Two lights have stopped working - details inside

[martin645]

Hi,

I am trying to troubleshoot two lights that have recently stopped working. They both stopped working at the same time. One is a ceiling-mounted MR16 bulb, the other is the outside light where the cable emerges near the front door. These two lights are physically close so I suspect that the problems with them might be related.

I have tried replacing both the lights (the MR16 ceiling light with a known-good bulb, the outside light with an entirely new fixture). I have tried resetting all the breakers.

I just used a multimeter to confirm that there is no voltage at the leads coming off the transformer for the MR16 fixture. Question: is it possible that the power supply for the outside light is wired downstream of the transformer, and therefore the broken transformer is preventing power getting to it?

What are the next troubleshooting steps? I want to take a look at the transformer and see if there's anything obviously wrong (presumably it might just be a dodgy connection from the mains), but I can't see how to do it short of cutting a hole in my ceiling. Is there anything else I should try first?

If any further details or pictures would be helpful, please say and I will supply them!

Cheers,
Martin

 

[PrenticeBoyofDerry]

Is the outside fitting using a 12V lamp?
Have you checked if the supply primary side of the transformer has voltage?
I suspect it could be a transformer fault!
It would be helpful if you had the details of the spec of the transformer.

 

[martin645]

Is the outside fitting using a 12V lamp?
Have you checked if the supply primary side of the transformer has voltage?
I suspect it could be a transformer fault!
It would be helpful if you had the details of the spec of the transformer.

Thanks for the quick reply!

No, the outside fitting is 240V.

My plan is to check the voltage to the supply side of the transformer as you say, but the transformer is in the ceiling and there's no obvious way to get at it without cutting a hole, which might be a bit of a job. I find myself wondering how it was put up in the first place!

If I end up chopping up the ceiling to get at the transformer, I'll update this thread with specs.

 

[PrenticeBoyofDerry]

Well that is one reason to gain access to the transformer, as it should be easily accessible. Are you sure it will not come through any hole made for the ceiling light? Is this a recessed downlight? as often there is ample room for them to come through the hole cut.
If the outside light is not 12V, it should not be on this transformer.

 

[martin645]

Well that is one reason to gain access to the transformer, as it should be easily accessible. Are you sure it will not come through any hole made for the ceiling light? Is this a recessed downlight? as often there is ample room for them to come through the hole cut.
If the outside light is not 12V, it should not be on this transformer.

Yes, it's a recessed downlight.

I will have another root around - it felt like the transformer was too big to come down through the hole for the fitting, but maybe if I remove the bit that surround the bulb, it might fit.

Thanks for the advice,
M

 

[PrenticeBoyofDerry]

They often do pull through, but as you have said, you may have to remove the complete fitting from the hole.
Before you attempt this, do isolate the circuit and any other circuit that could be possibly up there, don't want you getting a tickle!

 

[martin645]

They often do pull through, but as you have said, you may have to remove the complete fitting from the hole.
Before you attempt this, do isolate the circuit and any other circuit that could be possibly up there, don't want you getting a tickle!

Don't worry - I have a "all breakers off" policy when it comes to sticking my fingers into wires that I can't see!

 

[PrenticeBoyofDerry]

Don't worry - I have a "all breakers off" policy when it comes to sticking my fingers into wires that I can't see!

Untitled

• PrenticeBoyofDerry
• 31 Aug 2013
• 3

 

[martin645]

Well, the primary side of the transformer is fine, so it must be the transformer that's the problem. It's definitely too big to come out of the hole though - think I'm just going to cut it off and wire in a normal boring old pendant fixture.

 

[PrenticeBoyofDerry]

Well, the primary side of the transformer is fine, so it must be the transformer that's the problem. It's definitely too big to come out of the hole though - think I'm just going to cut it off and wire in a normal boring old pendant fixture.

Or remove trany and convert to 230V GU10 lampholder

 

[martin645]

Now that's an interesting idea... I have a bunch of LED GU10 bulbs spare so I could use one of them. Thanks for the suggestion, I will order one now!

 

[martin645]

Hope you don't mind me jumping in with another question....

I got a couple of GU10 lampholders in the mail today and I'm trying to figure out whether I have to wire them to ground or not. They have a three-pole connector but the plastic casing looks like it's designed to have only two cables entering:

Thoughts?

 

[riveralt]

I got a couple of GU10 lampholders in the mail today and I'm trying to figure out whether I have to wire them to ground or not. They have a three-pole connector but the plastic casing looks like it's designed to have only two cables entering:

That would be earth not ground.
These lights require an earth connection.
It is important that you follow the manufacturers instructions.

 

[bernardgreen]

They have a three-pole connector but the plastic casing looks like it's designed to have only two cables entering:

Each cable can have Live Neutral and EARTH conductors inside the cable.

The problem you have is that cable clamp apears to be designed for round cable and may not perform well with oval shaped twin and earth.

 

[martin645]

Ah, I think I understand - the two cable holes in the casing are designed so that you can have a LNE cable going in AND coming out - Doh!