173. An employer shall—

(a) provide persons at work in workplaces where explosive atmospheres may occur with sufficient and appropriate training with regard to explosion protection, and

(b) ensure that, where required by the explosion protection document—

(i) work in hazardous places is carried out in accordance with written instructions issued by the employer,

(ii) a system of permits to work is applied for carrying out both hazardous activities and activities which may interact with other work to cause hazards and

(iii) permits to work are issued by a competent person responsible for this function, before the activity concerned commences.