Lights in ceiling fan go pop when switched

[Greg Stark]

So what exactly causes lights to go pop when they're switched on?

Because I have a ceiling fan that seems to work 100% correctly 99.9% of the time. But once when i was turning it on the lights went pop and the switch no longer worked. I replaced the switch and it worked perfectly for about 30s and then the same thing happened. I think both times it happened the fan motor was running.

The switch box has two cables coming in, one with just black/white and one with red/black/white.

I believe the black/white is the supply and the red/black/white is the ceiling fan. It's wired with white connected directly to white. And black connected directly to black. The switch is between the blacks and the red.

If I just remove the switch and leave black-black and white-white with the red disconnected the motor works fine. The strange thing (at least as far as my understanding of the situation goes) is if I connect black-red and white-white, which I would have thought would leave the lights on but the motor disconnected, nothing works. In fact neither do the other fixtures on the same circuit.

I'm beginning to suspect something elsewhere on this circuit is wired wrong. Or is it possible that I have a completely mistaken idea of what the red/black/white wires are?

[Joseph Meehan]

I have to take a guess here. The lamp died as it was switched on, not unusual, and the short very high load burned the switch as well.

Are you using lamps designed for fan (vibration) use? If not pay the extra cost and do so, it will be cheaper in the long run and they will be less likely to cause that problem. Also make sure you replace the switch with a high quality one, not the cheapest one at the DIY center.

[Don Klipstein]

Are you talking about the bulbs actually failing spectacularly?

If so, this is a complaint that I have heard of occaisionally. What happens is that when a light bulb fails, an electric arc can form where the filament breaks, and move to the ends of the filament where there is no filament resistance to limit the current. You get the bright blue flash. Most light bulbs have a thin fusible link in one of the wires inside. But I have heard of this internal fuse being omitted in some cheaper bulbs, and even for a little while in ones of one of the "Big Three" name brands. Without this internal fuse, burnout arcs have been known to draw enough of a current surge to make the internal wiring do something nasty (maybe fuse with a big, "explosive" spark or vaporize surrounding adhesive) and pop the glass bulb off the base. A more common problem with burnout arcs in bulbs lacking fusible links in their internal wiring is that the current surge can damage switches and especially dimmers.

Try a different brand of bulb, preferably GE, Philips or Sylvania. If these are "regular" (known as A19) bulbs, then store brand ones having life expectancy figures and lumen light output figures like those of "Big Three" ones are OK since they are actually relabeled "Big Three" ones.

- Don Klipstein ( [e-mail],

[Jimmy]

I had this problem after buying bulbs to support a charity. They were suppose to be great bulbs,Brass base. They were made in China gargbage. I bought 2 dozen and at least a third of them had bad connections to the base. The charity does good work so the next time they come around I will just give them a donation and they can keep their bulbs.

[Greg Stark]

Well failing with a loud POP. The bulb itself didn't break and the circuit didn't blow. The dimmer (actually an annoyingly expensive X10 dimmer) is no more. I replaced it with a normal dimmer and the same thing happened, it's dead now too.

I know what happened now. More or less. I opened up the fixture to find all the wires corroded and frayed. The shielding had completely flaked away. Whenever there was the slightest vibration, like from the fan motor, the wires touched and shorted.

I'm not quite sure why the bulbs blew. My best guess is the audio shock from the short which would have been right behind the bulb holder.

Huh. Conceivably this could have caused the flaked insulation and burn damage. But I'm more inclined to think it was simple heat damage over the last 15 years.

The corrosion is a mystery The fixture is not in a place where water or condensation would appear, and there's no sign of water damage in the area.