RCW 49.24.360

Insulators required.

(1) All underground cables and wires, unless provided with grounded metallic covering, shall be supported by efficient insulators. The conductors connecting lamps to the power supply shall in all cases be insulated.
(2) Cables and wires unprovided with metallic coverings shall not be fixed to walls or timbers by means of uninsulated fastenings.
[ 1941 c 194 § 29; Rem. Supp. 1941 § 7666-37.]