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What precaution should be taken while taken a cable through trenches in the following locations (a) Road crossing, (b) Railway crossing & (c) Crossing of water mains ?

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(a) Road crossing – steel or spun reinforced concrete pipes should be used to carry the cable at minimum depth of 1.00 metre because of their high resistance to mechanical damage from traffic vibrations. The pipe should cross the road on the skew to reduce the angle of bend as the cable enters and leaves the road crossing.

(b) Railway crossing – The cables should be laid under railway tracks in reinforced spun concrete or steel pipes placed at right angles to the track and at such depth as may be specified by the railway authorities but not less than 1 metre measured from the bottom of sleepers to the top of the pipe and the pipe should extend to a minimum distance of 3 metres from the centre of the outer most track on either side.

(c) Crossing of water mains – A minimum clearance of 0.3 metre should be given between the power cable and water mains.

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