Section 84(7)(b) in The Coal Mines Regulations, 2017
(b)Where the shaft exceeds 45 meters in depth, the persons working at the bottom of the shaft shall also be protected by an adequate protective covering, extending over the whole area of the shaft which shall be provided with a door for the passage of the bucket or other means of conveyance, to be kept lowered to within 22.5 metres of the bottom of the shaft at all times when sinking is in progress: