LV halogen downlighters fading and brightening randomly

I've googled for this but found nothing that really relates to the problem, though it's hard to form a search which doesn't produce references to 50Hz flickering or to use of dimmers, neither of which is my problem. So if this is an FAQ please point me to it ...

I had my bathroom/adjacent toilet completely "done" last August. The bathroom has five LV 50w halogen down-lighters in it, the toilet another three. The house wiring was done about a year before.

All was well for quite a while then one of the lights in the bathroom started to act up. It started by fading and brightening for a fraction of a second, then for seconds at a time, and over a period of two or three weeks (while we had calls in to the team that did the fitting) it went to being out for minutes at a time and then finally dead. It's not the bulb because it works OK in another fitting.

Then about a week ago another one of the five in the bathroom started with the same performance; it's got somewhat worse by now, and today one of the ones in the separate toilet joined in. (And we're starting to write breach-of-contract letters ...)

Can someone suggest what's causing this? I have a reasonable knowledge of electronics and what not, and can't imagine what's going on. When they finally do pitch up, how much of it are they going to have to have access to? I've insulated the loft since the job was done.

Reply to
Henry Law
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I've seen this recently.

I have some 12v halogens in my bathroom. They were powered by a traditional iron-cored transformer. They worked perfectly.

One day, no light. Transformer had died.

Replacement 'transformer' is not actually a transformer, but is a Switch-mode power supply.

It behaves exactly as you describe. Intetermittent 'flickering', for fractions of a second, lasting for up to a couple of minutes. Seems worse when caught out of the corner of the eye.

I suspect that the SMPS is just a bit shit. It is correctly rated for the load ( not over- or under- loaded. ).

I suspect replacing the 'transformer' with a real transformer will cure it.

Reply to
Ron Lowe

Interesting. I shall go and peer intently at it. Actually I shall start by trying to find "it" because all I've seen so far (while insulating the loft) is little oblong boxes, about 75mmx50x50, one adjacent to each individual light fitting. I haven't seen a single transformer/SMPS so far. Where's me torch ...?

Reply to
Henry Law

Those little oblong boxes *are* the transformers/SMPSs - or at least they are here.

Reply to
John

Yes that's what I thought; but the likelihood of _three_ of them (out of eight) going on the blink within a few weeks of one another has surely got to be very low. Er, hasn't it?

Reply to
Henry Law

Not if you get a bad batch, or they get hammered with voltage spike or you`ve been a bit generous with the insulation.....

Mode and IBL make the most reliable LV electronic trafos but cost a premium to some of the almost as good far eastern and European brands.

Adam

Reply to
Adam Aglionby

I'll go along with a shit power supply too.

Reply to
The Natural Philosopher

Its a bad connection somewhere, either on the bulb holder, he wire to it, or within the smpsu/transformer itself. Hook a multimeter onto the psu output and see if it varies as the lights vary or not. Hard to believe you have electronics knowledge.

NT

Reply to
meow2222

High frequebcy output on most LV electronic trafos can give strange readings even when working properly, lamp load should smooth it out a bit but substitution is really prefered fault finding method...

Good point about checking lamp holders.

Adam

Reply to
Adam Aglionby

Can be due to excessively long 12V lead from "electronic transformer". My mate had this issue in his new kitchen extension. First he changed the LV leads to about 12 inch long from 8 foot odd and light flickering/brightness issues went away. (I think it actually states this in the fitting instructions, LV lead no longer than 12"). Very unhandily the builder bolted all the transformers to a beam in the ceiling meaning holes had to be cut in ceiling to access them.

Then the next issue was the 50W "electronic transformers" cutting out after many hours usually on very hot summer evenings or winter Saturday & Sunday evenings when the heating had been on all day. So he changed all the electronic transformers to 100W (and/or 70W) ones and lights work 100% time no problem. I think the 100W/70W replacements came from TLC.

Reply to
Ian_m

snipped

makes no difference, what youre looking or is variation, not absolute value.

NT

Reply to
meow2222

snipped

makes no difference, what youre looking or is variation, not absolute value.

NT

Don't they have thermal cutouts? and you insulated the loft after installation? Usual cause is power supply playing up but I've seen quite few that were cured by simply letting the heat escape.

My threepennorth anyway ...

Jb

Reply to
Jb

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