WAC 296-52-67230. Initiating systems

Electric systems. (1) Safety switch. A safety switch must be: (a) Placed at intervals in the permanent firing line when firing from a power circuit. (b) Made: (i) So it can only be locked in the "off position"; or (ii) With a short-circuiting arrangement of the firing lines to the detonator circuit. (2) Lighting gap. A lighting gap must be: (a) At least five feet ahead (in the firing system) of the main firing switch, between the switch and power source. (b) Bridged by a flexible jumper cord just before firing the blast.