At road crossings, sewerage pipe crossing, water pipe crossings, paved areas, concrete areas, concrete areas and where specified by the S.O.’s Representative cables shall be protected by galvanised steel pipes buried to a depth of 900 mm below finished ground level. The pipes shall be of heavy duty type, complying with BS 1387 and complete with screwed and socketed joints. Unless otherwise specified the pipes shall be 150 mm in diameter. Where it is necessary to cross drains, culverts or similar obstruction, which is too deep for the cables to be buried below, galvanised steel pipes as specified above shall be provided
The pipes shall be supported at each end in a concrete block and shall project through the blocks into the ground at a depth of at least 750 mm. All ducts shall be extended at least 600 mm beyond paved areas, concrete areas, drains, road crossing, pipe crossing etc.
Cable entering a building shall be protected by pitch fibre ducts complying with BS 4108 or heavy duty galvanised steel pipes complying with BS 1387 or uPVC pipes complying with MS 978 and MS 1063 as specified of 150 mm diameter completed with bend pieces, buried to a depth of 900 mm and encased with 75 mm of concrete all round. The ducts shall be installed with a gradient so as to drain away any water in the ducts. All
ducts passing through walls shall be effectively sealed and made watertight. Unless otherwise approved by the S.O.’s Representative, the number of cables installed in each duct shall be such that the space factor shall not exceed 45%. A draw wire shall be provided for each duct.
Unless specified to be provided by others, the above galvanised steel pipes, pitch fibre ducts and/or uPVC pipes shall be provided by the Electrical Contractor whether they are shown in the Drawings or not.