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In my kitchen, there are 5 halogen lamps, connected in parallel to a 12VAC transformer. The bulbs have rated life of 2000h, but I seem to be getting only about 60 hours out of them.

I measured the voltage at the terminals of the transformer to be 11.9VAC. The fixtures are well ventilated, I do not power-cycle them excessively and the rest of the devices in the household work just fine (my fluorescent bulbs are into their 5th year). I take care not to touch the bulbs with my oily hands when installing.

What could the problem be? A collegue suggested adding a voltage rectifier, but I believe the root problem is something else than the alternating current? Plus those guys seem to have some complicated chemistry going on inside them.

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  • The only thing I can think of is that the bulbs are of low quality. Do the bulbs actually burn out, I mean, do you see that the glowing spiral in the bulb is broken ? A rectifier will not do anything indeed, that is useless advice. The complicated chemistry is needed as a halogen bulb is like an ordinary bulb on a higher temperature. This would cause the wire to evaporate too quickly. The halogen gasses take care that the metal atoms go back to the wire instead of sticking to the glass. – FakeMoustache Feb 2 '16 at 8:46
  • Also: did you not touch the crystal glass of the bulbs ? If you did, then clean the bulbs with a spirit solvent to remove any oils coming from your fingers (you might not see that but it is there). These oils burn into the crystal glass. I always use a cloth when working with halogen bulbs. – FakeMoustache Feb 2 '16 at 8:47
  • Just swap-out to LEDs when they break. – Andy aka Feb 2 '16 at 8:55
  • @FakeMoustache, that's an advice I can work with. I'll shop around for a more sophisticated brand of bulbs. – Vorac Feb 2 '16 at 8:56
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    @FakeMoustache , the "rectifier" may be the simple diode half-wave rectifier trick, which reduces the power (and the brightness) so it may well work if the reduction in brightness is acceptable. – Brian Drummond Feb 2 '16 at 11:45
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@Andyaka, I know you don't need the extra reputation, but it would be cleaner for future viewers. Please copy your comments into an answer, so I can accept it.

Getting to the bottom of why the halogen bulbs have failed may be difficult. There is no technical reason for them to unnaturally fail but it could be a bad batch but my advice is not to replace the halogen bulb with another halogen type.

I'm swapping out all my old bulbs for LEDs everywhere in my house for reasons of long-term economy. It looks like your bulbs are G4: -

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And there are plenty of LED replacements coming into the market place now. This wasn't true 3 years ago. Anyway here are a couple: -

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  • I guess because the LEDs run at lower temperature, touching them with greasy fingers is not an issue any more? – Vorac Feb 2 '16 at 9:30
  • They do run at lower temperatures and I haven't read any warning labels saying they should not be touched (although I do tend to be careful when replacing them). Note also that not all G4 LEDs will "fit" into some tightly-spaced Halogen fittings so maybe buy one first to make sure it will fit. – Andy aka Feb 2 '16 at 9:34
  • It's been about 6 months since I began using your solution. Because I have spare halogen bulbs, those are also being used. Today burned out the first LED bulb (out of 3). Although 1 data point is not many, my conclusion is that LEDs keep running about twice as long as the halogen bulbs ... and cost exactly twice more. – Vorac Sep 24 '16 at 13:49
  • Furthermore, I have reached a conclusion about the reason the bulbs burn out. In another room, the bulbs are hanging by the wires, with no enclosure. Those haven't burnt out the past 2 years, although the get used about twice, compared to the first room. – Vorac Sep 24 '16 at 13:50

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