ELV Conundrum...

[Grant Naylor]

A client has 8 ELV down lights in a ceiling in an single story extension on the kitchen, so there is no roof space.

There are 3 switches 1 controlling 2 ELV and the others each 3 ELV lights.

2 ELV circuit works fine
3 ELV circuit 1 - one light still works
3 ELV circuit 2 - no lights working

Main problem - can't access the fixed wiring the lights only pull out enough to allow the transformer to drop out along with the ELV but that's it, no J-Box.

I only had a quick look and not yet tested if any volts after the transformer, but I would assume since some are still working more than likely the transformers have stopped working on the broken lights. Bulbs have apparently been replaced and nothing working.

Not really done much with ELVs but not too optimistic for these.

My only thoughts are:

Confirm bust transformers as expected
Isolate
Snip out the broken transformers on the LV wiring side
Terminate LV wires into connection strip
Voltage test to ensure switch wire is live

If switch wire not live:
Isolate
Chocbox cover over the strip.
Place back in the ceiling space and put the ELV accessory back in place disconnected.

If switch wire live:
Isolate
Terminate new transformers into connection strip
Chocbox cover over the strip
Put back in ceiling
Should be sorted


That sound reasonable? If switch wires turn out to be dead I can't see a way of getting them sorted out without pulling the ceiling down.

However, this sounds like a bit of a minefield in terms of what could be the issue. I only really get to see if the fixed wiring is bust after snipping off the transformer to get to the LV wiring. I don't want to be responsible for having to fix something I can't get...

Any thoughts?

 

[telectrix]

before condemming trannies, check the lamp connectors. black pins on the lamps point to poor, tired connectors. but duff trannies is a distinct possibility. use a volt stick on the LV ( primary ) side to ascertain switched L present without snipping.

 

[KFH]

Use a volt stick rather than disconecting a light as a first step. I would suspect the transformers but it does appear to be a high failure rate. Are the transformers in insulation? It would be normal to fill a roof like that with the stuff.

I would be tempted to use a cable tracer, find where the junction boxes are and take down a small section of ceiling and rewire the lot for LV lights, possibly LEDS. Then make good the ceiling, or get a plasterer to do it for me.

 

[Grant Naylor]

Ahh I'm a bit too snip happy I see, thanks I'll invest in a volt stick... Doh! Never crossed my mind ;-)

 

[Grant Naylor]

Other thought, say the transform is duff and I replace. I still need to locate the JBox to do Zs readings for the MEIWC right? :-(

 

[KFH]

You could do it at the connection box for the transformer if you can reach it. I am assuming from what you have said they have a short length of flex on them moulded in rather (prewired) than the type with the connector in the transformer. If you end up having to snip the cable it may not have an earth in it for testing, some of the prewired transformers are catII, I think. I am having one of those silver blonde moments.

 

[telectrix]

if you can't access the JBs you can't get a Zs. depends on how much demolition the customer will allow.

 

[Grant Naylor]

You could do it at the connection box for the transformer if you can reach it. I am assuming from what you have said they have a short length of flex on them moulded in rather (prewired) than the type with the connector in the transformer. If you end up having to snip the cable it may not have an earth in it for testing, some of the prewired transformers are catII, I think. I am having one of those silver blonde moments.

Yup pre-wired no earth.

 

[ipf]

Seems like they were installed on build before the ceiling was fixed. Obviously no thought of future maintenance. Looks like a pad saw or hole saw job.

 

[Grant Naylor]

if you can't access the JBs you can't get a Zs. depends on how much demolition the customer will allow.

As litte as possible.

So far I think I'll:

Check for insulation as could be an issue anyway even if I did replace ELV's
Try and locate JBox and double check to see if they can be reached at all (thank god for camera phones!).
I think they would like it done as one job so they need another sparky as I can't plaster for toffee