problem with metal light fitting

[Steve]

One of our light fittings has tripped the circuit twice this afternoon. Once it wasn't even switched on (the first time) (the circuit is on a 6A MCB and is on the non-RCD side of the board)

I have posted a picture, and there seems to be 2 scorch marks on the metal plate. However, I cannot, for the life of me, see how anything could be arcing or sparking! I wired the fitting myself about 7 months ago and all the connections are tight and secure, no copper exposed. I have checked the T+E cable and it is flawless, good as new. There is another identical fitting opposite (in a large kitchen) which is fine too.

The faceplate is earthed via that earth strapper and the metal thread fixed to the ceiling. Whats happening????

(FYI, the bulbs are Wilko 40w SES spots, they are fine, and the fitting is Ring, from B&Q)


help!

 

[securespark]

Crafty

How do you know that one is the culprit?

 

[JohnD]

have you by any chance been having bulbs blow? Spotlights are very bad for tripping an MCB with a surge when they blow. Loose connections can contribute.

I presume you have a JB up in that ceiling?

 

[securespark]

Once it wasn't even switched on

Thought about this. It cannot be the fitting if it was not switched on when the mcb tripped. You really need to megger the circ.

there seems to be 2 scorch marks on the metal plate.

Could they have been there from new?

I wired the fitting myself about 7 months ago

You allowed to do that?

(FYI, the bulbs are Wilko 40w SES spots, they are fine, and the fitting is Ring, from B&Q)

Hmmm. Wilko lamps don't have Ballotini fuses in. And Ring are not nick-named "Rong" for nothing.

 

[Steve]

The bulbs are fine, as i said before. The light made a sharp pop when the MCB tripped the second time, and there was an audible pop earlier in the day when it must have tripped the first time and there were no lights on. Couldn't tell you the location of the first pop - i was washing up and facing the window.

None of the bulbs have blown since i fitted the 2 sets of lights 5 months ago.

I replaced 2 old plastic fittings with 3 spots, with these 2 metal fittings with 3 spots. I dont see how this is notifiable, even in a spec.loc.

For the time being, i have removed the 3 lamps from the fitting (circuit has been working fine all day) and will see if my mum wants to pay for a spark to come and test things

And JohnD, i certainly hope you aren't implying that I inspect the junction box. Its UNDER THE BATHROOM FLOOR. Which is lino'd and hardboarded (the house was rewired by a spark 15 years ago - not the same one that did the CU change)