222Use of mains firing

222 Use of mains firing (1) A shot-firer using mains firing must ensure that— (a) the mains circuit has adequate electrical capacity to fire the firing circuit; and (b) the firing switch is installed between the source of electric power and the firing cable; and (c) the switch is protected by a short-circuit device on the cable side to prevent an electrical current entering the firing cable when the switch is open; and (d) the firing switch and the short-circuit device are placed in switchboxes that are— (i) in a fixed and safe position; and (ii) provided with an effective lock from which the key cannot be removed unless the box is closed and locked; and (iii) so constructed that the box can neither be closed nor locked unless the switch or device is in the open position and the short-circuit device is in place. (2) A shot-firer using mains firing must also ensure that— (a) a switchbox has only a single key; and

(b) the key is in shot-firer’s possession and control while he or she is on duty; and (c) the switchbox is locked after a blasting operation.