386.1. Every shaft shall be timbered and, during shaft sinking work, the timbering shall be maintained to within 15 m (49.2 ft) of the bottom of the shaft.
However, where a multi-deck work platform is used, a distance of less than(1) 15 m (49.2 ft) shall be maintained between the base of the platform and the bottom of the shaft, when there are workers at the bottom, except for inspection reasons related to blasting;
(2) 50 m (164.0 ft) shall be maintained between the top of the platform and the lower chair.
O.C. 1326-95, s. 73; O.C. 916-2011, s. 6.