for fuses), or tripping (for circuit-breakers) time-current characteristic of the other protective device The selectivity limit current (see figure Al) is a limiting value of current ● below which, in the presence of two over-current protective devices in series, the protective device on the load side completes its breaking operation in time to prevent the other protective device from starting its operation (i.e. selectivity is ensured); . above which, in the presence of two over-current protective devices in series, the protective device on the load side may not complete its breaking operation in time to prevent the other protective device from starting its operation (i.e. selectivity is not ensured), 2.17.5 |
is.iec 60947-2.2003 – 2.17.4 | IEC | |||||
Cascading: Backup protection |
subclause 2.5,24 of Part 1 applies – | not mentioned in IEC | |||||||
| Cascading: back-up protection | means “coordination for protection against overcurrents of two protection devices in series, where the protection device generally (but not necessarily) situated on the supply side provides overcurrent protection with or without the aid of the other protection device and avoids excessive stress on the latter” 5 . The current value above which protection is ensured is called the “switching current I B ” 6 . |
Cacading tables abb | |||||||
| Accessible (as applied to equipment). | Admitting close approach; not guarded by locked doors, elevation, or other effective means. | NEC standard | NEC | ||||||
| Accessible (as applied to wiring methods). | Capable of being removed or exposed without damaging the building structure or finish or not permanently closed in by the structure or finish of the building. Accessible, Readily (Readily Accessible). Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, and so forth. |
NEC standard | NEC | ||||||
| Ampacity. | The current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Appliance. Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, food mixing, deep frying, and so forth. |
NEC standard | NEC | ||||||
| Approved | . Acceptable to the authority having jurisdiction. | NEC standard | NEC | ||||||
| Askarel. | A generic term for a group of nonflammable synthetic chlorinated hydrocarbons used as electrical insulating media. Askarels of various compositional types are used. Under arcing conditions, the gases produced, while consisting predominantly of noncombustible hydrogen chloride, can include varying amounts of combustible gases, depending on the askarel type. | NEC standard | NEC | ||||||
| Attachment Plug (Plug Cap) (Plug). | A device that, by insertion in a receptacle, establishes a connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle. | NEC standard | NEC | ||||||
| Authority Having Jurisdiction (AHJ). | An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure. The phrase “authority having jurisdiction,” or its acronym AHJ, is used in NFPA documents in a broad manner, since jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional department or individual such as a fire chief; fire marshal; chief of a fire prevention bureau, labor department, or health department; building official; electrical inspector; or others having statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or other insurance company representative may be the authority having jurisdiction. In many circumstances, the property owner or his or her designated agent assumes the role of the authority having jurisdiction; at government installations, the commanding officer or departmental official may be the authority having jurisdiction. | NEC standard | NEC | ||||||
| FPN: | NEC standard | NEC | |||||||
| Automatic. | Self-acting, operating by its own mechanism when actuated by some impersonal influence, as, for example, a change in current, pressure, temperature, or mechanical configuration. | NEC standard | NEC | ||||||
| Bathroom. | An area including a basin with one or more of the following: a toilet, a tub, or a shower. | NEC standard | NEC | ||||||
| Bonded (Bonding). | Connected to establish electrical continuity and conductivity. | NEC standard | NEC | ||||||
| A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected. | NEC standard | NEC | |||||||
| Bonding Jumper, Equipment. | The connection between two or more portions of the equipment grounding conductor. | NEC standard | NEC | ||||||
| Bonding Jumper, Main. | The connection between the grounded circuit conductor and the equipment grounding conductor at the service. | NEC standard | NEC | ||||||
| Branch Circuit. | The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s). | NEC standard | NEC | ||||||
| Branch Circuit, Appliance. | A branch circuit that supplies energy to one or more outlets to which appliances are to be connected and that has no permanently connected luminaires that are not a part of an appliance. | NEC standard | NEC | ||||||
| Branch Circuit, General-Purpose. | A branch circuit that supplies two or more receptacles or outlets for lighting and appliances. | NEC standard | NEC | ||||||
| Branch Circuit, Individual. | A branch circuit that supplies only one utilization equipment. | NEC standard | NEC | ||||||
| Branch Circuit, Multiwire. | A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system. | NEC standard | NEC | ||||||
| Branch-Circuit Overcurrent Device. | A device capable of providing protection for service, feeder, and branch circuits and equipment over the full range of overcurrents between its rated current and its interrupting rating. Branch-circuit overcurrent protective devices are provided with interrupting ratings appropriate for the intended use but no less than 5,000 amperes. | NEC standard | NEC | ||||||
| Building. | A structure that stands alone or that is cut off from adjoining structures by fire walls with all openings therein protected by approved fire doors. | NEC standard | NEC | ||||||
| Cabinet. | An enclosure that is designed for either surface mounting or flush mounting and is provided with a frame, mat, or trim in which a swinging door or doors are or can be hung. | NEC standard | NEC | ||||||
| Circuit Breaker. | A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating. The automatic opening means can be integral, direct acting with the circuit breaker, or remote from the circuit breaker. | NEC standard | NEC | ||||||
| Adjustable (as applied to circuit breakers). | A qualifying term indicating that the circuit breaker can be set to trip at various values of current, time, or both, within a predetermined range. | NEC standard | NEC | ||||||
| Instantaneous Trip (as applied to circuit breakers). | A qualifying term indicating that no delay is purposely introduced in the tripping action of the circuit breaker. | NEC standard | NEC | ||||||
| Inverse Time (as applied to circuit breakers). | A qualifying term indicating that there is purposely introduced a delay in the tripping action of the circuit breaker, which delay decreases as the magnitude of the current increases. | NEC standard | NEC | ||||||
| Nonadjustable (as applied to circuit breakers). | A qualifying term indicating that the circuit breaker does not have any adjustment to alter the value of current at which it will trip or the time required for its operation. | NEC standard | NEC | ||||||
| Setting (of circuit breakers). | The value of current, time, or both, at which an adjustable circuit breaker is set to trip. | NEC standard | NEC | ||||||
| Clothes Closet. | A non-habitable room or space intended primarily for storage of garments and apparel. | NEC standard | NEC | ||||||
| Communications Equipment. | The electronic equipment that performs the telecommunications operations for the transmission of audio, video, and data, and includes power equipment (e.g., dc converters, inverters, and batteries) and technical support equipment (e.g., computers). | NEC standard | NEC | ||||||
| Concealed. | Rendered inaccessible by the structure or finish of the building. Wires in concealed raceways are considered concealed, even though they may become accessible by withdrawing them. | NEC standard | NEC | ||||||
