The signal system shall consist of a tube, or tubes, or wire encased in wood or iron pipes, through which signals shall be communicated by electricity, compressed air or other pneumatic devices or by ringing a bell. When compressed air or other pneumatic devices are used for signaling, provision must be made to prevent signal from repeating or reversing.
225 ILCS 705/7.12
At every mine where men are hoisted and lowered by machinery there shall be provided means of signaling to and from the bottom man, the top man and the engineer
Laws 1953, p. 701.
Official source: Illinois General Assembly. Reproduced from public-domain Illinois statutes; confirm against the official source for the current text. Not legal advice.