Unless otherwise specified, cable trenches shall be 750 mm deep. The trenches shall be of sufficient width to enable provision of adequate spacing between cables but in any case shall not be less than 450 mm wide. Trenches shall be kept as straight as possible and shall have vertical sides which shall be protected where necessary so as to avoid subsidence and damage. The bottom of the trenches shall be firm and of smooth contour and any other objects likely to damage the cable sheathing shall be removed.
The material excavated from the trenches shall be placed or removed so as to prevent nuisance or damage to adjacent areas or buildings. The trench excavation and filling in shall be so executed that all roads, walls, sewers, drains, pipes, cables, structures etc. shall be reasonably secured against risk of subsidence damage. Provision shall be made, during excavation and until interim restoration has been completed, for reasonable access of persons and vehicles to the areas of buildings adjacent to the trenches.
The Electrical Contractor shall provide pumps and other appliances for the necessary pumping required for the disposal of water so as to prevent any risk of the cables and other materials to be laid in the trenches being detrimentally affected. Where necessary, bailing shall be provided. Where trenches pass from a footway to a roadway or at other position where a change of level is necessary, the bottom of the trench shall rise or fall gradually.