| Conductor, Bare. | A conductor having no covering or electrical insulation whatsoever. | NEC standard | NEC | ||||||
| Conductor, Covered. | A conductor encased within material of composition or thickness that is not recognized by this Code as electrical insulation. | NEC standard | NEC | ||||||
| Conductor, Insulated. | A conductor encased within material of composition and thickness that is recognized by this Code as electrical insulation. | NEC standard | NEC | ||||||
| Conduit Body. | A separate portion of a conduit or tubing system that provides access through a removable cover(s) to the interior of the system at a junction of two or more sections of the system or at a terminal point of the system. Boxes such as FS and FD or larger cast or sheet metal boxes are not classified as conduit bodies. |
NEC standard | NEC | ||||||
| Connector, Pressure (Solderless). | A device that establishes a connection between two or more conductors or between one or more conductors and a terminal by means of mechanical pressure and without the use of solder. | NEC standard | NEC | ||||||
| Continuous Load. | A load where the maximum current is expected to continue for 3 hours or more. | NEC standard | NEC | ||||||
| Controller. | A device or group of devices that serves to govern, in some predetermined manner, the electric power delivered to the apparatus to which it is connected. | NEC standard | NEC | ||||||
| Cooking Unit, Counter-Mounted. | A cooking appliance designed for mounting in or on a counter and consisting of one or more heating elements, internal wiring, and built-in or mountable controls. | NEC standard | NEC | ||||||
| Coordination (Selective). | Localization of an overcurrent condition to restrict outages to the circuit or equipment affected, accomplished by the choice of overcurrent protective devices and their ratings or settings. | NEC standard | NEC | ||||||
| Copper-Clad Aluminum Conductors. | Condseructors drawn from a copper-clad aluminum rod with the copper metallurgically bonded to an aluminum core. The copper forms a minimum of 10 percent of the cross-sectional area of a solid conductor or each strand of a stranded conductor. | NEC standard | NEC | ||||||
| Cutout Box. | An enclosure designed for surface mounting that has swinging doors or covers secured directly to and telescoping with the walls of the box proper. | NEC standard | NEC | ||||||
| Dead Front. | Without live parts exposed to a person on the operating side of the equipment. | NEC standard | NEC | ||||||
| Demand Factor. | The ratio of the maximum demand of a system, or part of a system, to the total connected load of a system or the part of the system under consideration. | NEC standard | NEC | ||||||
| Device. | A unit of an electrical system that carries or controls electric energy as its principal function. | NEC standard | NEC | ||||||
| Disconnecting Means. | A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply. | NEC standard | NEC | ||||||
| Dust-tight. | Constructed so that dust will not enter the enclosing case under specified test conditions. | NEC standard | NEC | ||||||
| Duty, Continuous. | Operation at a substantially constant load for an indefinitely long time. | NEC standard | NEC | ||||||
| Duty, Intermittent. | Operation for alternate intervals of (1) load and no load; or (2) load and rest; or (3) load, no load, and rest. | NEC standard | NEC | ||||||
| Duty, Periodic. | Intermittent operation in which the load conditions are regularly recurrent. | NEC standard | NEC | ||||||
| Duty, Short-Time | . Operation at a substantially constant load for a short and definite, specified time. | NEC standard | NEC | ||||||
| Duty, Varying. | Operation at loads, and for intervals of time, both of which may be subject to wide variation. | NEC standard | NEC | ||||||
| Dwelling, | One-Family. A building that consists solely of one dwelling unit. | NEC standard | NEC | ||||||
| Dwelling, Two-Family. | A building that consists solely of two dwelling units. | NEC standard | NEC | ||||||
| Dwelling, Multifamily. | A building that contains three or more dwelling units. | NEC standard | NEC | ||||||
| Dwelling Unit. | A single unit, providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation. | NEC standard | NEC | ||||||
| Electric Sign | . A fixed, stationary, or portable selfcontained, electrically illuminated utilization equipment with words or symbols designed to convey information or attract attention. | NEC standard | NEC | ||||||
| Electric Power Production and Distribution Network. | Power production, distribution, and utilization equipment and facilities, such as electric utility systems that deliver electric power to the connected loads, that are external to and not controlled by an interactive system. | NEC standard | NEC | ||||||
| Enclosed. | Surrounded by a case, housing, fence, or wall(s) that prevents persons from accidentally contacting energized parts. | NEC standard | NEC | ||||||
| Enclosure. | The case or housing of apparatus, or the fence or walls surrounding an installation to prevent personnel from accidentally contacting energized parts or to protect the equipment from physical damage. See Table 110.20 for examples of enclosure types. | NEC standard | NEC | ||||||
| Energized. | Electrically connected to, or is, a source of voltage. Equipment. A general term, including material, fittings, devices, appliances, luminaires, apparatus, machinery and the like used as a part of, or in connection with, an electrical installation. |
NEC standard | NEC | ||||||
| Explosion-proof Apparatus. | Apparatus enclosed in a case that is capable of withstanding an explosion of a specified gas or vapor that may occur within it and of preventing the ignition of a specified gas or vapor surrounding the enclosure by sparks, flashes, or explosion of the gas or vapor within, and that operates at such an external temperature that a surrounding flammable atmosphere will not be ignited thereby. For further information, see ANSI/UL 1203-1999, Explosion-Proof and Dust- | NEC standard | NEC | ||||||
| Ignition-Proof. | Electrical Equipment for Use in Hazardous (Classified) Locations. | NEC standard | NEC | ||||||
| Exposed (as applied to live parts). | Capable of being inadvertently touched or approached nearer than a safe distance by a person. It is applied to parts that are not suitably guarded, isolated, or insulated. | NEC standard | NEC | ||||||
| Exposed (as applied to wiring methods) | . On or attached to the surface or behind panels designed to allow access. | NEC standard | NEC | ||||||
| Externally Operable. | Capable of being operated without exposing the operator to contact with live parts. | NEC standard | NEC | ||||||
| Feeder. | All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device. | NEC standard | NEC | ||||||
| Festoon Lighting. | A string of outdoor lights that is suspended between two points. | NEC standard | NEC | ||||||
| Fitting. | An accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function. | NEC standard | NEC | ||||||
| Garage. | A building or portion of a building in which one or more self-propelled vehicles can be kept for use, sale, storage, rental, repair, exhibition, or demonstration purposes. | NEC standard | NEC | ||||||
| Ground | . The earth. | NEC standard | NEC | ||||||
| Grounded. (Grounding) | . Connected (connecting) to ground or to a conductive body that extends the ground connection. | NEC standard | NEC | ||||||
| Grounded, Solidly | . Connected to ground without inserting any resistor or impedance device. | NEC standard | NEC | ||||||
| Grounded Conductor. | A system or circuit conductor that is intentionally grounded. | NEC standard | NEC | ||||||
| Ground-Fault Circuit Interrupter (GFCI). | A device intended for the protection of personnel that functions to deenergize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a Class A device. FPN: Class A ground-fault circuit interrupters trip when the current to ground is 6 mA or higher and do not trip when the current to ground is less than 4 mA. For further information, see UL 943, Standard for Ground-Fault Circuit Interrupters. | NEC standard | NEC | ||||||
