NFPA 70 NEC Articles 500 through 503 cover the requirements for electrical/electronic equipment and wiring for all voltages in Class I, Divisions 1 and 2; Class II, Divisions 1 and 2; and Class III, Divisions 1 and 2 locations. This level of risk is represented by classifying the hazardous area as Zone 0, Zone 1 or Zone 2 (for gas, vapour and mist atmospheres) or Zone 21 or Zone 22 for dust atmospheres. (between 0,1 and 10% of the time). Definition of hazardous area zones (AS/NZS 60079.10): Zone 0 7: For further information on application of electrical, Informational Note No. Zone 0: flammable atmosphere highly likely to be present - may be present for long periods or even continuously . WHEN YOU NEED THEM. Shown below is a summary of the applicable NEC Articles to reference to ensure the proper requirements are applied. A high level of protection is ensured. Area (mm2) CFD BS EN 60079-10-1:2009 1 5.0 5.0 0.0936 12.3 - 61.7 2 5.0 2.5 0.0326 6.17 - 30.8 Although every application is different, for the ease of monitoring and specification each hazardous area is classified as a particular level or zone. Zone 1 . Zones also have the added benefit of including the area classification with the zone description. December 2020 Photo 2. Equipment used in hazardous area must comply to certain Ex standards. Area which are not devided into Atex zones, are called non-hazardous area's. Class / Division System In Northerm America, instead of the zone classification system, the Class/Division system is used. To minimize the risk of these fires or explosions, electrical/electronic equipment must be designed, tested and labeled as being acceptable for use in the areas in which it is installed. . This level of risk is represented by classifying the hazardous area as Zone 0, Zone 1 or Zone 2 (for gas, vapour and mist atmospheres) or Zone 21 or Zone 22 for dust atmospheres. Sources of The Zone Classification System is offered as an alternative to the Class and Division system. | For Dust this would be Zone 21. 1910.307 (g) (2) Equipment should be tested to ensure that it does not exceed 80%[according to whom?] In the United States, the NEC uses 2 different classifications: Hazardous areas are classified into zones based on an assessment of the frequency of the occurrence and duration of an explosive gas atmosphere, as follows: Zone 0: An area in which an. Gases, Vapors and Mists. Equipment is non-incendive or non-sparking. Zone 1 - Explosive atmospheres are likely to occur. FEA Hazardous Area Classification is a study, in which is assessed, at witch locations of a plant, factory or company, high concentrations of flammable gases are present or can be released, in order to create an explosion hazard. * Zone 1 a location in which explosive gas atmospheres are likely to occur during normal operation, or which is adjacent to a Zone 0 location. Equipment of the nonheat-producing type, such as junction boxes, conduit, and fittings, and equipment of the heat-producing type having a maximum temperature not more than 100 C (212 F) need not have a marked operating temperature or temperature range; Electric equipment suitable for ambient temperatures exceeding 40 C (104 F) shall be marked with both the maximum ambient temperature and the operating temperature or temperature range at that ambient temperature; and. may exist under normal or abnormal conditions because of the presence of flammable gases or vapors, combustible dusts or ignitable fibers or flyings. Within the European Union, these are defined by IEC/EN standards (IEC/EN 60079-10-1 or 2) as directed by ATEX. These are typically process areas where gases are more likely to be present. Type of protection "n" is further subdivided into nA, nC, and nR. . For equipment provided with threaded entries for NPT threaded conduit or fittings, listed conduit, conduit fittings, or cable fittings shall be used. When the concentration of methane is beneath the LEL, an explosion cannot occur, even when an ignition source is present. The Class/Division/Group system is based on Article 500 of the National Electrical Code (NEC) where. July 2019 The simplest is to minimize the amount of electrical equipment installed in a hazardous location, either by keeping the equipment out of the area altogether, or by making the area less hazardous (for example, by process changes, or ventilation with clean air). Pressurised Container Flameproof "d" - This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. The prevention of explosions in working environments is in most countries regulated in national laws and directives. This means that the electrical equipment is safe for use within these area by applying special protection strategies. In other cases, the atmosphere is normally non-hazardous, but a dangerous concentration can be reasonably foreseensuch as operator error or equipment failure. Class defines the general nature (or properties) of the hazardous material in the surrounding atmosphere. Directly adjacent on the label one will find the mark of the listing agency. The escaping (hot) gases must sufficiently cool down along the escape path that by the time they reach the outside of the enclosure not to be a source of ignition of the outside, potentially ignitable surroundings. February 2022 . What Are All Those Gadgets On A Multitool? For