Strange Fault

[securespark]

Customer call today. Intermittent loss of power.

Discover this has only happened since an RCD incomer was installed 3 months ago.

Customer complains of RCD tripping when slamming door downstairs, turning light on upstairs or going into the study. It was discovered that each activity vibrated the landing floor.

A few board-lifts later....

The cable with sheath stripped back. Somehow the nail managed to damage the insulation to both live conductors. The cpc was "welded" to the line conductor having shorted and melted the pvc.

 

[sparky0000]

the landing light has prob got a borrowed neutral off the other lighting circuit, im taking it is a dual rcd, i would do some ir tests on the circuits, first

 

[electronicsuk]

the landing light has prob got a borrowed neutral off the other lighting circuit, im taking it is a dual rcd, i would do some ir tests on the circuits, first

My guess would be nail through line/neutral down to CPC under the landing floor, but we'll await securesparks confirmation. I hope there's a prize!

 

[securespark]

Did the pictures not come up then?

There is only one RCD incomer. The damage is a nail through a leg of the ring.

I have IR'd the whole install and it's clear having repaired that SC.

 

[Chri5]

Customer call today. Intermittent loss of power.

So the contact can't have welded together until very recently ?

 

[securespark]

No. Today.

 

[Chri5]

So for months the virbration simply moved the wires close enough to contact and trip the rcd.

Then when reset the virbration had stopped, so the fault was clear

Odds on that happening ?