lighting problem

[llywelyn111]

hi,

I got called out to a flat Friday were one room lights wouldn't work, and one lighting circuit trips the MCB about 3 times every day.

First problem was a straight forward neutral of the flex come out of the pendent while removing shades I presume. The next problem has me stumped.

When the kitchen and living room lights are on for about 2-5 hours it trips the MCB. The living room has 2 pendents and the kitchen has 3 50w GU10 spot lights, so it only has 350W. I have IR tested the circuit and Live -Neutral is 25Mohms Live-earth 299Mohms, Earth-Neutral 195Mohms. Checked IR with Switches on and off to check switch wires.

It never trips when you turn the lights on, just after about 2-5 hours. There are 3 amp sockets in the living room but nothing is plugged in as they haven't moved in yet, they are currently just painting the place.

These 3amp sockets were added after by the looks of it. It doesn't trip when they walk in a certain place, as I was thinking cable been trapped under floor board or nail going through when they stand on the floor board.

Any other suggestions on what it could be?

 

[dingledong]

sounds like the breaker possibly

 

[Specialist]

Take out the 3 GU10's & just leave the living room pendants run, can't remember where it was but I read an article recently about this happening with some GU10's when hot. Try a Google search for GU10 & you may find it.

 

[llywelyn111]

sounds like the breaker possibly

I swapped the lighting circuits around in the board, been caught out with that one before.

 

[llywelyn111]

Take out the 3 GU10's & just leave the living room pendants run, can't remember where it was but I read an article recently about this happening with some GU10's when hot. Try a Google search for GU10 & you may find it.

The fittings do look like B&Q value range so I'll try that

 

[dingledong]

sorry:frown:

 

[GLENNSPARK]

Replace MCB....see if the problem persists......

 

[GLENNSPARK]

i`v just done it n all...lol...:81:

 

[GLENNSPARK]

Try IR at 1000V....see if theres a breakdown....dont worry, you wont damage the cable/s.....sometimes problems manefest themselves when under higher tensions.....

 

[llywelyn111]

Try IR at 1000V....see if theres a breakdown....dont worry, you wont damage the cable/s.....sometimes problems manefest themselves when under higher tensions.....

I'll give that a try. It does look like some DIY wiring has been going on too. Tomorrow could be a long day

 

[GLENNSPARK]

Well i would always ask the question "had or done any work recently here".....if so..should be your first place to go to........save loads of time that can.....

 

[Richard Burns]

I would be visually checking the wiring on the GU10 fittings to see if there is something live touching the fitting when the light gets hot, are the cables burnt, etc.

Try clamping the lighting supply and see if you are running a high current then switch lights off disconnect lamps until the current drops to track the problem. 3-5 hours would likely be about 8 amp draw, which does seem unlikely with your IR readings.