BS 6704:1996

Committees responsible
Foreword
Code of Practice
Section 1. General
1.1 Scope
1.2 References
1.3 Definitions
1.4 Information on legislation
1.5 Information on certification
1.6 Information on certification of electrical
      apparatus and systems
1.7 Marking of apparatus certified to BS 5501 Part 7
Section 2. Selection and installation of electrical
apparatus and systems
2.1 Selection
2.2 Installation
Section 3. Inspection and testing
3.1 General
3.2 Inspection
3.3 Routine inspection
3.4 Insulation and earth continuity testing
3.5 Records
Section 4. Maintenance and repair
4.1 General
4.2 Maintenance work in a hazardous area
4.3 Maintenance work in a non-hazardous area
4.4 Cable disconnection
4.5 Batteries
4.6 Electrical measuring instruments
4.7 Repair and overhaul
Annexes
A (normative) Competence of personnel
B (informative) Characteristics of mining type cables
Tables
1 Standards dealing with the design, construction and
      testing of electrical apparatus for use in
      hazardous atmospheres
B.1 Telephone cable inductance and resistance ratios
      (nominal values)
B.2 Signalling cable inductance and resistance ratios
      (nominal values)
B.3 Electrical characteristics of pliable wire
      armoured cables to BS 6708:1991 (nominal values)
B.4 Electrical characteristics of two-core steel wire
      armoured cables to BS 6708:1991 (nominal values)
Figures
1 Certification mark
2 Example of marking of apparatus for connection
      to other apparatus and which does not incorporate
      a power source
3 Example of marking of a mains driven power supply
      unit contained within a flameproof enclosure
List of references

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

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.