Section 153(7) in The Coal Mines Regulations, 2011
(7)The height or width of any working referred to in sub-regulation (3) or sub-regulation (6) shall not exceed 2.4 metres and there shall be maintained at least one bore-hole near the centre of the working face, and sufficient flank bore-holes on each side; and where necessary, bore-holes above and below the working at intervals of not more than five metres.
