Etci National Rules For Electrical Installations In Hazardous Locations

This inspection lamp is constructed so that it cannot set off an explosion when surrounded by specified flammable gases or dust.In, hazardous locations (sometimes abbreviated to HazLoc, pronounced HazLōk) are defined as places where fire or explosion hazards may exist due to flammable gases, flammable liquid–produced vapors, combustible liquid–produced vapors, combustible dusts, or ignitable fibers/flyings present in the air in quantities sufficient to produce explosive or ignitable mixtures. Electrical equipment that must be installed in such classified locations should be specially designed and tested to ensure it does not initiate an explosion, due to contacts or high surface temperature of equipment.The introduction of electrical apparatus for signaling or lighting in coal mines was accompanied by electrically-initiated explosions of flammable gas and dust. Technical standards were developed to identify the features of electrical apparatus that would prevent electrical initiation of explosions due to energy or thermal effects. Several physical methods of protection are used. The apparatus may be designed to prevent entry of flammable gas or dust into the interior. The apparatus may be strong enough to contain and cool any combustion gases produced internally. Or, electrical devices may be designed so that they cannot produce a spark strong enough or temperatures high enough to ignite a specified hazardous gas.

Integrating these types of motors can ensure that equipment, facilities, and workers stay protected and machinery is not damaged. Contents.Electrical ignition hazard A household may emit a small, harmless visible spark when switching. In an ordinary atmosphere this arc is of no concern, but if a flammable vapor is present, the arc might start an explosion.

Electrical equipment intended for use in a or either is designed to contain any explosion within the device or is designed not to produce sparks with sufficient energy to trigger an explosion.Many strategies exist for safety in electrical installations. The simplest strategy is to minimize the amount of electrical equipment installed in a hazardous area, either by keeping the equipment out of the area altogether or by making the area less hazardous by process improvements or ventilation with clean air., or non-incendive equipment and wiring methods, is a set of practices for apparatus designed with low power levels and low stored energy. Insufficient energy is available to produce an arc that can ignite the surrounding explosive mixture. Equipment enclosures can be pressurized with clean air or inert gas and designed with various controls to remove power or provide notification in case of supply or pressure loss of such gases. Arc-producing elements of the equipment can also be isolated from the surrounding atmosphere by encapsulation, immersion in oil, sand, etc.

Heat producing elements such as motor winding, electrical heaters, including heat tracing and lighting fixtures are often designed to limit their maximum temperature below the autoignition temperature of the material involved. Both external and internal temperatures are taken into consideration.As in most fields of electrical installation, different countries have approached the standardization and testing of equipment for hazardous areas in different ways. As world trade becomes more important in distribution of electrical products, international standards are slowly converging so that a wider range of acceptable techniques can be approved by national regulatory agencies.Area classification is required by governmental bodies, for example by the U.S.

And compliance is enforced.Documentation requirements are varied. Often an area classification plan-view is provided to identify equipment ratings and installation techniques to be used for each classified plant area. The plan may contain the list of chemicals with their group and temperature rating, and elevation details shaded to indicate Class, Division(Zone) and group combination.

The area classification process would require the participation of operations, maintenance, safety, electrical and instrumentation professionals, the use of process diagrams and material flows, and any pertinent documents, information and knowledge to determine the hazards and their extent and the countermeasures to be employed. Area classification documentations are reviewed and updated to reflect process changes.History Soon after the introduction of electric power into, it was discovered that lethal explosions could be initiated by electrical equipment such as lighting, signals, or motors. The hazard of or methane accumulation in mines was well known by the time electricity was introduced, along with the danger of suspended coal dust. At least two British mine explosions were attributed to an electric bell signal system. In this system, two bare wires were run along the length of a drift, and any miner desiring to signal the surface would momentarily touch the wires to each other or bridge the wires with a metal tool. The of the signal bell coils, combined with breaking of contacts by exposed metal surfaces, resulted in sparks which could ignite methane, causing an explosion.In an industrial plant such as a or, handling of large quantities of flammable liquids and gases creates a risk of leaks. In some cases the gas, ignitable vapor or dust is present all the time or for long periods.

