Section 21(e) in The Rajasthan P.W.D. Contractor's Labour Regulations, 1966
(e)When workers are employed in sewers and manholes, which are in use the contractor shall ensure that the Manhole covers opened and are ventilated at least for an hour before the workers are allowed to get into the Manholes and the Manholes so opened shall be cordoned of with suitable railing and provided with warning signals or boards to prevent accident to the public.
