Spotlights Tripping Fuse

[lukegeorge]

Hi,

I recently had a leak from an upstairs shower which caused the spotlights in the kitchen below to trip the circuit breaker.

The leak has now been fixed and its been at least 4 weeks of drying out but its still tripping the fuse. However it doesn't always trip the fuse straight away. Sometimes the lights will be on for 5-10 minutes before it trips, other times it trips straight away. Doesn't appear to be any sort of pattern to it.

I've pulled down all the spotlights and the transformers (each light has its own transformer) to visually inspect them for any damage but there appears to be none. Today I removed the transformers one by one however even with them all removed it still tripped the power. They are all connected in a daisy chain fashion with one getting the live feed then a junction box sends that to the transformer and on to the next spotlight until it reaches the end one, 4 in total.

Does anyone have any ideas what might be causing the problem?

 

[EFLImpudence]

Is it an RCD (RCCB or RCBO) that is tripping?

If you are not sure, these will have a test button.

 

[lukegeorge]

sometimes its the lighting circuit and sometimes its the RCD.

 

[EFLImpudence]

Is there something else that may have got wet.

That is, not the light causing the problem.

 

[RF Lighting]

It's possible that the water has allowed rust or carbon tracking to form in a joint which got wet, and is still providing a fault path, despite the joint having dried out.

You need to find the joint and clean / replace it.

 

[lukegeorge]

Is there something else that may have got wet.

That is, not the light causing the problem.

I don't think so. There is damp marks on the ceiling where the leak was and they end well before the end of the lighting circuit. Also nothing else in the house trips even though all the circuits are on. It's only switching the kitchen lights on that does it.

 

[lukegeorge]

It's possible that the water has allowed rust or carbon tracking to form in a joint which got wet, and is still providing a fault path, despite the joint having dried out.

You need to find the joint and clean / replace it.

By joints do you mean the circular junction boxes that connect the wires? I've checked the 4 of them that are connected to the spotlights and they are all clean and dry.

 

[JohnD]

might have run down into the switch

or there could be a joint you have not found

 

[deadshort]

Hi, it could be the light fitting its self thats causing the issue,
I would disconnect it and see if the circuit still trips the breaker.

Regards,

DS

 

[lukegeorge]

might have run down into the switch

or there could be a joint you have not found

Just checked the switch and it isn't that.

I'm thinking there must be a join I haven't found yet. Problem is how do I find it? I've had my camera in the holes for the 4 spotlights and took pictures in all directions using the flash and can't see any more joins.

Is there a nifty trick to finding them or is it a ceiling down/floorboards up job?

 

[planenut]

How about wiring the fitting to a 13amp plug and try that in a socket?

 

[333rocky333]

Hi, it could be the light fitting its self thats causing the issue,
I would disconnect it and see if the circuit still trips the breaker.

Regards,

DS

Unlikely on a 12 volt fitting

Isolate the circuit, Disconnect all 4 transformers and with the Lightswitch off continuity check the wires between the 5 points to locate a potential fault/joint

 

[lukegeorge]

Hi, it could be the light fitting its self thats causing the issue,
I would disconnect it and see if the circuit still trips the breaker.

Regards,

DS

Unlikely on a 12 volt fitting

Isolate the circuit, Disconnect all 4 transformers and with the Lightswitch off continuity check the wires between the 5 points to locate a potential fault/joint

I've isolated the circuit and disconnected all the transformers. When I switch on the light with all transformers disconnected it still trips the electric. How do I continuity check?

 

[deadshort]

Sorry, that's what i meant when i said light fitting. If your light switch has just got two wires +earth , you will have a join box above the ceiling which will be first inline.

Regards,

DS

 

[333rocky333]

In absence of an insulation tester, using a multimeter, then with the circuit off off and the light switch off. and the 4 trans disconnected
Use a multimeter set on continuity and take readings between all combinations of L N and E

You should have a high resistance all ways.
Any low reading would suggest a problem, then you can break the wiring down to sections to find the faulty area.