Other areas would have a dangerous concentration of flammable substances only during process upsets, equipment deterioration between maintenance periods, or during an incident. Refineries and chemical plants are then divided into areas of risk of release of gas, vapor or dust known as divisions or zones.The process of determining the type and size of these hazardous areas is called area classification. Guidance on assessing the extent of the hazard is given in the NFPA 497 or NFPA 499 standards published by the for explosive gas or dust atmospheres respectively, or RP 500 and RP 505 standards published by the, and IEC 60079-10-1 or IEC 60079-10-2 standards published by the for explosive gas or dust atmospheres respectively.Division and Zone classification systems The, as published by the, defines area classification and installation principles. The principles of the NEC Division and Zone classification systems are applied in countries around the globe, such as in the United States.Specifically, Article 500 describes the NEC Division classification system, while Articles 505 and 506 describe the NEC Zone classification system. The NEC Zone classification system was created to provide multinational companies with a system that could be harmonized with IEC classification system and therefore reduce the complexity of management.Canada has a similar system with the defining area classification and installation principles. Two possible classifications are described in (CSA) C22.1 Canadian Electrical Code (CEC) Section 18 (Zones) and Appendix J (Divisions).Explosive gas area classifications Typical gas hazards are from hydrocarbon compounds, but hydrogen and ammonia are common industrial gases that are flammable.Class I, Division 1 classified locations An area where ignitable concentrations of flammable gases, vapors or liquids can exist all of the time or some of the time under normal operating conditions.

A Class I, Division 1 area encompasses the combination of Zone 0 and Zone 1 areas. Zone 0 classified locations An area where ignitable concentrations of flammable gases, vapors or liquids are present continuously or for long periods of time under normal operating conditions. An example of this would be the vapor space above the liquid in the top of a tank or drum. The ANSI/NEC classification method consider this environment a Class I, Division 1 area. As a guide for Zone 0, this can be defined as over 1000 hours/year or 10% of the time. Zone 1 classified location An area where ignitable concentrations of flammable gases, vapors or liquids are likely to exist under normal operating conditions.

As a guide for Zone 1, this can be defined as 10–1000 hours/year or 0.1–10% of the time. Class I, Division 2 or Zone 2 classified locations An area where ignitable concentrations of flammable gases, vapors or liquids are not likely to exist under normal operating conditions. In this area the gas, vapor or liquids would only be present under abnormal conditions (most often leaks under abnormal conditions).

As a general guide for Zone 2, unwanted substances should only be present under 10 hours/year or 0–0.1% of the time. Unclassified locations Also known as non-hazardous or ordinary locations, these locations are determined to be neither Class I, Division 1 or Division 2; Zone 0, Zone 1 or Zone 2; or any combination thereof. Such areas include a residence or office where the only risk of a release of explosive or flammable gas would be such things as the propellant in an.

The only explosive or flammable liquid would be paint and brush cleaner. These are designated as very low risk of causing an explosion and are more of a fire risk (although gas explosions in residential buildings do occur). Unclassified locations on chemical and other plant are present where it is absolutely certain that the hazardous gas is diluted to a concentration below 25% of its lower (or lower explosive limit (LEL)). Explosive dust area classifications.

An explosion of dust at this in Kansas killed five workers in 1998.Flammable when suspended in air can explode. An old system of area classification to a British standard used a system of letters to designate the zones. This has been replaced by a European numerical system, as set out in directive 1999/92/EU implemented in the UK as the Dangerous Substances and Explosives Atmospheres Regulations 2002The boundaries and extent of these hazardous locations should be decided by a competent person. There must be a site plan drawn up of the factory with the divisions or zones marked on.NEC:Class II, Division 1 classified locations An area where ignitable concentrations of combustible dust can exist all of the time or some of the time under normal operating conditions. Class II, Division 2 classified locations An area where ignitable concentrations of combustible dust are not likely to exist under normal operating conditions.

Class III, Division 1 classified locations An area where easily ignitable fibers or materials producing combustible flyings are handled, manufactured or used. Class III, Division 2 classified locations An area where easily ignitable fibers are stored or handled.Outside America:Zone 20 classified locations An area where ignitable concentrations of combustible dust or ignitable fibers/flyings are present continuously or for long periods of time under normal operating conditions. Zone 21 classified location An area where ignitable concentrations of combustible dust or ignitable fibers/flyings are likely to exist under normal operating conditions. Zone 22 classified locations An area where ignitable concentrations of combustible dust or ignitable fibers/flyings are not likely to exist under normal operating conditions. Unclassified locations Also known as non-hazardous or ordinary locations, these locations are determined to be neither Class II, Division 1 or Division 2; Class III, Division 1 or Division 2; Zone 20, Zone 21 or Zone 22; or any combination thereof. Gas and dust groups Explosive atmospheres have different chemical properties that affect the likelihood and severity of an explosion.

