Why did this light go off with a bang and a spark?

March 25, 2013 9:33 PM

We had lots of wiring replaced recently, including two lamps connected to a dimmer switch; the dimmer was also replaced. Yesterday we noticed that the dimmer was now only allowing fully on or off. Today the light went off with a loud popping sound and a visible spark from one of the lamps, though both bulbs themselves work fine. What happened and how do I fix it? Is it likely just a faulty dimmer switch? Do I need to turn off the circuit (which has many other lights on it) as a precaution?
posted by parudox to Home & Garden (8 answers total)

Response by poster: I went ahead and turned off the circuit for now, we can do without it.
posted by parudox at 9:40 PM on March 25, 2013

What type of bulbs did you have in the light fixtures? CFL, wattage, brand?

Also, are these self-standing lamps, or wall-mounted light fixtures?

Is the dimmer controlled by dialing a knob, or what?
posted by sebastienbailard at 9:52 PM on March 25, 2013

Response by poster: They're regular incandescent bulbs, 60W I think. It's two wall mounted fixtures. The dimmer has an on-off switch and a slider.

I'm going to bed, so I hope that's sufficient clarification...
posted by parudox at 10:04 PM on March 25, 2013

You are probably using the wrong kind of bulbs/wrong wattage. I've had this problem, but that's the extent of my electrical knowledge...my dad fixed it for me ;).
posted by catatethebird at 3:36 AM on March 26, 2013

You are probably using the wrong kind of bulbs/wrong wattage.

60 W incandescents should behave themselves with a dimmer.

I'd double-check that the bulbs are not CFLs masquerading as incandescents, however.

If it isn't the case that it's CFLs being sneaky, I'd get an electrician in to sort it out. Possibly a different electrician from the one who did the installation. (If you knew that the fixtures and wiring are good, you could just replace the dimmer. But you don't know if the fixtures and wiring are good.)
posted by sebastienbailard at 5:46 AM on March 26, 2013

How do you fix it? If you don't already know how to do it, I'd say call the people who installed it, tell them that it isn't working and that there are sparks, and tell them they need to come and fix it before it burns the house down. Electricity is something you don't mess with if you don't know what you're doing, because mistakes can kill you, or burn your house down, or both. If the dimmer was working properly before, but isn't now, it's quite possible the dimmer switch is faulty, but unless you know how to properly troubleshoot the problem, this is one I'd leave to professionals.
posted by markblasco at 7:06 AM on March 26, 2013 [2 favorites]

Best answer: It's likely a faulty dimmer switch, NOT the bulbs. That you had it replaced recently and that the on/off behaviour started the day before points to the dimmer switch.
posted by SpecialK at 9:53 AM on March 26, 2013

Response by poster: Thanks everyone. I replaced the dimmer switch with a new one of exactly the same kind and it works fine now. I'll be in touch with the electrician to see if they suspect any other issues.
posted by parudox at 8:29 PM on March 26, 2013