This part of IEC 60079-35 specifies requirements for the construction, testing and marking of caplights, including caplights with a point of connection for other equipment, for use in mines susceptible to firedamp (Group I – electrical equipment for explosive gas atmospheres as defined in IEC 60079-0). It deals only with the risk of the caplight becoming a source of ignition.

The requirements for performance are in IEC 60079-35-2.¹

This standard supplements and modifies the general requirements of IEC 60079-0 except as indicated in Table 1. Where a requirement of this standard conflicts with a requirement of IEC 60079-0, the requirements of this standard take precedence.

Compliance with this standard will provide an EPL of Mb (see 4.1 of this standard). If an EPL of Ma is required, the caplight will need to conform to the requirements of 4.2 of this standard, which in turn refers to IEC 60079-11.

It is expected that from time to time, caplights conforming to this standard (EPL Mb) will operate in atmospheres where the firedamp exceeds statutory levels that require the withdrawal of people from the high firedamp atmosphere to a non-hazardous area.

In designing equipment for operation in conditions other than those given above, this standard may be used as guidance; however, additional testing may be required.

Where a caplight is assessed as intrinsically safe equipment, Ex ia, conforming to IEC 60079- 11 only the clauses/subclauses listed in 4.2 require application.

¹ IEC 60079-35-2, Caplights for use in mines susceptible to firedamp – Part 2: Performance and other safetyrelated matters (to be published).