PDFWAC 296-45-48520
Guarding of rooms containing electric supply equipment.
(1) Rooms and spaces in which electric supply lines or equipment are installed must meet the requirements of this section under the following conditions:
(a) If exposed live parts operating at 50 to 150 volts to ground are located within eight feet of the ground or other working surface inside the room or space;
(b) If live parts operating at 151 to 600 volts and located within eight feet of the ground or other working surface inside the room or space are guarded only by location, as permitted under this section; or
(c) If live parts operating at more than 600 volts are located within the room or space; unless:
(i) The live parts are enclosed within grounded, metal-enclosed equipment whose only openings are designed so that foreign objects inserted in these openings will be deflected from energized parts; or
(ii) The live parts are installed at a height above ground and any other working surface that provides protection at the voltage to which they are energized corresponding to the protection provided by an eight-foot height at 50 volts.
(2) The rooms and spaces must be so enclosed within fences, screens, partitions, or walls as to minimize the possibility that unqualified persons will enter.
(3) Signs warning unqualified persons to keep out must be displayed at entrances to the rooms and spaces.
(4) Entrances to rooms and spaces that are not under the observation of an attendant must be kept locked.
(5) Unqualified persons cannot enter the rooms or spaces while the electric supply lines or equipment are energized.