57 of 124  Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 08: Electrical Works  Cable trays, ladders and trunking shall generally comply with IEC 60364 and shall be constructed from mild  steel sheet hot-dipped galvanised perforated, and of such a design that it is rigid in construction. The choice of  manufacturer is to ensure that bends, tees, intersections, reducers, risers, and droppers are included as standard  in the product range.  Cable trays will be hot dip galvanize and heavy-duty type.  Cable trays, ladders and trunkings shall be sized and provided with isolating barriers in accordance with the  spacing and segregation requirements of cables as mentioned above.  Connection from cable trays will be made with suitable glands.  Where the cable trays, ladders and trunkings are cut, drilled or where the galvanising is damaged in any way the  surfaces shall be adequately treated to restore them to the original galvanised standard. Earthing will be applied to cable trays, ladders and spares.  All cables will be fixed by clamps (brackets) or crochets or plastic bands along the path that they are installed.  In cases where power and control cables are laid together; a cable pan will be placed in between power and  control cables and cables will be separated with this separator.  Supports shall be provided at intervals to assure that the maximum deflection allowed by the manufacturer for  the given loading is not achieved. The weight and quantity of cables placed in cable tray or ladder must not  exceed the manufacturer's recommendations. On selected cable trays, ladders and trunking sufficient space must  be left for additional cables necessary for the future plant extension. The number of cables installed shall be  limited ensuring the resulting space factor will not exceed 45%.  All vertical cable trays, ladders and trunking must be provided with perforated covers of equal treatment fixed  in place by means of bolts until 2 m above floor level.  8.16.3 Conduit systems  8.16.4 Cables in ground  Conduits within buildings and structures shall be either super-high impact heavy gauge PVC conduit, installed  with solvent welded joints, or shall be manufactured from galvanised steel and shall be installed with screwed  fittings. Conduits installed external to buildings shall be galvanised steel. Where galvanized steel conduit is cut  or where the galvanization is damaged in any way the surfaces shall be adequately treated to restore it to the  original standard.  Fittings and accessories associated with conduit systems shall be either manufactured from non-corrodible  materials or suitably coated to render them non-corrodible. No conduit shall be smaller than 20 mm diameter.  Pull-boxes shall be spaced so that there is not more than two solid bends, or their equivalent, or more than nine  metres of straight run between pull-boxes.  All main race trays in ground shall be constructed as channels of concrete in the ground. At the walls of the  channel 2 or 3 cable trays shall be installed at each side. The channel shall be covered by concrete slabs. The  installations are to ensure cables maintain required segregation by providing at least one cable tray for each type  of cable (signal cables, power cables).  In routes with fewer than 10 cables, cables can be installed in pipes, one pipe for each type of cable. Generally  pipes will be 100 mm diameter and in any event sized so that only half of their capacity is taken up by cables.  Conduits are to extend beyond road edges by 500 mm. For the maximum length of every 50 meters the pipes  must be connected to a manhole in order to ease installation of new cables.  TECHNICAL GALLERY AND TECHNICAL CANALS  8_Vol3_d4 3_Section 8 electrical works_en_GIR rev6.doc 