735 قنوات الكابلات

735 CABLE TRUNKING

735-1 Cable trunking may be employed for housing single core cables at special locations where it is diffic ult
to install conduits. They may be of metallic or non -metallic construction. Non-metallic cable trunking shall be
constructed from non-combustible insulating material like polyvinyl-chloride which shall be fully suitable for
use in the climatic conditions and shall comply with the requirements of Clause 725. Metallic cable trunking
shall be adequately protected against corrosion by galvanizing or shall be made of corrosion resistant material or
stove enameled. All cable trunking shall be provided with removable covers.

735-2 Cable trunking shall generally be run exposed and the trunki ng shall be completely erected before
drawing in the cables. Where adequate means of access is readily available throughout its length, cable trunking
may be concealed.

735-3 Every entry to trunking shall be so placed as to prevent the ingress of water and all dead ends shall b e
closed. Only unbroken lengths of trunking shall be employed for crossing partitions and walls.


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735-4 Where a common cable trunking is employed for housing both power and communication circuits, or for
housing circuits operating at different voltages, the trunking shall be provided with separate compartments for
the different types of circuits.

735-5 Cable trunking shall be manufactured from substantial sections to provide adequate strength and rigidity.
All sharp edges, burrs and other projections shall be removed and the trunking finished smooth to prevent injury
to cables.

735-6 All bends, tees and other accessories of cable trunking shall be of substantial sections and of the same
quality as the trunking itself.

735-7 Cable trunking shall be securely supported every metre, when run exposed.

735-8 The number of single core cables that may be housed in a trunking shall be such that a space factor of 45
percent is not exceeded or shall be selected in accordance with the method detailed in Section 15.

NOTE- Where a number of cables are bunched in a trunking the current carrying capacity of the cables shall
be reduced by using the stipulated grouping factor, for full details, refer to Section 15.

735-9 Metallic trunking need not be provided with a separate insulated earth wire and the trunking itself may
be considered as the earthing system provided all joints shall be made mechanically and electrically continuous.
The different sections of the trunking shall be bonded by copper links.

735-10 Non-metallic trunking shall be provided with an insulated earth wire for each circuit.