| Ground-Fault Protection of Equipment | . A system intended to provide protection of equipment from damaging line-to-ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit. This protection is provided at current levels less than those required to protect conductors from damage through the operation of a supply circuit overcurrent device. | NEC standard | NEC | ||||||
| Grounding Conductor. | A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes. | NEC standard | NEC | ||||||
| Grounding Conductor, Equipment (EGC) | . The conductive path installed to connect normally non–currentcarrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode, or both. FPN No1: It is recognized that the equipment grounding conductor also performs bonding.FPN No2: See 250.118 for a list of acceptable equipment grounding conductors. | NEC standard | NEC | NEC | |||||
| Grounding Electrode. | A conducting object through which a direct connection to earth is established. | NEC standard | NEC | ||||||
| Grounding Electrode Conductor | . A conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system. | NEC standard | NEC | NEC | |||||
| Guarded. | Covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casings, barriers, rails, screens, mats, or platforms to remove the likelihood of approach or contact by persons or objects to a point of danger. | NEC standard | NEC | ||||||
| Guest Room. | An accommodation combining living, sleeping, sanitary, and storage facilities within a compartment. | NEC standard | NEC | ||||||
| Guest Suite. | An accommodation with two or more contiguous rooms comprising a compartment, with or without doors between such rooms, that provides living, sleeping, sanitary, and storage facilities. | NEC standard | NEC | ||||||
| Handhole Enclosure. | An enclosure for use in underground systems, provided with an open or closed bottom, and sized to allow personnel to reach into, but not enter, for the purpose of installing, operating, or maintaining equipment or wiring or both. | NEC standard | NEC | ||||||
| Hoistway | . Any shaftway, hatchway, well hole, or other vertical opening or space in which an elevator or dumbwaiter is designed to operate. | NEC standard | NEC | ||||||
| Identified (as applied to equipment). | Recognizable as suitable for the specific purpose, function, use, environment, application, and so forth, where described in a particular Code requirement.. Some examples of ways to determine suitability of equipment for a specific purpose, environment, or application include investigations by a qualified testing laboratory (listing and labeling), an inspection agency, or other organizations concerned with product evaluation. | NEC standard | NEC | ||||||
| In Sight From (Within Sight From, Within Sight). | Where this Code specifies that one equipment shall be “in sight from,” “within sight from,” or “within sight of,” and so forth, another equipment, the specified equipment is to be visible and not more than 15 m (50 ft) distant from the other. | NEC standard | NEC | ||||||
| Interactive System | . An electric power production system that is operating in parallel with and capable of delivering energy to an electric primary source supply system. | NEC standard | NEC | ||||||
| Interrupting Rating. | The highest current at rated voltage that a device is intended to interrupt under standard test conditions. Equipment intended to interrupt current at other than fault levels may have its interrupting rating implied in other ratings, such as horsepower or locked rotor current. | NEC standard | NEC | ||||||
| Intersystem Bonding Termination. | A device that provides a means for connecting communications system(s) grounding conductor(s) and bonding conductor(s) at the service equipment or at the disconnecting means for buildings or structures supplied by a feeder or branch circuit. | NEC standard | NEC | ||||||
| Isolated (as applied to location). | Not readily accessible to persons unless special means for access are used. | NEC standard | NEC | ||||||
| Kitchen. | An area with a sink and permanent facilities for food preparation and cooking. | NEC standard | NEC | ||||||
| Labeled. | Equipment or materials to which has been attached a label, symbol, or other identifying mark of an organization that is acceptable to the authority having jurisdiction and concerned with product evaluation, that maintains periodic inspection of production of labeled equipment or materials, and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner. | NEC standard | NEC | ||||||
| Lighting Outlet. | An outlet intended for the direct connection of a lampholder or luminaire. | NEC standard | NEC | ||||||
| Listed. | Equipment, materials, or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that either the equipment, material, or service meets appropriate designated standards or has been tested and found suitable for a specified purpose. | NEC standard | NEC | ||||||
| FPN: | The means for identifying listed equipment may vary for each organization concerned with product evaluation, some of which do not recognize equipment as listed unless it is also labeled. Use of the system employed by the listing organization allows the authority having jurisdiction to identify a listed product. | NEC standard | NEC | ||||||
| Live Parts. | Energized conductive components. | NEC standard | NEC | ||||||
| Location, Damp. | Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold storage warehouses. | NEC standard | NEC | ||||||
| Location, Dry. | A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction. | NEC standard | NEC | ||||||
| Location, Wet. | Installations underground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather. | NEC standard | NEC | ||||||
| Luminaire. | A complete lighting unit consisting of a light source such as a lamp or lamps, together with the parts designed to position the light source and connect it to the power supply. It may also include parts to protect the light source or the ballast or to distribute the light. A lampholder itself is not a luminaire. | NEC standard | NEC | ||||||
| Metal-Enclosed Power Switchgear. | A switchgear assembly completely enclosed on all sides and top with sheet metal (except for ventilating openings and inspection windows) and containing primary power circuit switching, interrupting devices, or both, with buses and connections. The assembly may include control and auxiliary devices. Access to the interior of the enclosure is provided by doors, removable covers, or both. Metal-enclosed power switch gear is available in non-arc-resistant or arc-resistant constructions. | NEC standard | NEC | ||||||
| Motor Control Center. | An assembly of one or more enclosed sections having a common power bus and principally containing motor control units. | NEC standard | NEC | ||||||
| Multioutlet Assembly. | A type of surface, flush, or freestanding raceway designed to hold conductors and receptacles, assembled in the field or at the factory. | NEC standard | NEC | ||||||
| Neutral Conductor. | The conductor connected to the neutral point of a system that is intended to carry current under normal conditions. | NEC standard | NEC | ||||||
| Neutral Point. | The common point on a wye-connection in a polyphase system or midpoint on a single-phase, 3-wire system, or midpoint of a single-phase portion of a 3-phase delta system, or a midpoint of a 3-wire, direct-current system.. At the neutral point of the system, the vectorial sum of the nominal voltages from all other phases within the system that utilize the neutral, with respect to the neutral point, is zero potential. | NEC standard | NEC | ||||||
| Nonautomatic. | Action requiring personal intervention for its control. As applied to an electric controller, nonautomatic control does not necessarily imply a manual controller, but only that personal intervention is necessary. | NEC standard | NEC | ||||||
| Nonlinear Load. | A load where the wave shape of the steady-state current does not follow the wave shape of the applied voltage. FPN: Electronic equipment, electronic/electric-discharge lighting, adjustable-speed drive systems, and similar equipment may be nonlinear loads. Outlet. A point on the wiring system at which current is taken to supply utilization equipment. | NEC standard | NEC | ||||||
