The mystery of the failing Halogen - can you help?

[Simon Croft]

I'm hoping more electrically experienced minds than mine can point me in the right direction, because what's happening seems to defy all logic.

Our 13-year old house is approximately half LED downlighters and half halogen. Three of the halogens have gone intermittent, and one of them stopped working completely a few days ago.

When they go intermittent, they usually come back on if you give the lamp a flick with your finger.

I put a new lamp into the unit that has completely failed, but it doesn't come on. I've tried the lamp in another holder and it works. (And I've tried a different bulb in the failed holder...)

With my multimeter set to 9VDC, I can't get a reading off the bulb holder. I was ready to conclude the transformer had failed, but when I put an LED lamp in there, it flashed continuously, so the transformer must be outputting 12V, or thereabouts. Uh?

As the unit appears to have a transformer attached to it, I assume that if I remove the whole thing and replace it with an LED unit and driver, the fact the rest of the lamps on the circuit are halogen is irrelevant. Correct?

Also, as the unit is in a stairwell, which is the only exit, do the regs say I should install a fire rated unit?

Any help gratefully received.

 

[DetlefSchmitz]

I would very much expect it to be AC, not DC.

 

[SUNRAY]

I would very much expect it to be AC, not DC.

A couple of years ago I'd have been happy to state they are AC but I'm starting to find some are chopped DC now.

 

[DetlefSchmitz]

However it didn't register on an DC meter. Occam's razor.

 

[Simon Croft]

I appreciate the replies. Pardon my ignorance, but I assumed the transformer output would be DC. At my age, I should know better than to assume anything. So it's probably AC. Back to the meter. I suspect it will still leave the paradox of the transformer working on some level, but not actually powering the halogen lamp.

 

[flameport]

12V halogen drivers don't output DC, and they typically only output anything if a load is connected, so any attempt to test the output will usually result in nothing at all even if it is working.

, I assume that if I remove the whole thing and replace it with an LED unit and driver, the fact the rest of the lamps on the circuit are halogen is irrelevant. Correct?

Yes, although you don't need a separate lamp and driver - sling the existing lights away and buy some new GU10 downlights with GU10 LED lamps to put in them.

 

[Simon Croft]

12V halogen drivers don't output DC, and they typically only output anything if a load is connected, so any attempt to test the output will usually result in nothing at all even if it is working.


Yes, although you don't need a separate lamp and driver - sling the existing lights away and buy some new GU10 downlights with GU10 LED lamps to put in them.

Brilliant. Thanks.

 

[EFLImpudence]

Yes, although you don't need a separate lamp and driver - sling the existing lights away and buy some new GU10 downlights with GU10 LED lamps to put in them.

I take it you mean 240V lamps?

 

[RF Lighting]

Can you get GU10 lamps in any other voltage?

 

[Simon Croft]

I take it you mean 240V lamps?

Can you get GU10 lamps in any other voltage?

I took @flameport to mean 240V, as the all the ones I have are. If there is some variant, I wasn't aware of it. It sounds as if that would be my best bet, in that is inexpensive, easy to action, pretty bound to work, and I would reduce energy consumption if I do the whole lot.

So, I never get to work out exactly what's wrong with the halogens...

 

[flameport]

So, I never get to work out exactly what's wrong with the halogens..

Most likely is the lampholder, they get overheated, the metal contacts become weak and don't make proper contact with the pins on the lamp.

 

[Simon Croft]

Most likely is the lampholder, they get overheated, the metal contacts become weak and don't make proper contact with the pins on the lamp.

That certainly seems like a good match for what I've described, especially the 'tap it and it works' part. Thank you one and all. I know what to do now.,

 

[flameport]

I took @flameport to mean 240V, as the all the ones I have are. If there is some variant, I wasn't aware of it.

Other voltages can be had if people really want them, but for all normal purposes GU10 = 240V (or the nearest equivalent 230/220)

 

[EFLImpudence]

Other voltages can be had if people really want them,

Ok.

but for all normal purposes GU10 = 240V (or the nearest equivalent 230/220)

Well, not really - no more nor less than MR16 means 12V.

 

[Simon Croft]

Just to let you know, I ordered four units from TLC and successfully installed the first one today. That did the trick. Only two errors on my part: 1) I didn't realise the old transformer was a factory sealed unit with fixed tails, so I spent ages getting it open, only to discover I had to cut the wires anyway, and 2) they didn't come with lamps, so I had to put a halogen GU10 in there anyway.