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Something is wrong with my GU10 base LED light bulb or with the light fixture but I don't know what's at fault. The fixture/bulb doesn't work and has never worked (new install). The fixture was professionally installed. Now I've removed the light fixture from the mains and am trouble-shooting.

Trouble-shooting is challenging because I have only one fixture and one bulb with a GU10 connection.

With incandescent bulbs I could easily check to see if a bulb was damaged. A visual check of the filament was an easy initial check to see if the filament was burnt out and a test for (lack of) resistance with a multimeter would confirm whether the bulb had a complete circuit.

My multimeter doesn't report a complete circuit, even for a known good bulb of a different type ('regular' screw base) and I have only one fixture that accepts GU10 light bulbs.

I've checked the terminals on the base of light fixture and a complete circuit exists between the incoming (and outgoing) wires and the base in which the light sits.

My gut says that it's the light but I am not sure.

How can I easily confirm that the LED light bulb works the way I used to be able to with incandescent bulbs?

FYI this is a similar bulb as sold by Amazon.

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    Welcome to EE.SE! If you need to ask, then most likley not. Best case scenario you would be able to find what's at fault but it would not be worth the time to repair it anyway. – winny Aug 30 '18 at 15:14
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    You can't. You either need a second fixture or a second bulb. – Dave Tweed Aug 30 '18 at 15:15
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    The easiest thing to do is to buy a $3 bulb and see if it works. If it does, great, now you have a working light. If not, then it's in the fixture and you have only wasted $3 if you end up replacing it with a non-GU10 fixture. – Johnny Aug 30 '18 at 22:50
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Use the meter and carefully probe in volts mode these two points in the socket. You should read the same voltage as AC mains. Make sure you understand the dangers of probing mains voltage.

Also make sure that you are twisting the bulb in the right direction.

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  • I agree if mains voltage is available at the socket the driver in the lamp is probably bad, I have had this issue with quite a few lamps that have small integrated drivers. For larger fixtures with an external ballast I have had fewer problems but even these fail. If the lamp never worked I would try to exchange the lamp as this would cut the problem in half and if it works you know the lamp is bad if it still won't light it is doubtful that 2 lamps would be bad and the fixture wiring needs to be checked. – Ed Beal Aug 30 '18 at 17:53
  • Chuckle. I did have that thought but didn't want to play around with mains voltage. I wanted to know if it was possible to easily test an LED light bulb the same way you could an incandescent. My sense is the answer is "no". – Eric D Aug 31 '18 at 12:01
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You have 3 basic things to test.

1, the bulb. If you can, put it in a known working fixture. If it doesn't work, it's likely the bulb.

2, the fixture. Put a different bulb in it. If it works it's the bulb, if not, maybe the fixture or upstream. Move the fixture. Does it work now? You could, with care, connect the fixture to a spare wire and plug it into an outlet (just for testing).

  1. The wiring. Check it with a voltage tester, contact or non-contact type. If it doesn't work, then maybe it's the wire, or upstream the switch.

  2. The switch. Same applies here as 3.

  3. Upstream, the wiring from the switch to a junction box or a panel. Etc.

Since this is mains 110 to 240 voltage you may want an electrician to do it. Most importantly, if it never worked and was professionally installed, complain to the installer. They should have made sure it worked.

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