263. A signal system allowing communication between the hoistroom and any shaft station or level where the conveyances can stop shall be installed for each hoisting compartment. Signals issued by means of such a system shall comply with the signal codes prescribed in sections 269 and 277 and shall be different:(1) from the other ambient signals;
(2) from one hoist to another, where there is more than one hoist the shaft.
During inspections or shaft maintenance work, a radiotelephone communication system may be used where:(1) the provisions of sections 264 to 280 are complied with;
(2) the system operates throughout the shaft;
(3) a signal device linked to the system provided for in the first paragraph is available to workers in the shaft.