Such properties include flame temperature, minimum ignition energy, upper and lower explosive limits, and molecular weight. Empirical testing is done to determine parameters such as the (MESG), minimum igniting current (MIC) ratio, explosion pressure and time to peak pressure, spontaneous ignition temperature, and maximum rate of pressure rise. Every substance has a differing combination of properties but it is found that they can be ranked into similar ranges, simplifying the selection of equipment for hazardous areas.Flammability of combustible liquids are defined by their flash-point. The flash-point is the temperature at which the material will generate sufficient quantity of vapor to form an ignitable mixture. The flash point determines if an area needs to be classified. A material may have a relatively low autoignition temperature yet if its flash-point is above the ambient temperature, then the area may not need to be classified.

Mark for ATEX certified electrical equipment for explosive atmospheres.In Europe the label must show the and the code number of the certifying body. The CE marking is complemented with the Ex mark (yellow filled hexagon with greek letters epsilon chi), followed by the indication of the Group, Category and, if group II equipment, the indication relating to gases (G) or dust (D). For example: Ex II 1 G (Explosion protected, Group 2, Category 1, Gas) Specific type or types of protection being used will be marked. Ex ia IIC T4. (Type ia, Group 2C gases, Temperature class 4). Ex nA II T3 X (Type n, non-sparking, Group 2 gases, Temperature class 3, special conditions apply).Industrial electrical equipment for hazardous area has to conform to appropriate parts of standard for gas hazards, and for dust hazards, and in some cases, be certified as meeting that standard.

Hazardous Location Definition

Independent test houses (known as ) are established in most European countries, and a certificate from any of these will be accepted across the EU. In the United Kingdom, the DTI appoint and maintain a, of which and are the most well known.Australia and New Zealand use the same IEC 60079 standards (Adopted as AS/NZS 60079) however the CE mark is not required.North America In North America the suitability of equipment for the specific hazardous area must be tested by a.

Such institutes are, or (ETL), for example.The label will always list the Class(es), Division(s) and may list the Group(s) and temperature Code. Directly adjacent on the label one will find the mark of the listing agency.Some manufacturers claim 'suitability' or 'built-to' hazardous areas in their technical literature, but in effect lack the testing agency's certification and thus unacceptable for the AHJ to permit operation of the electrical installation/system.All equipment in Division 1 areas must have an approval label, but certain materials, such as rigid metallic conduit, does not have a specific label indicating the Cl./Div.1 suitability and their listing as approved method of installation in the NEC serves as the permission. Some equipment in Division 2 areas do not require a specific label, such as standard 3 phase induction motors that do not contain normally arcing components.Also included in the marking are the manufacturers name or trademark and address, the apparatus type, name and serial number, year of manufacture and any special conditions of use. The NEMA enclosure rating or may also be indicated, but it is usually independent of the Classified Area suitability.See also. competency standard.References. Article 500 of the National Electrical Code (NEC), NFPA 70.

Retrieved 2018-04-04. Bossert 86 page 17. National Fire Protection Association. ^.

UK Health and Safety Executive. 22 September 2004. John Bossert and Randolph Hurst, Hazardous Locations A Guide for the Design, Construction and Installation of Electrical Equipment, Canadian Standards Association, Toronto 1986, Chapter 9. IAEI Magazine. Retrieved 2018-04-04.

Research, OZM. Retrieved 2018-04-04.Further reading. Alan McMillan, Electrical Installations in Hazardous Areas, Butterworth-Heineman 1998,. Peter Schram Electrical Installations in Hazardous Locations, Jones and Bartlett, 1997,. EEMUA, A Practitioner's Handbook for potentially explosive atmospheres, The Engineering Equipment and Materials Users Association, 2017.

Hazardous Classified Locations

The Electricity Regulation Act 1999, as amended, makes it mandatory for a to issue a Completion Certificate for all. If a REC carries out minor electrical works they must be certified if requested by the customer.It is through this certification system that Safe Electric, can monitor and validate that the electrical works completed meet the required safety standards (National Rules for Electrical Installations).To facilitate the wide range of electrical works undertaken by RECs, the different types of Completion Certificates are outlined below:(.