Low voltage kitchen lights

[JimboSelecta]

Hi all,

In my kitchen i've got 7 12v downlighters running off one switch. Recently they have developed a problem where only 2 of the lights work all the time. The other 5 come on from time to time but don't stay on for long when they do.

I've taken the fittings out and even had a look under the floorboards of the room above and from what I can work out the lights are running through a 250w transformer. I'm not sure at the moment but i think that the 5 lights that intermittently work are on a different transformer to the 2 that always work.

I've had an electrician round and he reckons its the transformer but hasn't fixed it this time around - I just want to understand the problem before proceeding any further.

Will replacing the transformer resolve my problem? I'm concerned that the lights work some of the time but not others, if the transformer was broken surely they wouldn't work at all?

Any help is much appreciated - cooking in the dark isn't fun

Thanks

Jimbo

 

[Space cat]

It's a pretty good bet that your 'transformer' is actually a switch mode power supply. In the old days, a transformer had an iron core with two coils of wire and it either worked or it didn't. Switch mode PSUs are stuffed with electronics and there are lots of ways in which they can fail.

One failure mode is where something inside overheats and the thing shuts down to protect itself. I suspect that's what's happening to yours. Another one is where it refuses to start when its too cold - or too hot - or its a Friday afternoon - aaaggghhh!

You might find that everything will work if you take one of the bulbs out but that's hardly a cure. You'll need a new transformer.

 

[JimboSelecta]

Thanks,

This is the transformer that I've found under the floorboards. Does what you describe happen to these?

http://www.thelightingsuperstore.co.uk/ni/popimg.asp?productid=13632

Oh and i've tried taking various bulbs out but no joy! One more worrying thing is that some of the wiring seems to have gotten very hot as towards the light end of the cable has gone brittle.

Any ideas?

 

[Space cat]

"DIMMABLE ELECTRONIC TRANSFORMER"

That says it all; it's a switcher - but it's not just an ordinary switcher.

Oh no Rodney! It's a BROKEN switcher!

One more worrying thing is that some of the wiring seems to have gotten very hot as towards the light end of the cable has gone brittle.

Check the terminals where the wires go into the light fittings. You might have a poor connection somewhere.

PS: This is a long shot but --

If the wiring is daisy-chained from one light to the next, a bad connection at the first one might just be the cause of all your trouble. Check this before you condemn the 'transformer'.

 

[JimboSelecta]

Thanks,

I've changed some of the connections where wires meet the light fitting and nothing has changed. I'll have another check on all of them.

Is it the right kind of transformer/switcher than i need considering i'm not using a dimmer switch?

Its also a bit wierd that its broken already beacuse it can only be a year old. Is there any way to be sure its not going to break again soon?

Basically assuming its the 'transformer' should i replace it with the same one again or do i need something different?

 

[securespark]

My experience is that the secondary wiring or connections are to blame.

Look at the connection between secondary wiring & lampholder wiring and the lampholder itself. These often fail or become such that they only work when they feel like it.