51. Provisions applicable to medium, high or extra-high voltage installations .-The following provisions shall be observed where energy at medium, high or extra-high voltage is supplied, converted, transformed or used:
(1)(a)All conductors (other than those of overhead lines) shall be completely enclosed in mechanically strong metal casing or metallic covering which is electrically and mechanically continuous and adequately protected against mechanical damage unless the said conductors are accessible only to an authorised person or are installed and protected to the satisfaction of the Inspector so as to prevent danger:[Provided that non-metallic conduits conforming to the relevant Indian Standard Specifications may be used for medium voltage installations, subject to such conditions as the Inspector or Officer appointed to assist an Inspector may think fit to impose.](b)[ All metal works, enclosing, supporting or associated with the installation, other than that designed to serve as a conductor shall be connected with an earthing system as per standards laid down in the Indian Standards in this regard and also in accordance with rule 61 (4).] [ Substituted by G.S.R. 358, dated 30.4.1987 (w.e.f. 9.5.1987).](c)Every [*] [ The word " main" omitted by G.S.R. 170, dated 15.1.1979 (w.e.f. 3.2.1979).]switchboard shall comply with the following provisions, namely:-(i)a clear space of not less than 1 metre in width shall be provided in front of the switchboard;(ii)if there are any attachments or bare connections at the back of the switchboard, the space (if any) behind the switchboard shall be either less than 20 centimetres or more than 75 centimetres in width, measured from the farthest outstanding part of any attachment or conductor;(iii)if the space behind the switchboard exceeds 75 centimetres in width, there shall be a passage-way from either end of the switchboard clear to a height of 1.8 metres.(d)[ In case of installations provided in premises where inflammable materials including gases and/or chemicals are produced, handled or stored, the electrical installations, equipment and apparatus shall comply with the requirements of flame proof, dust tight, totally enclosed or any other suitable type of electrical fittings depending upon the hazardous zones as per the relevant Indian Standard Specifications.] [ Inserted by G.S.R. 529, dated 1.7.1986 (w.e.f. 19.7.1986).](2)[ Where an application has been made to a supplier for supply of energy to any installation, he shall not commence the supply or where the supply has been discontinued for a period of one year and above, recommence the supply unless he is satisfied that the consumer has complied with, in all respects, the conditions of supply set out in sub-rule (1) of this rule, rules 50, 63 and 64.] [ Substituted by G.S.R. 256, dated 28.2.1983 (w.e.f. 26.3.1983).](3)Where a supplier proposes to supply or use energy at a medium voltage or to re-commence supply after it has been discontinued for a period of six months, he shall, before connecting or re-connecting the supply, give notice in writing of such intention to the Inspector [or any officer of specified rank and class appointed to assist the Inspector] [ Inserted by G.S.R. 466, dated 18.7.1991 (w.e.f. 17.8.1991).].(4)[ If at any time after connecting the supply, the supplier is satisfied that any provision of the sub-rule (1) of this rule or of rules 50 and 64, is not being observed he shall give notice of the same in writing to the consumer and the Inspector, specifying how the provisions has not been observed and to rectify such defects in a reasonable time and if the consumer fails to rectify such defects pointed out, he may discontinue the supply after giving the consumer a reasonable opportunity of being heard and recording reasons in writing, unless the Inspector directs otherwise. The supply shall be discontinued only on written orders of an officer duly notified by the supplier in this behalf. The supply shall be restored with all possible speed after such defects are rectified by the consumer to the satisfaction of the supplier.] [ Substituted by G.S.R. 732, dated 18.6.1985 (w.e.f. 3.8.1985).]
