Can't find downlight transformer(s) in ceiling void

[peejaybee]

Hi

We recently moved into an old property with 12V halogen downlights fitted in the kitchen ceiling. I purchased larger diameter replacement LED lights and went ahead and removed one of the halogens and cut a larger hole to accept the LED. I put my hand in the the larger hole to remove the transformer and……………..no transformer! I removed the other halogen lights and none of them have a local transformer! I’ve used a mirror on a stick to search around in the ceiling void but no transformer in sight!

The kitchen is quite large and above it are two bedrooms and part of the landing all of which have fitted carpets, grippers, underlay all laid on top of hardboard nailed down on top of the floor boards. I really don’t want to have remove this lot and pull up the floor boards on a wild goose chase looking for the transformer(s) which may not be located there at all.

Incidentally the LEDs require an electronic driver and will not operate on the existing 12Vac.

I’m at a loss what to do. I contacted the previous owner who told me the downlights were fitted by an electrician many years ago. I can’t believe an electrician would be stupid enough to locate the transformer in an inaccessible place, if the transformer goes faulty we would lose the lighting to our kitchen!

I’m just wondering if anyone has any suggestions. Would a cable detector be able to sense into the ceiling void and discriminate between a cable and a transformer? I’m clutching straws now

Thanks

 

[stem]

You may have one central transformer somewhere, or several smaller ones. When 12V halogen spots first came out, a single transformer would sized according to the total load of the installed lamps. A correct, stable supply was important to prevent a reduction in light output, or premature burnout. Some came as kits with one transformer and a wiring harness for 3 or 5 lights

Originally Toroidal Transformers were used, but later Electronic Drivers became popular.

If you trace the wire from one of the lights, it should lead you to the transformer. Sorry, but you may well have to lift a few floorboards in the bedroom. You should be able to spot those that have been lifted before. Generally, if it the halogen lights were a later addition, the transformer tends to be sited where the original light was installed, so that the existing 230v supply could be connected to it.

Some LED lamp manufacturers claim that their lights will work with the older transformers, but I don't have any experience of them to say that they do or don't. If they do work, they won't be dimmable.

 

[Gerrydelasel]

Maybe you could press a stethoscope to the ceiling and try to locate the hum...

 

[oldbutnotdead]

You might get lucky and find the transformer on top of one of the wall hung kitchen cupboards or in the pantry or the cupboard under the stairs (old house talk here, sorry, those are places I've stashed lighting transformers). As said, first job is to follow the cabling (in the ceiling space) to see where it goes.

And have you tried the LEDs on the existing power supply- if it was fitted ages ago it may well be a proper transformer (rather than a nasty switchmode electronic thing) and would quite likely run the things (though no dimming possible)

Final thought- are you sure they're 12v and not 240v halogens? (as in does it say 12v on the side of the lamp or you've put your multimeter across the supply and it shows 12v)?

 

[peejaybee]

Hi Guys

Thank you for your prompt and very helpful responses.

The wiring to the existing halogen lights is a real hotchpotch, two are connected in parallel, i.e. one light is wired directly to the other. As far as I can determine by peeking through the holes in the ceiling there doesn’t seem to be a common direction from which the lights are fed.

I’ve looked for the transformer in every nook and cranny around the kitchen area, above the cupboards, in the cupboards even in the bedrooms above the kitchen and the loft above the bedrooms.

I had the same thought about whether I could detect the hum of the transformer, quite possible since it will obviously be old with a copper wound iron core. I could buy a cheap stethoscope, just wondering which type, the doctor’s type with the disc shaped resonator or the mechanic’s type with the metal probe?

I’ve checked the existing wiring on my multimeter and it measures 12Vac. Unfortunately my new LEDs will not operate directly off 12Vac.

In the end I may have to resort to lifting the floorboards in the bedrooms above the kitchen but that will be a long and arduous task with still no guarantee I will find the transformer. I will update this thread of the eventual outcome.

Thanks for your help.