SWA continuity

[RobMax]

A 4-core SWA cable laid to supply power to a garden room is not functioning - on doing a continuity check I have established that only 3 of the cores have end to end continuity but the fourth (yellow) reads as an open circuit.

Will this mean a new cable?

 

[ackbarthestar]

Sorry about the delay in responding to your further queries - was called away.

The cores provided a ring circuit with red (live) and black (neutral) with the return being yellow (live) and blue (neutral) with the armour providing CPC. We moved in a couple of months ago and have not used the garden room - I plugged in a fan and it tripped.

On testing the cores and the armour there is continuity in all but the yellow core. I have tested the IR and that is good although not clear - reading 140 mohms - used a Megger MFT.

My thoughts are to convert to a radial and reduce the protective device from a rating of 32A to 16A.

I recon that its unlikely to be a broken yellow core in the cable but disconnected at one of the terminals somewhere,

Light blue touch paper and stand well back ......... Whoosh