DIY: new light fitting or wiring faulty?

[Peter Griffin]

I am trying to replace a ceiling rose with a new chandelier. I had all the wiring carefully complete, turned the power back on and...trip! Tried a couple of times and no joy.

The wiring looked correct. I think it is the unit. The company I bought it from want to collect it and then test it before sending out a replacement. Bit of a hassle. So wanted advice on whether it could be the wiring rather than unit...

I can send photos of the wiring but the big give away to me is that when I replace the old fitting it works fine. No tripping.

2 photos...
1 of the unit I'm trying to fit.
1 close up of the wiring, with the original fitting in it. That works fine

 

[westward10]

It 'looks' correct however you have not earthed the new fitting. A couple of possibilities it is wired incorrectly, difficult to judge from your pics as no idea what is behind the hook plate second you may have screwed through one of the cables.

 

[Peter Griffin]

Thanks for the response! Appreciate it.

So the picture I have sent is of the old fitting. It doesn't have an earth. And that one is working fine.

When I replace it with the chandelier...i.e. the blue where the blue is, the brown where the black is, and wiring in the two earths...that is when it trips.

 

[westward10]

I'm with you now so you have put the old fitting back up and all is fine?
Have you put up another hook plate.

 

[Peter Griffin]

Yeah bang on. All is fine when I put the original fitting back on.

 

[westward10]

It would be unusual but from what you say the new fitting must be at fault.

 

[mike jones]

I am trying to replace a ceiling rose with a new chandelier. I had all the wiring carefully complete, turned the power back on and...trip! Tried a couple of times and no joy.

The wiring looked correct. I think it is the unit. The company I bought it from want to collect it and then test it before sending out a replacement. Bit of a hassle. So wanted advice on whether it could be the wiring rather than unit...

I can send photos of the wiring but the big give away to me is that when I replace the old fitting it works fine. No tripping.

2 photos...
1 of the unit I'm trying to fit.
1 close up of the wiring, with the original fitting in it. That works fine

Are you sure you haven’t screwed into the wires when you fixed the hanging bracket?

 

[Peter Griffin]

Pretty sure yeah... Since the original fitting works fine when I put it back on. Wouldn't that also trip if I'd screwed into the wires?

 

[mike jones]

Pretty sure yeah... Since the original fitting works fine when I put it back on. Wouldn't that also trip if I'd screwed into the wires?

Have you done insulation resistance test on the new light fittings?

 

[Peter Griffin]

Have you done insulation resistance test on the new light fittings?

I haven't, no. Not sure I know what that is. I have a multimeter at home, is that what I need?

 

[westward10]

I haven't, no. Not sure I know what that is. I have a multimeter at home, is that what I need?

If your old fitting works then all evidence suggests the new fitting must be at fault.

 

[Avo Mk8]

Pretty sure yeah... Since the original fitting works fine when I put it back on. Wouldn't that also trip if I'd screwed into the wires?

If the earthing arrangement of each lamp is different, it's vaguely possible that one might trip and the other not, if there's leakage to the metal ceiling plate, e.g. trapped a wire as has been suggested.

For example, your old fitting has 3 core flex, and the earth in that goes to the bulbholder, but is probably not connected to the other metalwork. Did you connect the separate earth wire on the rose to the Wago earth as well, when you put the original light back?

If not, I think it would be worth strapping a wire from the earth Wago onto the ceiling plate, just to make sure that doesn't cause a trip. Don't need the light connected up, just earth the plate and turn it on!

 

[littlespark]

It looks to me like this is a loop in system. I think I see browns in the centre hidden by the hook.
Perhaps one of these has exposed copper touching the hook plate…. But then, the hook plate would need to be earthed to cause a problem.

The cables passing through holes in the hook plate doesn’t look right to me…. If designed that way, they should have rubber grommets protecting the cable.
And cables passing through separate holes…. I don’t think eddy currents will be a problem here


To test your new fitting… you could test using your multimeter on the mega ohms scale Between Live and Earth, and between neutral and earth… both should be very high readings, indicating an open circuit. (Very low would suggest a short between these)

Testing between live and neutral would be inconclusive as there may be lamps in between.
LEDs or transformers within the fitting can give strange results.

You could also temporarily wire a plug to the new fitting flex, and plug it into a socket to test…. Although you risk tripping the socket circuit doing it this way if there is a fault.

 

[Spoon]

You could also temporarily wire a plug to the new fitting flex, and plug it into a socket to test…. Although you risk tripping the socket circuit doing it this way if there is a fault.

This is what I has half way through typing before you posted.
Just bung a plug with a 3A fuse in it, on the new light.

 

[Peter Griffin]

Thanks so much for all the suggestions. Just cracked it!...

I tested the plate with a live screwdriver tester. It lit up. Removing the screws on a trial and error basis I was able to identify which one was the issue. Sorted!

Great forum this. What a fab response.

 

[littlespark]

Glad you found the problem... what was it? an exposed cable?

Oh, and dont trust those screwdrivers for telling you something is dead... they are notoriously inaccurate sometimes

 

[Avo Mk8]

I was able to identify which one was the issue. Sorted!

Hopefully removing the offending screw was not the only remedy,
but you also sleeved the 'wounded' insulation and moved the wire to safe route?