9.6 CABLE TRUNKINGS
Cable trunkings shall comply with IEC 61084. They shall be fabricated from galvanised sheet steel and finished with two coats of standard orange enamel. They shall be equipped with removable covers at suitable intervals. They shall be supplied in lengths to suit the installation and shall have the following minimum wall thickness: –
NOMINAL SIZE MINIMUMWALL THICKNESS
(mm x mm) (mm)
50 x 50 and below—————————— –1.0
75 x 50 to 100 x 100 —————————–1.2
150 x 50 to 300 x 150 ————————– -1.6
Above 300 x 150——————————— 2.0
All trunking elbows, offset and combination elbows, adaptors and tees shall be of same thickness as the straight trunking and shall be the type manufactured and supplied by the same trunking manufacturer. The trunking shall be supported by fixing brackets so that the trunking will not be in contact with the walls or floor slabs. The brackets shall be installed at intervals not greater than 1500 mm for vertical runs and not greater than 1000
mm for horizontal runs. The brackets shall be derusted, finished in a primer and coated with standard orange enamel.
Wherever the trunking passes through a floor or a fire resistant wall, fireresisting barrier shall be provided. At these positions the cables shall be sealed with non-hygroscopic fire resisting material of minimum 2-hour fire rating and approved by Jabatan Bomba Dan Penyelamat Malaysia. In addition, the floor openings and wall openings shall be sealed with similar type of compound. Cables running in the trunking shall carry conductor identification colours and shall be supported by split hard wood racks securely fixed at the base of the trunking and spaced not more than 600 mm apart.
Cables for each final circuit shall be properly bunched together and labelled. Where conduit is tapped off from the trunking, suitable brass type smoothbore bushes shall be fitted at all conduit termination. Unless otherwise specified, all trunkings shall have either tinned copper tape of dimension not less than 25 mm x 3 mm as circuit protective conductor or earth cable of appropriate size. In the later case, all trunking joints shall be bridged by means of tinned copper tape of dimension not less than 25 mm x 3 mm