12v Downlights not working!!

[HappyHippyDad]

Hello all....

I have recently been asked to put in 9 LED 230V downlights, which I have done.. all working fine. The reason was the old 12V halogens only had 2 of the 9 working and the customer said everytime she replaced a bulb they would either not work at all or only last a few days/weeks.

All connections were tight, bulbs were a reasonable quality and the voltage was not too high. However they were completely covered in insulation so I'm guessing the transformers were getting far too hot as they were very close to the 12v lights which give off a great deal of heat.

I have all the old transformers and bulbs at home and decided to test them, all bar one bulb worked fine which confused me a bit. I know very little about the thermal overload protection of a transformer but I'm guessing this was what was happening, but I have a few questions:

1. Do all (or most) 12v transformers have thermal overload protection?
2. When the temperature cools down should the transformers start working again or does the overload protection only work once and then the transformer is broken?
3. If they should start working again, as they did at home, why didn't they in the customers house? perhaps this wasn't the problem!

Thanks chaps...

 

[mrloy99]

hi,your thinking sounds about right to me...some tx's do have a thermal overload which resets when they cool,others don't....as you say perhaps this wasn't the problem....I find that lampholders are quite often the culprits or even sometimes the lamps themselves build up a sort of patina or coating on the pins,so work sometimes when you wiggle them.

 

[GLENNSPARK]

Hello all....

I have recently been asked to put in 9 LED 230V downlights, which I have done.. all working fine. The reason was the old 12V halogens only had 2 of the 9 working and the customer said everytime she replaced a bulb they would either not work at all or only last a few days/weeks.

All connections were tight, bulbs were a reasonable quality and the voltage was not too high. However they were completely covered in insulation so I'm guessing the transformers were getting far too hot as they were very close to the 12v lights which give off a great deal of heat.

I have all the old transformers and bulbs at home and decided to test them, all bar one bulb worked fine which confused me a bit. I know very little about the thermal overload protection of a transformer but I'm guessing this was what was happening, but I have a few questions:

1. Do all (or most) 12v transformers have thermal overload protection?
2. When the temperature cools down should the transformers start working again or does the overload protection only work once and then the transformer is broken?
3. If they should start working again, as they did at home, why didn't they in the customers house? perhaps this wasn't the problem!

Thanks chaps...

dont bother keeping these things to put on another job....get em slung....

 

[HappyHippyDad]

dont bother keeping these things to put on another job....get em slung....

wasn't planning on reusing, just wanted to do a bit of detective work! 12v downlights not working always seems to come up on the forum and I wanted to see for myself why that is, but after I found all the transformers working and all bar one of the lamps working it was a bit frustrating as I was no closer to finding the culprit!! Although I have to admit some of the lamp holders did look a bit worse for wear and clearly had some thermal damage to them.

 

[GLENNSPARK]

well...surely you know to test on the incoming side of a tranny thats not working to confirm....

and yep...some TXs have thermal overloads....a common example of this is where kev kitchen etc has been too tite to provide a TX for each load...and so rather than go get a suitable tranny that can cope with multiple loads...they use one one crappy little 50va job to run a load of downlites off....watch the lamps come on and off...all on their own....

 

[Silly Sausage]

Agree with MrLoy, those 12V lamp holders are about as useful as a Durex is for a happily married couple, and he's had the snip.

 

[tazz]

Virtual all electronic transformers have current and thermal overload to meet CE mark......and most are manufactured very close to their limit. so would always suggest over rating the driver for leds, and transformer for halogen, by a least 30%

 

[7029 dave]

Selv, more trouble than there worth.

 

[Lambretta phil]

When you tested transformers at home they weren't covered in insulation so they would work .try cover them and you will cut out until they cool down.

 

[tazz]

When you tested transformers at home they weren't covered in insulation so they would work .try cover them and you will cut out until they cool down.

Thats a fantastic idea.......wow.....none of us thought of that.....now we all realise what the problem must be....!!!!!!!!!!

 

[guest119]

Thats a fantastic idea.......wow.....none of us thought of that.....now we all realise what the problem must be....!!!!!!!!!!

Watch out Biff, youve got competition :wink_smile:

Boydy

 

[Lambretta phil]

Thats a fantastic idea.......wow.....none of us thought of that.....now we all realise what the problem must be....!!!!!!!!!!

sorry about my answer tazz I am new to the forum .Just tried to answer a the basic simple question 3 on op with a simple answer, instead of getting technical or taking the ****. I will try to get better.