Another electrical question

[daveyrach]

I have a problem with my upstairs lights in as much as one light in particular trips the rest, I replaced the switch because it was faulty, and checked the pendant and junction box in loft but both show no signs of damage.

I can't check the wiring from the junction box to pendant as we have recently had insulation fitted and i paid someone the relay my loft boards so it is hidden, I suspect the wire has been trapped between the boards or damaged in some way so i was just going to run a new cable from the pendant to the junction box.

Anyone know what else it could be as the other 5 lights on the circuit work with no problems.

[NTECUK]

So it only trips out when you switch that lamp on ?
Bulb or wire to switch

[daveyrach]

Yes just that light, I checked cable from switch as it is only 6 feet long and goes up inside stud wall straight into junction box in roof. The wire from said junction box the light is hidden but I suspect this to be damaged when the guy boarded the loft. I may change both cables.

Also tried a bulb from another light still trips it out.

[monkey]

If you have a multimeter you can test the cable easily enough so you don't have to replace them both. It does sound like a screw through a cable to me.

[daveyrach]

Cool I do have a multimeter I was planning on testing them when I get in from work, the light is in my 2 year old daughters room and she was just going to bed when I realised there was a problem so couldn't test it.

[daveyrach]

Sorted, was the cable from the pendant, replaced the pendant aswell just to be sure. The cable was trapped between 2 boards and the insulation broken, live was touching earth hence why it tripped when switched on.