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.
RCW 49.24.310
Telephone system for tunnels.
1941 c 194 s 24; Rem
Official source: Washington State Legislature. Reproduced from public-domain Washington statutes; confirm against the official source for the current text. Not legal advice.