339. During shaft sinking work, the conveyance used for the transport of persons to the site where blasting took place shall be immobilized 25 m (82.0 ft) above the site of the blasting.
From this level, a descent of such a conveyance may be made only following signals sent from the conveyance and at a speed not exceeding 2 m per second (380 ft per minute).
After blasting, only those persons required for examining the shaft may be transported in the conveyance.