§ 33.221. Cavern outlets.

 (a)  Only one opening shall be required for ingress and egress if the walls of the shaft are smooth and unbroken, or if the shaft is lined with suitable material so as to leave smooth walls. The cage, bucket or other means of egress shall, at all times, be available for employes.

 (b)  In caverns having only one shaft, an auxiliary standby gasoline or diesel-powered hoist shall be installed and kept in operating condition. This hoist shall be used only to remove men in the event of an accident which deranges the hoisting machinery at the main outlet.

 (c)  Each opening or outlet, escapement, shaft or slope shall be kept free from steam, dangerous gases, standing water, ice and all other obstructions.