intermitent fault upstairs lighting circuit

[ianphilip007]

went to a call today, upstairs lighting fault. customer saying that her upstairs lights just stop working, then just start working again. She stated that sometimes it can be 2 days or even a week before they start working again.

at time of visit all upstairs lights worked and switched as they should. all lights remained on together or when switched randomly. IR testing showed no deteriation in insulation for the upstairs circuits. I retightened all connections at board including busbar and checked operation of the MCB. No obvious loose connections were found at the board on this initial visit.

im thinking that this can only be a loose connection that would cause this type of fault. a wavering neutral or live that is losing contact and breaking the circuit, either at the board or the first upstairs rose,as all lights are lost upstairs. She was un clear as to weather the MCB was tripping but the fact that the upstairs circuit appears to go dead for up to a week and then comes back on its own leaves me thinking the above

anyone with other ideas would be most welcome

 

[telectrix]

check that the busbar is correctly aligned in the terminal in bottom side of MCB. sometimes they can be fitted with the busbar behind the terminal.

 

[ianphilip007]

busbar appeared to be fitted correctly tel, all seemed normal guess your thinking this can only be a loose connection ?

 

[ian.settle1]

Hidden JB somewhere with loose connection

 

[cobrauk]

I have found in the past where some one had wired the live for the faulty switch to the switch wire in another room so unless that rooms switch was on the other room wouldn't work is that possible ?

 

[ianphilip007]

could be must be before the first rose if it is. but another place to look.

 

[ianphilip007]

no dont think so cobra as all lights worked when switched individually either when other lights were on or when they were the only light on. circuit appears to be correct, just intermittently looses power, and then power reappears.

at time of visit all was working as it should.

i could have fixed the problem by retightening connections at board only time will tell, as the fault didnt show while i was there its hard to tell.

 

[GJD]

What type of fittings were they?

I've seen this before and it was a dodgy transformer... lights came and went as they pleased - not sure if that helps!

 

[7029 dave]

is it all wired 3 plate? if so have first rose/fittings off check terms /or could be loose jb somewhere in loft etc.

 

[Hants-Spark]

What is the mains board set up, does the RCD/MCB trip during any of this? Maybe a nailed/trapped cable just catching the live/neutral which when someone stands on the right place right time creates the problem. Saying that I would go for the loose connection in a JB. Good luck

 

[Rampantchilli]

If you do a R1+R2 test at the very last accessory then an rn+R2 at the same point, you would be able to identify if there is a poor joint in a conductor. Then follow a systematic approach to checking all along the conductor tightening as you go.

 

[ackbarthestar]

A dead rat boiling away on a JB in the loft causing it to short the upstairs lighting; it then dries out a bit and the lights come back on; a day later and one of his mates comes along and eats a bit more of him and he starts to leak again on the terminations causing the second rat to boil pooring internal fluids all over the inside of the ceiling and the lights go out. If rat fluid drips out while checking the inside of the ceiling rose then you know what the answer is - lol

Alternatively I'd go with a loose live or neutral conductor being disturbed by something in the loft.