| Outline Lighting. | An arrangement of incandescent lamps, electric-discharge lighting, or other electrically powered light sources to outline or call attention to certain features such as the shape of a building or the decoration of a window. | NEC standard | NEC | ||||||
| Overcurrent | . Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload, short circuit, or ground fault. FPN: Where service equipment is located outside the building walls, there may be no service-entrance conductors or they may be entirely outside the building. | NEC standard | NEC | ||||||
| Service Equipment. | The necessary equipment, usually consisting of a circuit breaker(s) or switch(es) and fuse(s) and their accessories, connected to the load end of service conductors to a building or other structure, or an otherwise designated area, and intended to constitute the main control and cutoff of the supply. | NEC standard | NEC | ||||||
| Service Lateral. | The underground service conductors between the street main, including any risers at a pole or other structure or from transformers, and the first point of connection to the service-entrance conductors in a terminal box or meter or other enclosure, inside or outside the building wall. Where there is no terminal box, meter, or other enclosure, the point of connection is considered to be the point of entrance of the service conductors into the building. | NEC standard | NEC | ||||||
| Service Point. | The point of connection between the facilities of the serving utility and the premises wiring. | NEC standard | NEC | ||||||
| Short-Circuit Current Rating. | The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria. | NEC standard | NEC | ||||||
| Show Window. | Any window used or designed to be used for the display of goods or advertising material, whether it is fully or partly enclosed or entirely open at the rear and whether or not it has a platform raised higher than the street floor level. | NEC standard | NEC | ||||||
| Signaling Circuit. | Any electrical circuit that energizes signaling equipment. | NEC standard | NEC | ||||||
| Solar Photovoltaic System. | The total components and subsystems that, in combination, convert solar energy into electric energy suitable for connection to a utilization load. | NEC standard | NEC | ||||||
| Special Permission. | The written consent of the authority having jurisdiction. | NEC standard | NEC | ||||||
| Structure. | That which is built or constructed. | NEC standard | NEC | ||||||
| Supplementary Overcurrent Protective Device. | A device intended to provide limited overcurrent protection for specific applications and utilization equipment such as luminaires and appliances. This limited protection is in addition to the protection provided in the required branch circuit by the branch circuit overcurrent protective device. | NEC standard | NEC | ||||||
| Surge Arrester. | A protective device for limiting surge voltages by discharging or bypassing surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions. | NEC standard | NEC | ||||||
| Surge-Protective Device (SPD). | A protective device for limiting transient voltages by diverting or limiting surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions and is designated as follows: Type 1: Permanently connected SPDs intended for installation between the secondary of the service transformer and the line side of the service disconnect overcurrent device. Type 2: Permanently connected SPDs intended for installation on the load side of the service disconnect overcurrent device, including SPDs located at the branch panel. Type 3: Point of utilization SPDs. Type 4: Component SPDs, including discrete components, as well as assemblies. FPN: For further information on Type 1, Type 2, Type 3, and Type 4 SPDs, see UL 1449, Standard for Surge Protective Devices. |
NEC standard | NEC | ||||||
| Switch, Bypass Isolation. | A manually operated device used in conjunction with a transfer switch to provide a means of directly connecting load conductors to a power source and of disconnecting the transfer switch. | NEC standard | NEC | ||||||
| Switch, General-Use. | A switch intended for use in general distribution and branch circuits. It is rated in amperes, and it is capable of interrupting its rated current at its rated voltage. | NEC standard | NEC | ||||||
| Switch, General-Use Snap. | A form of general-use switch constructed so that it can be installed in device boxes or on box covers, or otherwise used in conjunction with wiring systems recognized by this Code. | NEC standard | NEC | ||||||
| Switch, Isolating | . A switch intended for isolating an electrical circuit from the source of power. It has no interrupting rating, and it is intended to be operated only after the circuit has been opened by some other means. | NEC standard | NEC | ||||||
| Switch, Motor-Circuit. | A switch rated in horsepower that is capable of interrupting the maximum operating overload current of a motor of the same horsepower rating as the switch at the rated voltage. | NEC standard | NEC | ||||||
| Switch, Transfer. | An automatic or nonautomatic device for transferring one or more load conductor connections from one power source to another. | NEC standard | NEC | ||||||
| Switchboard. | A large single panel, frame, or assembly of panels on which are mounted on the face, back, or both, switches, overcurrent and other protective devices, buses, and usually instruments. Switchboards are generally accessible from the rear as well as from the front and are not intended to be installed in cabinets. | NEC standard | NEC | ||||||
| Thermally Protected (as applied to motors). | The words Thermally Protected appearing on the nameplate of a motor or motor-compressor indicate that the motor is provided with a thermal protector. | NEC standard | NEC | ||||||
| Thermal Protector (as applied to motors). | A protective device for assembly as an integral part of a motor or motorcompressor that, when properly applied, protects the motor against dangerous overheating due to overload and failure to start. FPN: The thermal protector may consist of one or more sensing elements integral with the motor or motorcompressor and an external control device. Ungrounded. Not connected to ground or to a conductive body that extends the ground connection. | NEC standard | NEC | ||||||
| Utility-Interactive Inverter | . An inverter intended for use in parallel with an electric utility to supply common loads that may deliver power to the utility. | NEC standard | NEC | ||||||
| Utilization Equipment. | Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes. | NEC standard | NEC | ||||||
| Ventilated. | Provided with a means to permit circulation of air sufficient to remove an excess of heat, fumes, or vapors. | NEC standard | NEC | ||||||
| Volatile Flammable Liquid. | A flammable liquid having a flash point below 38°C (100°F), or a flammable liquid whose temperature is above its flash point, or a Class II combustible liquid that has a vapor pressure not exceeding 276 kPa (40 psia) at 38°C (100°F) and whose temperature is above its flash point. | NEC standard | NEC | ||||||
| Voltage (of a circuit) | . The greatest root-mean-square (rms) (effective) difference of potential between any two conductors of the circuit concerned. Some systems, such as 3-phase 4-wire, single-phase 3-wire, and 3-wire direct current, may have various circuits of various voltages. | NEC standard | NEC | ||||||
| Voltage, Nominal. | A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment. FPN: See ANSI C84.1-2006, Voltage Ratings for Electric Power Systems and Equipment (60 Hz). | NEC standard | NEC | ||||||
| Voltage to Ground. | For grounded circuits, the voltage between the given conductor and that point or conductor of the circuit that is grounded; for ungrounded circuits, the greatest voltage between the given conductor and any other conductor of the circuit. | NEC standard | NEC | ||||||
