(1) All lighting underground shall be by electricity.

(a) Lighting shall comply with chapter 296-155 WAC.

(b) Power equipment shall comply with chapter 296-155 WAC.

(2) Emergency lighting. The lighting circuits shall be connected to two independent sources of power supply. In addition to the lighting circuit, adequate and sufficient portable electric emergency lights shall be provided and maintained for immediate use. These shall be readily accessible to all employees working underground.

(3) Lamp sockets. The exterior of all lamp sockets shall be of nonmetallic material and all sockets shall be of the weatherproof type.

(4) Location of lamps. Lamps shall be so placed that they cannot come into contact with combustible materials and so that a clear space is provided all around.

(5) Lamp guards. All lamps shall be protected with wire cage guards.