Proper care and precautions should be taken while handling, storage and installation of Power cables. The general recommendations are as follows.
HANDLING : The cable drums should be unloaded from trucks or railway wagons with the help of crane, fork lift or using a proper ramp with 1:3 or 1:4 incline so as to avoid damage to the outer layer of cables. The cable with drum or without drum should never be thrown or dropped on the ground from the truck or wagon.
The cable drum should always be stored with flanges vertical and not lying flat on the ground.The drum should be rolled in the direction of arrow to avoid loosening and entanglement of cable winding. The drum should not be rolled on rocky uneven surface with sharp projections.
STORAGE : The cable drum should be stored in dry covered area having concrete/firm surface. The drum should be stored in such a way that the bottom end of cable is not damaged. Cable drums should not be stored one above the other.
INSTALLATION : Cable should be unwound from the drum after lifting the drum on the centre shaft supported on both the ends with suitable jacks/ stand. If the cable is in coil form then it should be unwound by putting the coil on a rotating pay off or by rolling the coil held vertically. If unwinding the coil by rolling then it should be ensured that the ground surface is even and smooth so that the cable is not damaged.
Proper care should be taken during laying to avoid sharp bending and twisting.
If the installation is being done in very cold condition then it should be ensured that all the layers of the cable have been warmed upto 4 0C for at least 4 hours before unwinding. This is because PVC becomes hard and brittle at low temperatures and may crack during unwinding.
Recommended safe pulling force in Newtons when cable is pulled with pulling eye is:
a) For Aluminium Conductor Cable 30 x total conductor area in sq.mm.
b) For Copper Conductor Cable 50 x total conductor area in sq.mm
Recommended safe pulling force in Newtons when pulled with stockings is:
a) For Armoured Cable 9 x D Square
b) For Unarmoured Cable 5 x D Square
|Power Cables||1.1 KV Cables||11 KV Cables||33 KV Cables|
|Single Core Cables||15 x D||15 x D||20 x D|
|Multicore Core Cables||12 x D||15 x D||15 x D|
Where D is diameter of cable in mm.