specific industries, the specific codes for that industry are important to use. No other aspect of safety receives more attention in the form of codes and standards. the National Fire Protection Association (NFPA) 70, National Electric Code(NEC). These generally give rise to areas classied as Zones 0, 1, and 2 respectively. Many people have heard terms like Class I, Division 2, Group E, or ATEX zone 21 but many of our customers only know what certification they require with little understanding of what they mean, so we thought it would be appropriate to write a blog post to help customers understand the broader implications of these terms. The flash-point is the temperature at which the material will generate sufficient quantity of vapor to form an ignitable mixture. For example, a socket outlet labeled EEx'de' might have a case made to EEx 'e' and switches that are made to EEx 'd'. These areas only become hazardous in case of an accident or some unusual operating condition. So, it is good to know that when a flammable substance concentration exceeds the LEL, it will not automatically lead to an explosion with the highest Pmax. All rights reserved. Zone 0, 1 2 . For non-ambient conditions, like process reactors or other enclosed systems, the Limiting Oxygen Concentration is often used for the prevention of explosive atmospheres within those enclosed areas. CUTTING SKIPS The IEC standard EN 60079-33 is made public and is expected to become effective soon, so that the normal Ex certification will also be possible for Ex-s, Zone depending upon manufacturer's certification, explosive atmosphere between 10 and 1000 hrs/yr, explosive atmosphere between 1 and 10 hrs/yr, explosive surface between 10 and 1000 hrs/yr, explosive surface between 1 and 10 hrs/yr, Certified and labeled for use in indoor locations rated NEC Class I, Groups A, B, C, and D, Certified and labeled for use in locations rated NEC Class I, Groups A, B, C, and D; both indoors and outdoors, Certified and labeled for use in locations rated NEC Class II, Groups E, F, or G, Explosion protected, Group 2, Category 1, Gas, Type ia, Group 2C gases, Temperature class 4, Type n, non-sparking, Group 2 gases, Temperature class 3, special conditions apply. A Zone 1 hazardous area is classified as a place in which an explosive atmosphere consisting of a mixture with air or flammable substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally. Conversely if the same material is heated and handled above its flash-point, the area must be classified for proper electrical system design, as it will then form an ignitable mixture.[5]. Purged and pressurized -- This protection technique is permitted for equipment in the Class I, Zone 1 or Zone 2 locations for which it is approved. The equipment group . In instances of areas within the same facility classified separately, Class I, Zone 2 locations may abut, but not overlap, Class I, Division 2 locations. But every hazardous area is different and each has specific requirements depending on the nature of the atmosphere and the elements that are present. TLS OFFSHORE CONTAINER Temporary Refuge ), Group F Carbon-based (eg. November 2021 December 2021 Atmospheres containing acetylene, hydrogen, carbon disulphide or gases and vapors of equivalent hazard. The plan may contain the list of chemicals with their group and temperature rating. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. [1] NEC article 500 describes the NEC Division classification system, while articles 505 and 506 describe the NEC Zone classification system. EN 16985 concerning spray cabins and powder coating cabins, EN 12779 related to extraction systems for hot sawdust and chips, EN 60079-10 series, 2020 version for gas and dust explosion hazard, NPR 7910 series for gas and dust explosion hazard based on EN 60079-10-1, 2015 version, EN 13617 for fuel dispensers at filling stations. Hazardous Environment Classifications: NEC vs IEC, IEC (International Electrotechnical Commission), Group E Metal dusts (eg. September 2020 .14 . Explosion-proofing designs equipment to contain ignition hazards, prevent entry of hazardous substances, and, contain any fire or explosion that could occur. Methane has a UEL of 17 vol%, which means when the concentration of methane in air is above the 17 vol% an explosion cannot occur even when an ignition source is present. [12], International Electrotechnical Commission, Occupational Safety and Health Administration, National Electrical Manufacturers Association, "Hazardous Area Classification and Control of Ignition Sources", "Hazardous (Classified) Locations NEC Articles 500 through 517", https://en.wikipedia.org/w/index.php?title=Electrical_equipment_in_hazardous_areas&oldid=1134828101, ignitable concentrations of combustible dust can exist, under normal conditions, ignitable concentrations of combustible dust are unlikely to exist normally, ignitable fibers, or materials producing combustible flyings, are handled, manufactured or used, easily ignitable fibers are stored or handled. Controls can be fitted to detect dangerous concentrations of hazardous gas, or failure of countermeasures. D8.1.3 Hazardous areas are subdivided into Zones 0,1 or 2, the definitions of each cate-gory being as follows: Zone 0 an area in which an explosive gas-air mixture is continuously