(4)Where the shaft exceeds 150 meters in depth ,-(a)the bucket or other means of conveyance, when used for lowering or raising persons, shall be provided with sufficient cover overhead for protection from things falling down the shaft; and(b)there shall be provided for each bucket or other means of conveyance, a sufficient number of guides which shall be kept extended to within 22.5 metres of the shaft bottom at all times when sinking is in progress:Provided that the Regional Inspector may, by an order in writing, require the guides to be provided in a shaft less than 150 meters in depth.