| Watertight. | Constructed so that moisture will not enter the enclosure under specified test conditions. | NEC standard | NEC | ||||||
| Weatherproof | . Constructed or protected so that exposure to the weather will not interfere with successful operation. FPN: Rainproof, raintight, or watertight equipment can fulfill the requirements for weatherproof where varying weather conditions other than wetness, such as snow, ice, dust, or temperature extremes, are not a factor. | NEC standard | NEC | ||||||
| NEC standard | NEC | ||||||||
| Fuse: Electronically Actuated Fuse. | An overcurrent protective device that generally consists of a control module that provides current sensing, electronically derived time–current characteristics, energy to initiate tripping, and an interrupting module that interrupts current when an overcurrent occurs. Electronically actuated fuses may or may not operate in a current-limiting fashion, depending on the type of control selected. | NEC standard | NEC | ||||||
| Fuse. | NEC standard | NEC | |||||||
| Fuse: N.American: The replacable part - | An overcurrent protective device with a circuitopening fusible part that is heated and severed by the passage of overcurrent through it. FPN: A fuse comprises all the parts that form a unit capable of performing the prescribed functions. It may or may not be the complete device necessary to connect it into an electrical circuit. |
UL/NEC | NEC | ||||||
| Fuse link: An metal bridge in place of the fuse | |||||||||
| Fuse link – IEC – The replacable element | |||||||||
| Fuse; IEC- The complete asenbly – replacable element and holder (quite silly isnt it!) | |||||||||
| Fuse holder – IEC – the housing to the replacable part | |||||||||
| Controlled Vented Power Fuse. | A fuse with provision for controlling discharge circuit interruption such that no solid material may be exhausted into the surrounding atmosphere. FPN: The fuse is designed so that discharged gases will not ignite or damage insulation in the path of the discharge or propagate a flashover to or between grounded members or conduction members in the path of the discharge where the distance between the vent and such insulation or conduction members conforms to manufacturer’s recommendations. | NEC standard | NEC | ||||||
| Expulsion Fuse Unit (Expulsion Fuse). | A vented fuse unit in which the expulsion effect of gases produced by the arc and lining of the fuseholder, either alone or aided by a spring, extinguishes the arc. | NEC standard | NEC | ||||||
| Nonvented Power Fuse | . A fuse without intentional provision for the escape of arc gases, liquids, or solid particles to the atmosphere during circuit interruption. | NEC standard | NEC | ||||||
| Power Fuse Unit. | A vented, nonvented, or controlled vented fuse unit in which the arc is extinguished by being drawn through solid material, granular material, or liquid, either alone or aided by a spring. | NEC standard | NEC | ||||||
| Vented Power Fuse. | A fuse with provision for the escape of arc gases, liquids, or solid particles to the surrounding atmosphere during circuit interruption. | NEC standard | NEC | ||||||
| Multiple Fuse. | An assembly of two or more single-pole fuses. | NEC standard | NEC | ||||||
| Switching Device | . A device designed to close, open, or both, one or more electrical circuits. | NEC standard | NEC | ||||||
| Circuit Breaker. | A switching device capable of making, carrying, and interrupting currents under normal circuit conditions, and also of making, carrying for a specified time, and interrupting currents under specified abnormal circuit conditions, such as those of short circuit. | NEC standard | NEC | ||||||
| Cutout. | An assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link) or may act as the disconnecting blade by the inclusion of a nonfusible member. | NEC standard | NEC | ||||||
| Disconnecting Means. | A device, group of devices, or other means whereby the conductors of a circuit can be disconnected from their source of supply. | NEC standard | NEC | ||||||
| Switch (Disconnector, Isolator) | . A mechanical switching device used for isolating a circuit or equipment from a source of power. | NEC standard | NEC | ||||||
| Interrupter Switch. | A switch capable of making, carrying, and interrupting specified currents. | NEC standard | NEC | ||||||
| Oil Cutout (Oil-Filled Cutout). | A cutout in which all or part of the fuse support and its fuse link or disconnecting blade is mounted in oil with complete immersion of the contacts and the fusible portion of the conducting element (fuse link) so that arc interruption by severing of the fuse link or by opening of the contacts will occur under oil. | NEC standard | NEC | ||||||
| Oil Switch. | A switch having contacts that operate under oil (or askarel or other suitable liquid). | NEC standard | NEC | ||||||
| Regulator Bypass Switch. | A specific device or combination of devices designed to bypass a regulator. | NEC standard | NEC | ||||||
| Molded Case Circuit Breaker | mccb | Molded Case Circuit Breaker | NEC standard | NEC | |||||
| Miniature Circuit Breaker | mcb | Miniature Circuit Breaker | NEC standard | NEC | |||||
| Air Circuit Breaker | ACB | Air Circuit Breaker | NEC | ||||||
| Current: Rated conditional short circuit current. | Icc | This is the rating that is associated with a SCPD; the short circuit current will initially flow and then be cleared by the protective device (this test is not given a time duration). Because of the complexities of ensuring appropriate selection is made, the second alternative rating, the Short Circuit Withstand (Icw) is often specified. | NEC | ||||||
| Current: Rated Short Time Withstand Current. | Icw | This is the rating of current that the assembly can withstand for a set period of time without the aid of a SCPD. The rating is made up of 2 parts: the RMS rating in kA and the duration. There is no international standard for the timing, however times of 0.5, 1 and 3 seconds are commonly used. Icw includes the Rated Peak Withstand Current (Ipk), which is a surge of current that occurs on one phase of the system in the first full cycle, as well as the changes of electro-magnetic forces that occur through the number of cycles seen during the test. The number of cycles is dependent on the frequency of the supply and duration of the test. For example, if the test supply is 50Hz and the duration is 3 seconds, there will have been 150 cycles. | NEC | ||||||
| Current: Rated short time withstand current(*) (Icw) | Defined for B category circuit-breakers Icw (kA rms) is the maximum short-circuit current that the circuit-breaker can withstand for a short period of time (0.05 to 1 s) without its properties being affected. This performance is verified during the standardised test sequence. |
Schneider | Schneider | ||||||
| Current: Rated conditional short circuit current. | Icc | This is the rating that is associated with a SCPD; the short circuit current will initially flow and then be cleared by the protective device (this test is not given a time duration). Because of the complexities of ensuring appropriate selection is made, the second alternative rating, the Short Circuit Withstand (Icw) is often specified. | IEC | IEC | |||||
| Current: Rated conditional short circuit current. | The value of current component of a prospective current , which a switch without integral short-crcuit protection, but protected by a suitable SCPD in series, can withstand for the operating time of the current under specified conditions. | schneider FAQ | IEC | ||||||
| Current: Rated Short Time Withstand Current. | Icw | This is the rating of current that the assembly can withstand for a set period of time without the aid of a SCPD. The rating is made up of 2 parts: the RMS rating in kA and the duration. There is no international standard for the timing, however times of 0.5, 1 and 3 seconds are commonly used. Icw includes the Rated Peak Withstand Current (Ipk), which is a surge of current that occurs on one phase of the system in the first full cycle, as well as the changes of electro-magnetic forces that occur through the number of cycles seen during the test. The number of cycles is dependent on the frequency of the supply and duration of the test. For example, if the test supply is 50Hz and the duration is 3 seconds, there will have been 150 cycles. | IEC | ||||||
| Current: Short Circuit interrupting current | Iint | Breaking capacity Max short circuit current at rated voltage that an over current protective device can safely interrupt and clear (fuses / CB) | Rockwell | NEC | |||||
| Current : Short circuit current rating | SCCR | Max. available shirt circuiit current and electrical compnonent can sustain without the osccurance iof excessive damage when protected with an over current protective device. | Rockwell | NEC | |||||
| Current: Short circuit prospective fault | Icp | rockwell | IEC | ||||||
| Current: Conventional Free Air Thermal Current Ith | Ith | Current that the contactor can withstand in free air for a duty time of 8 hours without the temperature rise of its various parts exceeding the maximum values given by the standard. | |||||||
| Operating Cycle or Cycle | Includes one making operation and one breaking operation. | ||||||||
| Cycle Time | This is the sum of the current flow time and the no-current time for given cycle. | ||||||||
| Electrical Durability | Number of on-load operating cycles that the contactor is able to carry out. It depends on the utilization category. | ||||||||
| Mechanical Durability | Number of no-current operating cycles that a contactor is able to carry out. | ||||||||
| Assessed Failure Rate | Defined according to IEC 60947-5-4. This rate is given in standard industrial environments for the contactor relays and for the built-in auxiliary contact of contactors. | ||||||||
| Load Factor | Ratio of the on-load operating time to the total cycle time x 100. | ||||||||
| Switching Frequency | Number of switching cycles per hour. | ||||||||
| Plugging | Stopping or fast reversal in rotation direction of a motor by two supply leads being interchanged while the motor is running. | ||||||||
| Inching | Energization of a motor's circuit repeatedly or for short periods with the aim of obtaining small movements of the driven mechanism. | ||||||||
| Coil Operating Limits | Expressed in multiples of the nominal control circuit voltage Uc for the upper and lower limits. | ||||||||
| Mounting Position | Comply with the manufacturer's instructions. Restrictions are to be taken into account for certain mounting positions. | ||||||||
| Current: Rated Breaking or Making Capacity | Irms | Root mean square (r.m.s.) value of the current that the contactor is able to break or make at a given voltage according to the conditions specified by standards and for a given utilization category. | |||||||
| Intermittent Duty | Duty during which the contactor is successively closed or open for periods which are too short to enable the contactor to achieve thermal balance. | ||||||||
| Ambient Temperature | Air temperature close to the contactor. | ||||||||
| Time | RC | – Time constant:: Ratio of the inductance to the resistance (L/R = mH/= ms). | |||||||
| Current: – Short-time withstand current: | Icw | Current that the contactor is able to withstand in closed position for a short time interval and in specified conditions. | |||||||
| Closing time:(cb) | t | Time interval between the beginning of the closing operation and the instant the contacts touch on all the poles. | |||||||
| Opening time: (cb) | t | Time interval between the specified starting instant of the opening operation and the instant the contacts separate on all the poles. | |||||||
| Voltage: Rated Control Voltage Uc | Uc | Control voltage value for which the control circuit is sized. | |||||||
| Voltage: Rated Operational Voltage Ue | Ue | Voltage to which the contactor's utilization characteristics refer. In three-phase it is the phase-to-phase voltage. | |||||||
| Voltage: Rated Insulation Voltage Ui | Ui | Reference voltage for dielectric tests and creepage distances. | |||||||
| Rated Impulse Withstand Voltage Uimp | Uimp | Peak value of an impulse voltage, having a specified form and polarity, which does not cause breakdown in specific test conditions. | |||||||
| Shock Withstand | Requirement for vehicles, crane drives, installations on board ships and plug-in equipment. For the acceptable "g" values, the contacts must not change position and the thermal overload relays must not trip. | ||||||||
| Resistance to Vibrations | Requirements for vehicles, boats and other means of transport. For the specified vibration amplitude and frequency values the device must remain able to operate. | ||||||||
| ANSI code: 51, AC time overcurrent relay | NEC | ||||||||
| NEC | |||||||||
| NEC | |||||||||
| ANSI code: 50, instantaneous overcurrent relay); | NEC | ||||||||
| ANSI code: 51 N, AC time earth fault overcurrent relay | NEC | ||||||||
| high breaking capacity (fuse) | HBC | ||||||||
| high rupturing capacity (fuse) | HRC | ||||||||
| Acronym | Description | ||||||||
| arc-fault circuit interrupter | AFCI | ||||||||
| cross-sectional area | c.s.a | ||||||||
| cable grouping correction factor | Cg | ||||||||
| thermal insulation correction factor | Ci | ||||||||
| combined neutral and earth | CNE | ||||||||
| power factor (sinusoidal systems) | cos 0 | ||||||||
| circuit protective conductor | CPC | ||||||||
| correction factor for the conductor operating temperature | Ct | ||||||||
| overall cable diameter | De | ||||||||
| Electrical Contractors Association | ECA | ||||||||
| earthed equipotential bonding & automatic disconnection | EEBAD | ||||||||
| extra-low voltage | ELV | Extra low voltage circuit | |||||||
| Electromagnetic compatibility | EMC | Electromagnetic compatibility | |||||||
| Electromagnetic interference | EMI | Electromagnetic interference | |||||||
| Functionally earthed extra low voltage | FELV | Functionally grounded (earthed) extra low voltage circuit, which may or may not be separated from higher voltage circuits | |||||||
| Groundfault circuit Groundfault circuit | GFCI | USA | |||||||
| Current: Tabulated current-carrying capacity | It | The calculated current after all correction factors applied e.g. in cable sizing after considering distance and/or temperature etc.current | UK | ||||||
| Isolated from earth type of supply system: (Isolated Terra) gs | IT | Ungrounded (isolated) electrical supply system with or without a distributed neutral. Equipment is grounded (earthed) | |||||||
| Information technology equipment | ITE | ||||||||
| Protective earthed conductor | PE | Protective earthed conductor (equipment grounding conductor) | |||||||
| Protectively grounded (earthed) extra low voltage , | PELV | Circuit below 50Vac or 120Vdc which is separated from higher voltage circuits (AN EARTHED SYSTEM) | SANS, | ||||||
| Protective Earth and Neutral (combined) conductor | PEN | Protective earthed neutral conductor (also serves as an equipment grounding conductor) | |||||||
| protective multiple earthing | PME | ||||||||
| Residual current device (senses and responds to interrupt the circuit on ground faults) | RCD | ||||||||
| Safety Extra low voltage | SELV | Circuit below 50Vac or 120Vdc which is isolated from higher voltage parts and from grounded(earthed) parts (AN UNEARTHED SYSTEM) | SANS, | ||||||
| Neutral grounded (earthed) electrical supply system | TN | A neutral grounded (earthed) electrical supply system | |||||||
| Neutral grounded (earthed) electrical supply system where the neutral serves as the protective conductor, i.e. PEN conductor (TN-C) | TNC | A neutral grounded (earthed) electrical supply system where the neutral serves as the protective conductor, i.e. PEN conductor | |||||||
| Neutral grounded (earthed) electrical supply system where, in part of the installation, a PEN conductor is used and in other parts a separate PE conductor is used (TN-C-S) | TNCS | A neutral grounded (earthed) electrical supply system where, in part of the installation, a PEN conductor is used and in other parts a separate PE conductor is used | |||||||
| Neutral grounded (earthed) electrical supply system with separate neutral and protective earthed (PE) conductors (TN-S) | TNS | A neutral grounded (earthed) electrical supply system with separate neutral and protective earthed (PE) conductors | |||||||