present or present for long periods. September 2019 Zone 0 (hazardous area) An area in which an explosive gas-air mixture is continuously present or present for long periods. October 2018 It is created based on input from the Process Flow Diagrams, Piping & Instrumentation Diagrams and the Equipment Location Plan . September 2021 Hazardous areas are those defined as areas of potential explosion risk due to the presence of flammable gas or vapor. The overpressure is monitored, maintained and controlled. d : HA - ha ea OA - oa Area classification - Divisions vs. zones Continuous hazard Intermittent hazard Hazard under abnormal conditions Zone 0 Zone 1 Zone 2 Division 1 Division 1 Division 2 Hazardous locations - CEC classifications Class I LIFTING TEST In recent years also the EPL is specified for several kinds of protection. Comparison of Zone 2 and Division 2 TABLE 1 - AREA CLASSIFICATIONS Division 1: Where ignitable concentrations can exist all of the time or some . a headlamp, rather than a dedicated fixed luminaire. Area classification is not simply intended to identify hazardous areas on process plants where design has already been completed using only operational and economic factors as influence,. The more hazardous the area to more safety measures have to be taken in order to prevent equipment becoming an effective source of ignition. area in which an explosive gas atmosphere is likely to occur occasionally in normal operation. Zone 0, 1, and 2 locations are those in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitible mixtures. PROCESS OF CONTAINER Exception No. 1: As a guide to classification of Zone 22 locations, refer to ANSI/ISA 60079-10-2 (12.10.05)-2013, Explosive Atmospheres Part 10-2: Classification of areas Combustible dust atmospheres. These applications will - due to browser restrictions - send data between your browser and our server. >> For Gas Vapor this would be Zone 1. The International Electrotechnical Commission publishes the 60079 series of standards[2] which defines a system for classification of locations, as well as categorizing and testing of equipment designed for use in hazardous locations, known as "Ex equipment". hazardous areas as the following: An area where a potential hazard (e.g., a fire, an explosion, etc.) The NEMA enclosure rating or IP code may also be indicated, but it is usually independent of the Classified Area suitability. June 2020 Zone 22 Zone 21 Zone20 A hazardous atmosphere formed by dust cloud in air is not likely to occur in . I Flammable gases or vapors may be present, 1 Ignitable concentrations of hazards exist under normal operation conditions and/or where the hazard is caused by frequent maintenance or repair work or frequent equipment failure, E Combustible metal dusts: aluminum, commercial alloys and magnesium, III Easily ignitable fibers or flyings may be present, 0 Ignitable concentrations of flammable gases or vapors which are present continuously or for long periods of time, 1 Ignitable concentrations of flammable gases or vapors which are likely to occur under normal operating conditions; may exist frequently because of repair/maintenance operations or leakage; or equipment is operated in a manner that equipment breakdown/faulty operations could result in the release of ignitable concentrations of flammable gases or vapors and failure of the equipment, 2 Ignitable concentrations of flammable gases or vapors which are not likely to occur under normal operating conditions and if they do will only persist for a short period of time; or volatile flammable liquids, gases, or vapors are confined within closed containers/systems and can escape only as a result of an accidental rupture; or volatile flammable liquids, gases, or vapors are normally prevented by positive mechanical ventilation, but may become hazardous due to system failure, 20 Combustible dusts or ignitable fibers/flyings are present continuously or for long periods of time, 21 Combustible dusts or ignitable fibers/flyings are likely to occur under normal operating conditions; or may exist frequently because of repair/maintenance operations or leakage; or equipment is operated in a manner that breakdown/faulty operations could result in the release of ignitable concentrations of combustible dust or fibers/flyings and failure of the equipment, 22 Combustible dusts or ignitable fibers/flyings are likely to occur under normal operating conditions; or may exist frequently because of repair/maintenance operations or leakage; or equipment is operated in a manner that breakdown/faulty operations could result in the release of ignitable concentrations of combustible dust or fibers/flyings and failure of the equipment, Mines susceptible to firedamp (flammable mixture of gases naturally occurring in a mine, Explosive dusts Group III equipment is subdivided into three subgroups, A Atmospheres containing acetone, ammonia, ethyl alcohol, gasoline, methane, propane, or gases/vapors of equivalent hazard, A Atmospheres containing solid particles and fibers greater than 500 microns that could be suspended in air and settle out, B Atmospheres containing acetaldehyde, ethylene, or gases / vapors of equivalent hazard, B Atmospheres containing combustible dusts other than combustible metal dusts, C Atmospheres containing acetylene, hydrogen, or