Author Topic: ceiling spot lights going off  (Read 304 times)

Paul

  • L'enfer, c'est les autos.
ceiling spot lights going off
« on: 15 November, 2021, 05:37:38 pm »
I've got these little lights in the bedroom ceiling. They're not really my cup of tea, but I can't be bothered to change them.

The issue is that after they've been on a while (an hour or more - which is quite rare) some of them (the same few each time) go out. I seem to recall that if I wait long enough they come back on again.

wassgoinon?
What's so funny about peace, love and understanding?

Re: ceiling spot lights going off
« Reply #1 on: 15 November, 2021, 05:40:51 pm »
Poor connection.
Stop using them until this has been resolved.
That's how electrical fires start.

Kim

  • Timelord
Re: ceiling spot lights going off
« Reply #2 on: 15 November, 2021, 05:42:00 pm »
Halogen or LED?

If halogen, the connectors have probably cooked and corroded, resulting in an intermittent contact that changes with thermal expansion.  Replace the connectors, and give the pins on the lamps a good clean-up (remembering of course not to touch the glass).

If LED, the usual failure mode is some of the individual LEDs fail short-circuit due to running too hot, which causes them to overload the driver, which cuts out, waits and tries again.  Depending on the design this cycle may have a period of anything from tens of seconds to a fraction of a second.

Paul

  • L'enfer, c'est les autos.
Re: ceiling spot lights going off
« Reply #3 on: 15 November, 2021, 06:01:17 pm »
Holy Toledo! Fire?

Right - I've switched them off!

They are halogen bulbs I think. What/where is the connector? When I was removing the same type of lights on the landing, I noticed that for every n lights there was a box doodad. Is that the thing? Or do you mean the bit the bulb goes into?

I'm hoping the latter. There is some access to the bedroom ceiling, but the hatch is small (45cm x 32cm!) and I have never tried it. The bedroom is an extension, and the loft space over it is quite a lot smaller. Also, undisturbed centuries years of spiders.
What's so funny about peace, love and understanding?

Kim

  • Timelord
Re: ceiling spot lights going off
« Reply #4 on: 15 November, 2021, 06:05:40 pm »
Typically halogen spots will run at 12V (it's the sweet spot for physical robustness of the filament - you do get mains-voltage ones, but they don't last as long), so there will be transformers (heavy and buzzy) or more usually these days SMPSUs (lighter, may suffer component failure) inline to provide this.  Normally they're just lurking in the ceiling void, and can be accessed by removing the light fixture and pulling the wire until they emerge from the hole.  Dodgy connections usually happen at the point where the 12V supply meets the lamp, where a current of several amps will be expected to cross a piddly little MR16 or GU10 connector, while being subjected to extreme thermal cycling.

(You can probably tell that I consider these things to be a work of Stan for general room lighting.)

Paul

  • L'enfer, c'est les autos.
Re: ceiling spot lights going off
« Reply #5 on: 15 November, 2021, 06:08:18 pm »
Which I think means no tinyhatchspideradventures?
What's so funny about peace, love and understanding?

Kim

  • Timelord
Re: ceiling spot lights going off
« Reply #6 on: 15 November, 2021, 06:09:07 pm »
Which I think means no tinyhatchspideradventures?

You might get to play stick-your-arm-in-the-dark-hole-and-see-what-bites...

Re: ceiling spot lights going off
« Reply #7 on: 15 November, 2021, 06:13:02 pm »
Typically halogen spots will run at 12V (it's the sweet spot for physical robustness of the filament - you do get mains-voltage ones, but they don't last as long), so there will be transformers (heavy and buzzy) or more usually these days SMPSUs (lighter, may suffer component failure) inline to provide this.  Normally they're just lurking in the ceiling void, and can be accessed by removing the light fixture and pulling the wire until they emerge from the hole.  Dodgy connections usually happen at the point where the 12V supply meets the lamp, where a current of several amps will be expected to cross a piddly little MR16 or GU10 connector, while being subjected to extreme thermal cycling.

(You can probably tell that I consider these things to be a work of Stan for general room lighting.)
My bold. This^

Feanor

  • It's mostly downhill from here.
Re: ceiling spot lights going off
« Reply #8 on: 15 November, 2021, 06:43:46 pm »
Yes, I have many 12v halogens lurking around here, and they all eventually succumb to the lamp-connector failure.
I have a bag of replacement connectors, and am working my way through them.

Typically, what you'll find is that if you get the lamp out of the fitting, but dangling on it's connector, then you can carefully wriggle the lamp in-and-out of the connector a few times, and it will go on and off.
Removing the lamp from the connector will show that one pin will look dark and corroded.
The pin on the lamp can be scraped clean, but this is a surefire indication that the connector really needs replaced in this case.

I've recently replaced most of my outdoor 12v halogens with drop-in replacement LED equivalents, and that will (hopefully) mostly eliminate this problem.

Re: ceiling spot lights going off
« Reply #9 on: 15 November, 2021, 10:41:40 pm »
I've had switch-mode halogen light transformers start to overheat and then flash on and off. It doesn't necessarily mean that there is a high-power bad connection that is getting really hot. It may just be the protection circuit shutting it off due to heat, or a bad connection on something low powered in the control circuitry.

It needed new transformers whatever.

All the lights are LEDs now. They seem to fail in the first year or never, depending on luck and how well they are made.
Quote from: Kim
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