BS 6704:1996

This British Standard describes the concept of ensuring electrical safety in hazardous atmospheres in coal mines by means of the type of protection ‘i’ (intrinsic safety), provides background information and gives recommendations on the selection, installation, inspection and testing, and maintenance and repair of intrinsically safe electrical apparatus, systems and networks.

Electrical safety of apparatus installed outside the hazardous atmosphere, or which is safeguarded by a type of protection other than intrinsic safety, is also considered in so far as the selection, installation and maintenance of such apparatus could affect intrinsically safe circuits. Only explosion risks due to the presence of flammable gases and vapours are considered. Combustible dusts are excluded except for coal dust layers which could be ignited by elevated surface temperatures.

Design or performance aspects of intrinsically safe apparatus pertinent to operational safety are not considered.

Includes inspection, testing, maintenance and repair, and competence of personnel in respect of safe practice.