Wall lights blowing bulbs

[down2earth]

Hi all,

I have a theory that I want to put to the test, a customer/chum has some wall lights in the lounge, been there for years no problem, now however one side blows a bulb within 10 minutes of the lights being turned on, I have checked the wiring as far as possible and it all seems to be OK, but, interestingly this started happening shortly after they had cavity wall insulation put in, and, co-incidentally, there is a line of holes on the outside wall that pretty much corresponds to where the wire would be running, so putting 2 and 2 together my suspicion is that they have 'nicked' the wire going to the wall light. I would be grateful if anyone has any other ideas. I'm assuming that all I can do is try and pull a new wire through when I take out the old one.

For info I am Part P qualified but not rich in experience as you can probably tell.

Thanks for any help

Down2earth.

 

[ezzzekiel]

have you done an ir test

 

[mikey12]

Hi down2earth sounds suspect to me did continuity and resistance check out ok ?Sounds strange though would have thought you would have problems with both but then it could as you say cable could probably been caught between lights im sure someone else will be along with some more ideas

Hi down2earth sounds suspect to me did continuity and resistance check out ok ?Sounds strange though would have thought you would have problems with both but then it could as you say cable could probably been caught between lights im sure someone else will be along with some more ideas

oh beat me too it

 

[Deleted member 9648]

In my experience you can usually put this sort of thing down to rubbish lamps rather than a wiring fault but it does seem odd if it is consistently blowing. Is there any flickering on that lamp that might indicate a poor lampholder contact?

 

[spadxiii1918]

Heating effect in the cables as the lights are turned on, cable warms up, causing short? Just a theory. More like wirepullers theory though, cheap bulbs

 

[electric-ian]

Hi down2earth - First thing I'd check is lampholder contacts + cont & IR if you think there may be cable damage..

Are you sure the cables are in the cavity? I would expect that wall lights would normally be chased in.

If you have cavity run cabling you may need to do some calculations on the circuits as the insulation could de-rate the current carrying capacity of the cables by 0.5.....

 

[mechelec]

have you done an ir test

I am interested to know how a low insulation resistance reading can blow a bulb????? dodgy bulbs or high volts yes but high volts would affect both sides. I am presuming the OP did mean the lamp and not the associated MCB or RCD???