| Neutral grounded (earthed) electrical supply system where the source neutral and the electricale quipment are grounded (earthed) separately (earth serves as the return path for leakage and fault currents | TT | A neutral grounded (earthed) electrical supply system where the source neutral and the electricale quipment are grounded (earthed) separately (earth serves as the return path for leakage and faultcurrents | |||||||
| Current: Design current | The calculated current based on Kw (considering the PF) | UK | |||||||
| Grounding Conductor | A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes. | NEC | |||||||
| Grounding Conductor, Equipment (EGC). | EGC | The conductive path installed to connect normally non–current carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode, or both. FPN No. 1: It is recognized that the equipment grounding conductor also performs. FPN No. 2: See 250.118 for a list of acceptable equipment grounding conductors. | NEC | ||||||
| bonding. | NEC | ||||||||
| NEC | |||||||||
| Grounding Electrode. | A conducting object through which a direct connection to earth is established. | NEC | |||||||
| Grounding Electrode Conductor. | A conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system. | NEC | |||||||
Switch: Load-break switch |
The load break switch is a mechanical switching device capable of making, carrying and breaking currents under normal circuit conditions which may include specified operating overload conditions and also carrying for a specified time currents under specified abnormal circuit conditions such as those of shortcircuit. A load switch may be capable of making but not breaking, short-circuit currents (IEC 947-1). It is capable of carrying (high short-time withstand capability) but not breaking the short-circuit currents. |
IEC | |||||||
| Main switch:- | |||||||||
| Emergency OFF-switch | |||||||||
| ELCB | earth leakage circuit breaker | IEC | |||||||
| (Fused Connection Unit incorporating a Residual Current Device) | FCURCD | A fused connection unit for fixed installations incorporating an integral sensing circuit that will automatically cause the switching contacts in the main circuit to open at a predetermined value of residual current | IEC | ||||||
| (Fused Connection Unit incorporating a Residual Current Device) | FCURCD | A fused connection unit for fixed installations incorporating an integral sensing circuit that will automatically cause the switching contacts in the main circuit to open at a predetermined value of residual current |
IEC | ||||||
| Portable Residual Current Device | PRCD | - A device comprising a plug, a residual current device and one or more socket-outlets (or a provision for connection). It may incorporate over-current protection |
IEC | ||||||
| Portable Residual Current Device - | PRCD | A device comprising a plug, a residual current device and one or more socket-outlets (or a provision for connection). It may incorporate over-current protection |
IEC | ||||||
| (Residual Current Operated Circuit-Breaker with Integral Overcurrent Protection) | RCBO | A mechanical switching device designed to make, carry and break currents under normal service conditions and to cause the opening of the contacts when the residual current attains a given value under specified conditions. In addition it is designed to give protection against overloads and/or short-circuits and can be used independently of any other overcurrent protective device within its rated short-circuit capacity. |
IEC | ||||||
| (Residual Current Operated Circuit-Breaker with Integral Overcurrent Protection) | RCBO | A mechanical switching device designed to make, carry and break currents under normal service conditions and to cause the opening of the contacts when the residual current attains a given value under specified conditions. In addition it is designed to give protection against overloads and/or short-circuits and can be used independently of any other overcurrent protective device within its rated short-circuit capacity. |
IEC | ||||||
| Residual current Ciuit Breaker | RCCB | A mechanical switching device designed to make, carry and break currents under normal service conditions and to cause the opening of the contacts when the residual current attains a given value under specified conditions. It is not designed to give protection against overloads and/or short-circuits and must always be used in conjunction with an overcurrent protective device such as a fuse or circuit-breaker. |
IEC | ||||||
| (Residual Current Operated Circuit-Breaker without Integral Overcurrent Protection) | RCCB | (Residual Current Operated Circuit-Breaker without Integral Overcurrent Protection) A mechanical switching device designed to make, carry and break currents under normal service conditions and to cause the opening of the contacts when the residual current attains a given value under specified conditions. It is not designed to give protection against overloads and/or short-circuits and must always be used in conjunction with an overcurrent protective device such as a fuse or circuit-breaker. |
IEC | ||||||
| (Socket-Outlet incorporating a Residual Current Device) | SRCD | A socket-outlet for fixed installations incorporating an integral sensing circuit that will automatically cause the switching contacts in the main circuit to open at a predetermined value of residual current. |
IEC | ||||||
| (Socket-Outlet incorporating a Residual Current Device) | SRCD | A socket-outlet for fixed installations incorporating an integral sensing circuit that will automatically cause the switching contacts in the main circuit to open at a predetermined value of residual current. |
IEC | ||||||
| A | Accelerating | ||||||||
| AM | Ammeter | ||||||||
| American Wire GaugeAmerican Wire Gauge | AWG | ||||||||
| B | Braking | ||||||||
| bayonet cap | BC | ||||||||
| C or CAP | Capacitor, capacitance | ||||||||
| ambient temperature correction factor | Ca | ||||||||
| Circuit-breaker | CB | Circuit-breaker | |||||||
| cosphi | phase angle | ||||||||
| CR | Control relay | ||||||||
| CT | Current transformer | ||||||||
| D | Diode | ||||||||
| DB | Dynamic braking | ||||||||
| DM | Demand meter | ||||||||
| DS or DISC | Disconnect switch | ||||||||
| electro-motive force | e.m.f. | ||||||||
| electro-magnetic compatibility | EMC | ||||||||
| Electromagnetic Interference (EMI) : | EMI | Unwanted electrical energy that has the possibility of producing undesirable effects in the control, its circuits and system. | |||||||
| Electromagnetic Interference(EMI) | EMI | Electromagnetic disturbance that manifests itself in performance degradation, malfunction, or lure of electronic equipment. (IEC) | |||||||
| edison screw | ES | ||||||||
| frequency | f | ||||||||
| F or FWD | Forward | ||||||||
| FA | Field accelerating | ||||||||
| FA Field accelerating | |||||||||
| FC | Field contactor | ||||||||
| FD | Field decelerating | ||||||||
| FL | Field-loss | ||||||||
| FM | Frequency meter | ||||||||
| FU | Fuse | ||||||||
| GP | Ground protective | ||||||||
| H | Hoist | ||||||||
| In | current setting of protective device | ||||||||
| It | tabulated current | ||||||||
| IT | earthing system (see 5.2.6) | ||||||||
| Ith | The maximum current which an open contactor or starter ,may be expected to carry continuously without exceeding the temperature rise allowed by the IEC standard This is NOT A load switching rating! |
Eaton: Eaton IEC contactors.pdf (1996) | IEC | ||||||
| Ith | Thermal current (other versions I have seen: conventional free air current) and the temperature is normally specified with the rating. | ||||||||
| Ith | Conventional free-air thermal current (/th) | IEC 60947-2: 4.3.2.1 | IEC | ||||||
| Ith | Conventional free-air thermal current (/th) | IEC 60947-2: 4.3.2.1 | IEC | ||||||
