Section 128(17) in The Coal Mines Regulations, 2011
(17)Where roof bolts are used for support,(a)only full column grouted roof bolts with adequate bearing plates shall be used,(b)holes shall be drilled to correct diameter and length with a suitable drill maintaining verticality/ correct inclination in accordance to the support plan,(c)hole diameter shall not be more than 8 to 12 mm larger than the bolt diameter,(d)roof bolts shall be installed as soon as the roof has been exposed, under the direct supervision of an assistant manager or overman or mining sirdar.
