What causes a light to turn itself off/on?

So the house I live in is pretty old and I noticed the other day that one of the bulbs in the fixture in the living room had gone out I thought I just needed to replace it but a couple of days later it just started working again.. Could this be a wiring problem? Or possibly just a bad bulb? It only happened the one time but now im afraid to use the light I don't want it to cause an electrical fire.

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  • 8 years ago
    Favorite Answer

    I have a hunch its actually in the fixture. I dont know if you have someone handy around but if you shut the power down at the breaker box to the light. inside where you screw the bulb is a little tab that makes the connection to the bottom of the bulb. After long use these tabs wear down and push in making a weak connection. simply pull it out a bit and screw in your bulb that will most likely be your issue.

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  • John M
    Lv 7
    8 years ago

    Somewhere in the circuit there is a contact that is moving a little bit and that movement is causing the current to flow or not flow according to the position of the contact. My first guess is the little metal tab that makes contact with the metal on the bottom of the light bulb. Since the house is old, it may be challenging to be sure that the power is out when you go to adjust it, so my advice is to shut off power to the entire house before you make this adjustment.

    To adjust the tab, remove the lightbulb and take something thin with a bend at the very end, such as a dental pick or a pick that comes with a nutcracker set, or anything else that can reach under the tab and bend it so it sticks out a little more. While you are doing that, check it for corrosion, and if you see any, scrape it off with something until you can see a good metal contact. Then bend in place and test. When you test it, be sure to use a "known to be good" lightbulb. This is one that has worked reliably in some other fixture without ever going on and off unless switched to do so.

    If this doesn't solve the problem, I would inspect the switch for loose wires. check any wire nuts in the junction box behind the switch as well. If all are snug, replace the switch to see if that solves the problem.

    If the problem still remains, remove the cover to the breaker panel (after shutting off power) and confirm that the black wire at the breaker is tightly affixed, and that the white wire at the neutral/ground bar is also tightly attached. If anything was loose, tighten and test. If all was tight, replace the breaker

    If that fails, look to the source of the power feeding the switch, and confirm that the connection on that end is secure. Often that is the outlet closest to the fixture on a line from the location of the panel.

    Best of luck!

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  • 8 years ago

    It could be a loose bulb, dirty contact on the socket or the bulb, or a wiring problem.

    Try tightening the bulb or turning it back and forth a couple of times to make the conductors wipe against one another - that's often sufficient to restore good contact. Just be careful if the bulb doesn't want to turn - DON'T force it, as it may break. Put on gloves or use a towel or rag to hold the bulb if it needs to be turned with any amount of force.

    If the roof has leaked and the socket or bulb is corroded, you should have an electrician replace the socket (after the roof is repaired, of course).

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  • muley
    Lv 5
    8 years ago

    The connection from bulb to fixture is not good. Any concern with an electrical problem is best sorted out by an electrician.

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  • Marko
    Lv 6
    8 years ago

    I think Raghaven is right. If it is a can light, up in the ceiling, those have a heat sensor that will break the circuit and then close the circuit when the fixture cools off. There may be insulation on top of it that is causing it to heat up so you need to go up in the attic and look.

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  • 8 years ago

    both of the faults you mention could be the reason for the bulb to re light .Best to change the bulb and see if the light does this again it may be as simple as a lose fitting on the bulb

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  • 8 years ago

    ...it could also be a broken element in the bulb. A door slam or somebody walking upstairs caused enough movement to wiggle the broken element to a place that it is currently making contact, but will normally go out again, soon.

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  • 8 years ago

    loose wire

    or a bad switch

    Source(s): maint man
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  • Anonymous
    8 years ago

    It may be due to over heating of the bulb or due to low voltage.

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  • 8 years ago

    The presence of ghosts will do that as well...

    :-)

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