(1) All lighting in compressed air chambers shall be by electricity only. Wherever practicable there shall be two independent lighting systems with independent sources of supply.

(2) The exterior of all lamp sockets shall be entirely nonmetallic.

(3) All portable incandescent lamps used shall be guarded by a wire cage large enough to enclose both lamp and socket.

(4) All incandescent lamps shall be so placed that they cannot come in contact with any combustible material.

(5) Only heavy insulated or armored wire shall be used for light or power.