gases/vapors of equivalent hazard, C Atmospheres containing combustible metal dusts. IEC 60079-10.1 Classification of areas - Explosive gas atmospheres. Equipment provided with threaded entries for field wiring connection shall be installed in accordance with paragraph (g)(2)(iv)(A) or (g)(2)(iv)(B) of this section. Category 3 equipment may only be used in zone 2 areas. In some cases, the hazardous atmosphere is present all the time, or for long periods. Groups E, F, and G are for dusts and flyings (Class II or III). The substance referred to by classhas a low probability of producing an explosive or ignitable mixture and is present only during abnormal conditions for a short period of time - such as a container failure or system breakdown. It is always balancing between not defining such areas too large (with highly costs for prevention of ignition sources) or too small (unsafe situations). Groups A, B, C, and D are for gases (Class I only). The Zone system has wider use in the chemical and petrochemical industries. The relation between that system and de zone classification system is clarified within the following table (only for gases and liquids are displayed, not for dusts and fibers). The specific hazardous materials within each group and their automatic ignition temperatures can be found in Article 500 of the National Electrical Code and in NFPA 497. (equivalent to NEC Class I, Groups A and B), (equivalent to NEC Class II, Groups F and G), Group IIC is the most severe zone system gas group. Powder Filling "q" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved. Note to paragraph (c)(2)(i) of this section: NFPA 70, the National Electrical Code, lists or defines hazardous gases, vapors, and dusts by "Groups" characterized by their ignitable or combustible properties. No representation is made that the information or references are complete or remain current. These generally give rise to areas classied as Zones 0, 1, and 2 respectively. The value is represented is volume percentage of oxygen. Note to paragraph (c)(3) of this section: The National Electrical Code, NFPA 70, contains guidelines for determining the type and design of equipment and installations that will meet this requirement. Electrical equipment can and does cause fires and/or explosions in certain atmospheres. Hazards in this group gas can be ignited very easily indeed. NFPA 70 NEC Classes, Divisions and Groups. Equipment shall be marked to show the class, group, and operating temperature or temperature range, based on operation in a 40-degree C ambient, for which it is approved. We don't collect information from our users. . An area where combustible dusts or ignitable fibers and flyings are likely to occur under normal operating conditions. A special standard for instrumentation is IEC/EN 60079-27, describing requirements for Fieldbus Intrinsically Safe Concept (FISCO) (zone 0, 1 or 2) (This special standard has been withdrawn, and has been partially replaced by: IEC/EN60079-11:2011 and IEC/EN60079-25:2010)[1], A special standard for instrumentation is IEC/EN 60079-27, describing requirements for Fieldbus Non-Incendive Concept (FNICO) (zone 2) (This special standard has been withdrawn, and has been partially replaced by: IEC/EN60079-11:2011 and IEC/EN60079-25:2010)[9]. Accommodation Cabin July 2022 Australia and New Zealand use the same IEC-60079 standards (adopted as AS/NZS60079), however the CE mark is not required. Google use cookies for serving our ads and handling visitor statistics. Group define the type of hazardous material and (partly) the location of the surrounding atmosphere. Zone 1 an area in which an explosive gas-air mixture is likely to occur in normal operating conditions. SEWAGE TREATMENT The hazardous area classification system determines required protection techniques and methods for electrical installations in the location. The Occupational Safety and Health Administration (OSHA) has adopted these hazardous classifications and all except Groups are defined in 29 Code of Federal Register (CFR) 1910.399. October 2020 1.1.2 This recommended practice provides information on specific flammable gases and vapors, flammable liquids . - 1 2 (Class 1, . Safety is ensured in the event of frequently occurring disturbances or equipment faults which normally have to be taken into account. Temporary Refuge (TR) Shelter A light switch may cause a small, harmless spark when switched on or off. Temperature Control NEC 2 Divisions (Div 1 2) Division I Comprising of Area Same as Zone 0 1. The zone classification for gases is divided into three zones, namely Zone 0, Zone 1 and Zone 2 and for dusts Zone 20, Zone 21 and Zone 22. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. In effect it is any method which can be shown to have the required degree of safety in use. National Electrical Code, NFPA 70, Chapter 5, Article 500, 29 CFR 1910 Subpart S, Electrical 1910.307, NFPA 497, "Classification of Gases, Vapors, and Dusts for Electrical Equipment in Hazardous Classified Locations", NFPA Handbook, "Electrical Installations in Hazardous Locations, " by P. J. Schram and M. W. Earley, NFPA 70E, Chapter 5, "Hazardous (Classified) Locations", ANSI/UL 913, "Intrinsically Safe Apparatus", NFPA 496, "Purged and Pressurized Enclosure for Electrical Equipment in Hazardous Locations.