Can Light - LED bulb won't work

10,649 Views | 21 Replies | Last: 10 yr ago by spanky
DeBoss
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So this is the strangest thing for me. I replaced all of my can lights with new LED bulbs. Every single light in my downstairs works just fine except for this one can light. I put 3 different bulbs in it and none of them will turn on. Those bulbs are now working in a different can light.

Is there a way the wiring on one can light was done wrong to where it won't support a LED bulb but will work with a standard or CFL bulb?
TLA02
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Is it on a dimmer?
LED lights are different and require a more expensive dimmer switch to work.
DeBoss
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No dimmer, no double switch, nothing fancy like that at all.
The Collective
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This seems basic and probably has nothing to do with your issue, but did you retest it with a non LED bulb? It is possible that perhaps you over tightened the bulb, and the bulb leads aren't making contact with the fixture.
DeBoss
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It was working just fine with a CFL and continues to do so. Just honestly doesn't like a LED bulb for some reason. I can't figure it out and was hoping something was wrong with the wiring or the can.
MGS
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Is the voltage off?
G. hirsutum Ag
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LEDs use a lot less power. Could it be possible that a socket needs X amount of wattage in order to get electricity?
Dr. Venkman
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quote:
Is there a way the wiring on one can light was done wrong to where it won't support a LED bulb but will work with a standard or CFL bulb?
Yes, incandescent and CFLs do not require correct polarity, but LEDs do. If the can is wired backwards, the LED would not work, but a CFL would.
DeBoss
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So how would I check to see if it is wired backwards? I've never pulled down a can light and looked at it.

And I think the voltage is not an issue because the other 20 LED's work in the can lights in my house, just this one isn't working.
Dr. Venkman
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Get a multimeter and test the socket. The center should be hot and the sides should be neutral. Touch the black wire to the sides and red wire to the center. It should read around 110V. If it's backwards, it would be -110V.

It may be like playing Operation to test like that so you could get a socket-outlet adapter to make it easier. The short slot is hot and the long slot is neutral.

edit: you'll need a ground to test polarity. I'm not sure how you'd do it for a socket.
chap
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What kind of LED bulbs are these? I think most replacement LED bulbs have onboard regulation to correct inverted polarity.
Waterski02
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I'd check the polarity as well. Though I believe the starter in the lamp corrects that as well. Since CFLs would have the same issue with their internal ballast. But.... Electricity is crazy sometimes.
UnderoosAg
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quote:
LEDs use a lot less power. Could it be possible that a socket needs X amount of wattage in order to get electricity?
no
UnderoosAg
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quote:
Get a multimeter and test the socket. The center should be hot and the sides should be neutral. Touch the black wire to the sides and red wire to the center. It should read around 110V. If it's backwards, it would be -110V.

Um...no. Power in your house is 60HZ AC. When a switch is flipped on, voltage is applied. The flow of current starts, increases, peaks, decreases, hits zero, and then switches direction and flows in the opposite direction. It again increases, peaks, decreases, and hits zero. Lather, rinse, repeat. It happens 60 times per second. There is no "positive" and "negative" as there is with DC. If you stick the leads of a voltmeter into the hot and neutral of a receptacle, it should read a nominal 120V. (There is no such thing as 110, 115, or 220 for that matter). If you take the leads out, reverse them, and stick them back into the receptacle, it will still read 120V.

When used to describe generic AC circuits, "polarity" refers to keeping the phase/ungrounded/hot conductors and the neutral conductors referenced to each other in the same way. This is why we now have polarized plugs and receptacles. This helps ensure the switch on the lamp/appliance/radio/whatever is always interrupting the hot as it enters the device. It minimizes the amount of the device that is energized when off. When all wired correctly, it would ensure that the shell of the lamp socket (for example), as opposed to the button or tab at the bottom, gets connected to the neutral. This means if you happen to grab the shell while futzing with the lamp when it's off, it shouldn't bite you.

I've played with the $3 Chinese LED A lamp replacements from HEB, and the $50 Acculamps from Lithonia. The only time we couldn't get one to work was when the damn thing was just a hair to wide/long/fat to fit in the fixture. In some cases, it was literally a bunt hair off.

If the OP's can lights have the metal tab at the base, bend it up and see if it will do anything.

In the meantime, I'd be interested in hearing how a CFL or LED, or more appropriately the CFL ballast or LED driver, is smart enough to tell one side of a 120V AC circuit from the other. I'll hang up and listen.

Macpappy99
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When I was looking at getting LEDs for my recessed lights, many of them required you to bypass the fixture's ballast in order for the LED to function. More recently there are more that do not require this.

On a side note. How would you test a recessed light with a G24Q base to tell if the ballast has gone bad?
DeBoss
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Holy schnikes. So it looks like I'm just going to see if the metal thing in the end of the can light just isn't sticking far enough out. That would be my first thought since bulbs that didn't work in that can works in others and every other can in my house works just fine with the LED bulbs I have.
UnderoosAg
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quote:
When I was looking at getting LEDs for my recessed lights, many of them required you to bypass the fixture's ballast in order for the LED to function. More recently there are more that do not require this.

Only one of about 20 isn't working. And the OP said

quote:
Is there a way the wiring on one can light was done wrong to where it won't support a LED bulb but will work with a standard or CFL bulb?

That to me says it's a plain ol' can light that will take a regular incandescent lamp, or a screw-in CFL, or now a screw-in LED, in which case there is no ballast to bypass.


quote:
On a side note. How would you test a recessed light with a G24Q base to tell if the ballast has gone bad?



If you have more than one can light, swap the lamp from the bad fixture with a lamp from a good fixture. Was it doing anything before it quit working? Noise, flicker? Are the ends of the tubes on the lamp black/darkened/burnt looking?

Macpappy99
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Just intermittently going on and off and now it won't light at all. Switched lamps and nothing. Don't even get the initial flash from the bulb like I do when I put a bulb in the other fixtures.
UnderoosAg
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Generally, the way to troubleshoot a ballast is swapping lamps, checking for power at the fixture, dropping an F bomb, and then just replacing the ballast.
big ben
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UnderoosAg, what's ur profession lol
UnderoosAg
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quote:
UnderoosAg, what's ur profession lol


I'm an out of work hair dresser.

UnderoosAg
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I'm also one of the guys who slaps ink on drawings that y'all love to hate.
spanky
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So I had the same problem with an LED bulb (Utilitech from Lowe's). Sure enough it was the spring clip in the fixture. Just pulled it up a bit and presto, light. The contact on the LED bulb is a little flatter than most old incandescent ones I guess.
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