Electrical installation explosive atmospheres

BS 5345. General Recommendations—Code of Practice for Selection, Installation and Maintenance of Electrical Apparatus for Use in Potentially Explosive Atmospheres. BSI, U.K. 

Electrical apparatus for explosive gas atmospheres. Electrical installations in hazardous areas (other than mines) 5571/1991 BS EN 60079-14/1997 ... 

FPN No. 1) As a guide in determining when flammable gases are present continuously, for long periods, or under normal conditions, refer to. Recommended Practice for Classification of Locations for Electrical Installations of Petroleum Facilities, API RP 500-1991, Electrical Apparatus for Explosive Gas Atmospheres, Classifications of Hazardous Areas, lEC 79-10 and. Institute of Petroleum Area Classification Code for Petroleum Installations, IP 15. 

Withdrawn) 1989 AMD 3 Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosives processing and manufacture). Part 1 General recommendations (AMD 7871) dated 15 September 1993. Withdrawn, superseded by BS EN 60079-14 1997 (Withdrawn) 1978 AMD 1 Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosives processing and manufacture). Part 6 Recommendations for type of protection. Increased safety (AMD 5557) dated 30 November 1989. Withdrawn, superseded by BS EN 60079... 

AMD 1 Electrical apparatus for explosive gas atmospheres. Electrical installations in hazardous areas (other than mines). Corrigendnm No. 1 (Corr. 10013) dated April 1998, superseded BS 5345 Part 1 1989, Parts 2 and 7 1979, Part 4 1977, Part 5 1983, Part 6 1978 and Part 8 1980... 

Installation and maintenance of electrical apparatus for use in potentially explosive atmospheres. 

When installing conductive nonmetallic piping and metallic pipe with nonmetallic linings, consideration should be given to the need to provide electrical continuity throughout the system and to grounding requirements. This is particularly critical in areas with potentially explosive atmospheres. 

Due to the quite different structures of industrial plants equipped with electrical installations, there are different probabilities for the existence of potentially explosive atmospheres formed by gas-air, vapour-air or dust-air mixtures. With respect to economical reasons, the types of explosion protection for electrical apparatus and systems will depend strongly on the explosion risk at the installation point. It is very unusual to construct and build all explosion protected electrical apparatus in such a manner that they can operate permanently in a surrounding hazardous atmosphere with combustible gases, vapours and dusts in air. The common way is to classify different areas in industrial plants according to the probability for the existence of a hazardous atmosphere and to establish adequate types of explosion protection. In other words, industrial plants with potentially explosive atmospheres are divided and classified into zones. ... 

Code of practice for the installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosives processing and manufacture), 8 parts. 

Electrical installations in explosive gas atmospheres (other than mines). 

All electrical installations and installed equipment must be safe to use and free from the dangers of electric shock, but some installations or locations require special consideration because of the inherent dangers of the installed conditions. The danger may arise because of the corrosive or explosive nature of the atmosphere, because the installation must be used in damp or low-temperature conditions or because there is a need to provide additional mechanical protection for the electrical system. Part 7 of the lET Regulations deals with these special installations or locations. In this section we will consider some of the installations which require special consideration. 

Part 5, Section 5.1 1982 Halon 1301 total flooding systems BS 5345 Code of Practice for the selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres Part 1 1976 Basic requirements for all parts of the code BS 5423 1987 Specification for portable fire extinguishers BS 5499 Fire safety signs, notices and graphic symbols Part 1 1984 Specification for fire safety signs BS 5839 Fire detection and alarm systems in buildings Part 1 1980 Code of Practice for installation and servicing BS 5908 1980 Code of Practice for fire precautions in chemical plant... 

The construction of electrical equipment to be used where a flammable or explosive atmosphere is likely to occur must be such as to prevent ignition of that atmosphere. The selection and installation of such equipment is a detailed and specialised matter requiring expert knowledge. Guidance may be obtained from HSE publication HS(G)22 BS5490 , BS5345 and BS5501 ... 

Before electrical equipment is installed in any location where flammable dusts vapours or gases may be present, the area must be zoned in accordance with the Dangerous Substances and Explosive Atmospheres Regulations and records of the zoned areas must be marked on building drawings and revised when any zoned area is changed. The installation and maintenance of electrical equipment in potentially flammable atmospheres is a specialized task. It must only be undertaken by electricians or instrument mechanics who have an understanding of the techniques involved. 

The relevant standards have been affected by the standard harmonisation process within the EU through the European Committee for Electrotechnical Standardisation (CENELEC) and through the International Electrotechnical Commission (lEC). Individual parts of BS EN 60079 deal with different aspects concerning electric apparatus for potentially explosive gas atmospheres, namely classification of hazardous areas, electrical installations in hazardous areas (other than mines) and inspection and maintenance of electrical installations in hazardous areas (other than mines). BS 50014 covers general requirements. 

Two important EU directives, referred to as the ATEX directives (ATEX 100a and ATEX 137), have been introduced concerning equipment and installations in potentially explosive atmospheres. One is an equipment directive covering tiie design and manufacture of equipment for use in hazardous areas the otiier is a users directive dealing with the use and operation of equipment in hazardous areas. These direchves apply to non-electrical as well as to electrical equipment. All equipment and components intended for use in potentially explosive atmospheres (gases, vapours, mists or dusts) need to comply with the requirements of these directives. Certification will be xmdertaken throughout the EU to common rules and procedures. 

Electrical equipment installed in flammable or dust-laden explosible atmospheres needs to be selected so that it cannot act as an ignition source. This requires hazardous areas to be classified according to the likelihood of a flammable or explosible atmosphere being present, and then suitable equipment being selected, installed and maintained by competent persons. Detailed information on the requirements is contained in Chapter 15. 

Diagnose and rectify causes of electrical fault to restore effective performance on equipment installed in potentially explosive atmospheres. 

Rooms where batteries shall be charged are not under the rules for rooms with explosive atmosphere. The electrical installation and illumination equipment have to correspond to the standards for wet room installation. A minimum distance of 0.5 m between cells and electric spark-generating sources is strictly required. 

In those areas of a process plant where a potentially explosive atmosphere can be present, special measures must be taken in the design of the plant, in the selection of electrical materiel and in its site installation. At the design stage the hazardous areas are classified into zones in accordance with the likelihood of an explosive atmosphere being formed. The response to these risks is ... 

Work in damp or wet conditions, including sewers, tunnels and quarries Where there is an increase to the designed/planned load Work in flammable and potentially explosive atmospheres Following design changes to electrical installation and equipment... 

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