BS 7924:1999

Committees responsible
      Foreword
0 Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 General
5 Statutory requirements
6 Responsibilities of the manufacturer
7 Responsibilities of the user
8 Responsibilities of the repairer
9 Identification of repaired and overhauled apparatus
10 Reclamation
11 Removal of damaged windings
12 Encapsulated parts
13 Light-transmitting parts
14 Temporary repairs
15 Cleaning agents and finishes
16 Repair of flameproof apparatus (Type "d")
17 Repair of intrinsically safe (IS) apparatus
      (type "i")
18 Repair of increased safety apparatus (type "e")
Annex A (informative) Statutory duties
Bibliography
Figure 1 - Symbols indicating status of repair/overhaul
Table 1 - Resistance of insulation of windings

Provides recommendations for repair, reclamation, overhaul and modification of certified electrical apparatus intended for use in mines susceptible to firedamp.

This British Standard gives recommendations for the repair, overhaul, reclamation and modification of certified electrical apparatus intended for use in mines susceptible to firedamp (defined as “Group I” apparatus in the explosion protection concept standard BS EN 50014:1998).

Maintenance is not covered, other than where this cannot be dissociated from repair and overhaul. It does not give advice on the use of electrical apparatus or the prevention of any hazards other than ignition of an explosive atmosphere. Similarly, it does not give advice on cable entry systems which may require renewal when the apparatus is re-installed.

NOTE 1 Recommendations regarding routine maintenance, and the selection and installation of intrinsically safe electrical apparatus for use in potentially explosive atmospheres in mines, are given in BS 6704.

NOTE 2 The contract between the user and the repairer will need to address other safety-related matters beyond the scope of this document, e.g. prevention of electric shock, electrical protection (overload, short circuit, earth leakage) and electrical/mechanical interlocking.

Clauses 4 to 9 give general recommendations applicable to persons involved in the repair and/or overhaul of electrical apparatus intended for use in potentially explosive atmospheres found in coal mines. They also identify certain specific responsibilities under the Health and Safety at Work etc. Act 1974 [6] as applicable to those who are likely to be concerned with the repair of certified apparatus.

Clauses 10 to 15 cover those aspects of repair and overhaul which are common to all explosion protected apparatus.

Clauses 16 to 18 give recommendations applicable to specific types of explosion protected apparatus. This standard excludes apparatus having the following forms of protection, which is generally considered irreparable: oil immersion “o”; pressurized “p”; powder filling “q”; and encapsulation “m”.

NOTE 3 Apparatus which contains oil is installed in British mines, but such equipment should be repaired in accordance with this standard and that to which it was certified.