Light circuit problem

[mctaff]

I've just wired a new ceiling light into the upstairs circuit. Everything worked fine - the other two lights on the circuit - until I turned the new light on. The MCB then tripped and now it won't turn back on, even with the main power to the box switched off.

The wiring into the junction box for the lighting ring is correct (3 reds together, 3 earths together, 2 blacks for the ring together and the black from switch by itself, the new light then connected across the blacks), and the circuit worked fine until I turned the new light on.

The full load of the ring is: one 60w bulb on one dimmer switch, 3 halogens on one dimmer, and the new light (5 x 25w) on one dimmer, so I don't think the circuit should be overloaded.

Any ideas? Has the MCB broken? Dimmer broken?

Unforutnately due to the prescence of dimmer switches, I can't figure out how to turn all the lights off before I try and switch the MCB back on. Grr.

I have also removed the new light from the circuit, but still no joy.


Any advice very welcome - I'd like some lights on again tonight!!

 

[Steve]

If the MCB wont reset with no power to it, its goosed. You need a new MCB. Though I'd like to know why it tripped.

also, its not a ring.

and does the new fitting have a transformer in it?

 

[Spark123]

If all your wiring is correct then I'd be looking at the possibility of a faulty light fitting. Will have probably blown the dimmer switch too now.

 

[mctaff]

Fitting doesn't appear to have a transformer - it's just an incandescant bulb fitting - unless it's very well hidden in the metal part of the light, which I doubt.

Fitting is ex display and worked fine in the shop before they gave it to us...


How would I best test the fitting in isolation? Can I attach a plug and try it in a socket?

I have a new MCB, so I'm going to stick that in (without the new fitting, so I can have some lights this evening!) and try and figure out if the new fitting has an problem.

 

[Spark123]

If there is a short in the fitting you may be able to find it using a multimeter, however if you know someone who has an insulation tester (aka Megger) that would be better.

 

[mctaff]

Fitted new MCB... rewired new fitting.

All working no problems.

Weird!

 

[Steve]

Just your MCB's time to die perhaps. Let it go quietly and give it a decent burial.