RCW 49.24.310
Telephone system for tunnels.
Where tunnels are driven from shafts more than two hundred and fifty feet deep, a telephone system shall be established and maintained, communicating with the surface at each such shaft, and with a station or stations readily and quickly accessible to the men at the working level.
[ 1941 c 194 § 24; Rem. Supp. 1941 § 7666-32.]
Structure Revised Code of Washington
Chapter 49.24 - Health and Safety—Underground Workers.
49.24.020 - Compressed air safety requirements.
49.24.030 - Medical and nursing attendants.
49.24.040 - Examination as to physical fitness.
49.24.080 - Requirements for underground labor.
49.24.100 - Lighting appliances.
49.24.130 - Air chambers—Hanging walks.
49.24.150 - Explosives and detonators.
49.24.160 - Air plant—Feed water.
49.24.170 - Electric power requirements.
49.24.190 - Cars, cages, buckets—Employees riding or walking.
49.24.200 - Speed of vehicles.
49.24.210 - Oil supply restricted.
49.24.220 - Explosives, use of—Blasting.
49.24.230 - Firing switch—Warning by blaster.
49.24.240 - Inspection after blast.
49.24.260 - Requirements as to caissons.
49.24.270 - Shields to be provided.
49.24.280 - Caissons to be braced.
49.24.290 - Cages—Hoisting apparatus.
49.24.300 - Buckets in vertical shafts.
49.24.310 - Telephone system for tunnels.
49.24.320 - Location of lights.
49.24.330 - Generators, transformers, etc., to be grounded.
49.24.340 - Electrical voltage.
49.24.350 - Lamps to be held in reserve.
49.24.360 - Insulators required.