172. (1) An employer shall ensure that—

(a) plant, equipment, protective systems and any associated connecting devices are only brought into service if the explosion protection document indicates that they can be safely used in an explosive atmosphere,

(b) necessary measures are taken to prevent confusion between connecting devices,

(c) all necessary measures are taken to ensure that the workplace, work equipment and any associated connecting device made available to employees are—

(i) designed,

(ii) constructed,

(iii) assembled,

(iv) installed,

(v) maintained, and

(vi) operated,

in such a way as—

(I) to minimise the risks of an explosion, and

(II) if an explosion does occur to control or minimise the propagation of the explosion within that workplace, work equipment, or both,

(d) for a workplace referred to in paragraph (c), appropriate measures are taken to minimise the risks to employees from the physical effects of an explosion,

(e) where the risk assessment shows it to be necessary—

(i) it is possible, where power failure can give rise to the spread of additional risks, to maintain equipment and protective systems in a safe state of operation independently of the rest of the installation in the event of power failure,

(ii) manual override by a competent employee is possible in order to shut down the equipment and protective systems incorporated within automatic processes which deviate from the intended operating conditions, provided that this does not compromise safety, and

(iii) on operation of the emergency shutdown, accumulated energy is dissipated as quickly and as safely as possible or isolated so that it no longer constitutes a hazard,

(f) if the explosion protection document drawn up pursuant to Regulation 169(2) does not state otherwise, equipment and protective systems for all places in which explosive atmospheres may occur is selected on the basis of the categories set out in the relevant statutory provisions intended for use in potentially explosive atmospheres, and

(g) in particular, the following categories of equipment are used in the zones indicated in Schedule 10, provided they are suitable for gases, vapours, mists or dusts, or any combination of them, as appropriate—

(i) in zone 0 or zone 20, category 1 equipment,

(ii) in zone 1 or zone 21, category 1 or 2 equipment, and

(iii) in zone 2 or zone 22, category 1, 2 or 3 equipment.

(2) Paragraph (1)(a) applies also to any equipment or protective systems to which the relevant statutory provisions relating to equipment and protective systems intended for use in potentially explosive atmospheres do not apply if their incorporation into an installation can in itself give rise to an ignition hazard.