| Conventional free air thermal current Ith | Ith | Conventional free air thermal current Ith The conventional free air thermal current ist the maximum testing current for temperature testing of devices in free air. The conventional free air thermal current must at least correspond to the maximum rated operational current of an open device during an eight hour operation. Free air is understood as air in common interior rooms almost free of airflow and radiation. |
Merz switcgear.pdf | ||||||
| Conventional enclosed thermal current Ithe | Ithe | Conventional enclosed thermal current Ithe Is the manufacturer defined current for temperature testing of the device, when the device is fitted into a specified enclosure. |
Merz | ||||||
| Iz | current carrying capacity | ||||||||
| J | Jog | ||||||||
| k | kilo - one thousand times | ||||||||
| kV | kilovolt (1000 V) | ||||||||
| L | Lower | ||||||||
| L1,L2,L3 | lines of three-phase system | ||||||||
| LS | Limit switch | ||||||||
| LSC | Luminaire Supporting Coupler | UK | |||||||
| M | Main contactor | ||||||||
| m | metre | ||||||||
| m | milli - one thousandth part of | ||||||||
| M | meg or mega - one million times | ||||||||
| M | Main contactor | ||||||||
| m.i. | mineral-insulated | ||||||||
| mA | milliampere | ||||||||
| MCR | Master control relay | ||||||||
| MD | maximum demand | ||||||||
| MS | Master switch | ||||||||
| Off-State Condition | The conditions of a solid-state device when no control signal is applied. | ||||||||
| Off-State Current | The current that flows in a solid-state device in the off-state condition. | ||||||||
| On-State Condition | The condition of a solid-state device when conducting. | ||||||||
| p.d. | potential difference | ||||||||
| PFC | Prospective Fault Current | ||||||||
| PIR | passive infra-red detector | ||||||||
| PSCC | prospective short-circuit current | ||||||||
| resistance (electrical) | R | resistance of supplementary bonding conductor | |||||||
| r.m.s. | root-mean-square (effective value) | ||||||||
| Ra | the total resistance of the earth electrode and the protective conductor onnecting it to exposed conductive parts | ||||||||
| Radio Frequency Interference (RFI).: | RFI | Unwanted electrical energy that has the possibility of producing undesirable effects in the control, its circuits and system. | |||||||
| Rp | resistance of the human body | ||||||||
| s | second - unit of time | ||||||||
| S | conductor cross-sectional area | ||||||||
| Current: Surge Current | A current exceeding the steady state current for a short time duration, normally described by its peak amplitude and time duration. | ||||||||
| time | t | ||||||||
| Voltage: Transient Overvoltage | The peak voltage in excess of steady state voltage for a short time during the transient conditions (e.g., resulting from the operations of a switching device) | ||||||||
| Voltage | U | symbol for voltage (alternative for V) | |||||||
| Voltage | Uac | alternating voltage | |||||||
| Voltage | Udc | direct voltage | |||||||
| Voltage | Uo | phase voltage | |||||||
| Voltage | V | volt - unit of e.m.f. or p.d. | |||||||
| Power (W) | W | watt - unit of power | |||||||
| X | reactance | ||||||||
| Z | impedance (electrical) | ||||||||
| Ze | earth loop impedance external to installation | ||||||||
| Zs | earth fault loop impedance | ||||||||
| Electrical Noise Immunity | The extent to which the control is protected from a stated electrical noise. | ||||||||
| Frequency: Radio Frequency Interference (RFI) | RFI | RFI is used interchangeably with EMI.EMI is a later definition that includes the entire electromagnetic spectrum, whereas RFI is more restricted to the radiofrequency band, generally considered to be between 10k and 10G Hz. (IEC) | |||||||
| AQL Acceptable quality level | AQL | AQL Acceptable quality level | IEC60947-4-1 | Standard | IEC 60947-4-1 | ||||
| EMC Electro magnetc compatibility | EMC | EMC Electro magnetc compatibility | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Short-circuitprotective device | SCPD | Short-circuitprotective device | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Tripping time | Tp | Tripping time | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Rated control circuit voltage | Uc | Rated control circuit voltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Rated operational voltage | Ue | Rated operational voltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Rated rotoroperationalvoltage | Uer | Rated rotoroperationalvoltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Rated stator operational voltage | Ues | Rated stator operational voltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Ratedinsulation voltage | Ui | Ratedinsulation voltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Rated impulse withstand voltage | Uimp | Rated impulse withstand voltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Rated rotor insulation voltage | Uir | Rated rotor insulation voltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Rated statorinsulation voltage | Uis | Rated statorinsulation voltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Power frequency or d.c.recovery voltage | Ur | Power frequency or d.c.recovery voltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Rated control supply voltage | Us | Rated control supply voltage | IEC60947-4-1 | Standard | IEC60947-4-1 | ||||
| Altitude | Refers to the height of the site where the equipment is located, expressed in meters above the sea level. | ||||||||
| Ambient Temperature | Temperature of the air surrounding the unit. | ||||||||
| Auxiliary Circuit | All the conducting parts of a contactor, intended to be included in a circuit different from the main circuit and the control circuit of the contactor e.g. signalization, interlocking circuits etc. | ||||||||
| Control Circuit | All the conducting parts of a contactor (other than the main circuit) included in a circuit used for the closing operation, or opening operation, or both, of the contactor. | ||||||||
| Main Circuit | All the conducting parts of a contactor included in the circuit which it is designed to close or open. | ||||||||
| Coil Operating Range | Expressed as a multiple of the rated control circuit voltage Uc for the lower and upper limits. | ||||||||
| Cycle Duration | Total time of the on-load + off-load period. | ||||||||
| Electrical Endurance | Number of on-load operating cycles (i.e. with current on the main contacts) a contactor can achieve, varies depending on the utilization category. | ||||||||
| Mechanical Endurance | Number of off-load operating cycles (i.e. without current on the main contacts) a contactor can achieve. | ||||||||
| Current: Overcurrent: | A condition of a higher current caused by any abnormality in /on a circuit. GS | Gary | Gary | Gary | |||||
| Current: Overload: | A condition of a higher current not caused by a wiring fault but solely by virtue of what is connected to the, otherwise normal, circuit. | Gary | Gary | Gary | |||||
| Current: Short circuit current | is a condition of a higher current caused specifically by any wiring fault such as insulation breakdown. | Gary | Gary | Gary |
| *As used in website | Search on web site optomised |
| acb, | Air circuit breaker |
| acdrive, | AC drive / frequency inverter/ |
| ammeter, | Ammeter |
| bcharger, | Battery charger |
| cable, | Cable |
| capsensor, | Capacitive sensor |
| capsensor, | Capacitive sensor |
| chover, | Change over switch |
| cnt, | Counter |
| contactor | Contactor |
| conv, | Electronic comms converter |
| eleak, | Earth leakage |
| freq, | Frequency meter |
| genctl, | Generator controller |
| hmi, | Human machine interface |
| indsensor, | Inductive sensor |
| level, | Level control relay |
| mamon, | milli-Amps monitor |
| mcb, | Miniature circuit brekaer |
| mccb, | Moulded case circuit breaker |
| meter, | Meter Mains values |
| mod, | Extension modules |
| module, | Any electornic box with purpose |
| mvmon, | mVolt monitor |
| namsensor, | Namur sensor |
| oload, | Overoad |
| photosensor, | Photo sensor |
| plc, | programmable logic controller |
| Relay, | Relay |
| rhm, | Run hour meter |
| sstarter, | Soft starter |
| tacho, | Tacho (RPM) meter |
| temp, | Temperature controller |
| timer, | Timer |
| Ultsensor, | Ultrasonic sensor |
| vdcmon, | DC voltage monitor |