The effect of cable screen one or two sided bounding

Two sided bonding will reduce the induced voltage but increase the circulating current in the cable sheath. This circulating current will cause heating to the cable and reduce its maximum ampere rating. Single point bonding can be done but there may be high induced voltage present on the floating non-earthed end. However, there is a benefit in the fact that there will be no circulating current in the cable which improves the cable's ampere rating.

This is why for long cable circuits, we use cross bonded cable sheaths. We can ensure that there is minimal cable sheath circulating current and induced voltage with this method.

In many applications we use the cable screens as path for earth fault current towards the source, so we need to bind both sides of the cable screen. It is important the current carrying capacity of the cable screen equal or greater than the earth fault current of the system. To prevent nuisance tripping due to equalizing currents the cable shield must loop out the core balance CT.

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