Electrical Problem

[tpd586]

My mom voluntered me to fix a lighting problem for a friend of hers. THe problem is two small can lights mounted in a large wooden headboard. The owner said that they worked fine until a few days ago, and then both went out at the same time. They are controled by a single rotary switch giving you four settings, both off, both on, or either on by themselves. I first changed the bulbs, then I took my tester and checked from the outlet out looking for where the power cut out. I had power past the switch with the power being properly controled by the switch. I then checked the sockets, and to my surprise I have power at the socket. What am I missing. These sockets are for the small base 40 watt maximum bulbs, if it makes any difference.

[Tequila]

The first things I'd check are:
Bad bulbs - have you tested them in another fixture to make sure they work?
Low or high voltage - what's the voltage at the fixture? too low and th elights might not be turning on. Too high and the bulbs might be blowing out.
Overload protection - many can lights will detect an overheat condition and turn cut power.
Mechanical connection issue - there may be something not seating right when you put the bulb in, especially if they're some unusual twist-lock type bulbs.

Good luck!

[pelligrini]

If you're getting power at the bulb socket, then it's probably not an overheat condition. Check the new bulbs. Like Tequila said, maybe the new ones are shaped a little differently. I have some big can lights at the house where only Phillips PAR-38 lamps will fit. The GE and I think Sylvania PAR-38s won't fully screw in.

It might just be a coincidence that both of the lamps went out at the same time. Incandescents only last for a certain amount of on time. I put in three little halogen par cans above my kitchen sink last summer. All three bulbs went out last month within days of each other.

[LCHIEN]

If you're getting power at the bulb socket, then it's probably not an overheat condition. Check the new bulbs. Like Tequila said, maybe the new ones are shaped a little differently. I have some big can lights at the house where only Phillips PAR-38 lamps will fit. The GE and I think Sylvania PAR-38s won't fully screw in.

It might just be a coincidence that both of the lamps went out at the same time. Incandescents only last for a certain amount of on time. I put in three little halogen par cans above my kitchen sink last summer. All three bulbs went out last month within days of each other.

I agree with this poster.
You can blow out incandescents simultaneously with a hard shock if something banged on the headboard. If the new ones don't fit quite right then the sockets will have power but the bulbs don't go all the way into the base.

[eccentrictinkerer]

I had a strange one recently.

A light fixture was not working, but my tester (the kind that tests for an electrical field around a wire) beeped telling me that I had power.

After much head-scratching it turned out the neutral wire was bad. Ran a new neutral and it worked.

So now I make sure I have a good neutral, as well as hot wire.

[Uncle Cracker]

Sometimes those beeper tracers can be a bit too sensitive. They can recognize potential voltage, even when the circuit ampacity is not sufficient to actually produce useful work. This is especially true when a neutral goes bad, or a wire connector is "rotted out" to the point where there is unloaded voltage past the connection. You cannot get accurate readings from many digital meters nowadays (they're too sensitive, which is necessary in some solid-state applications, but not motors and lights) unless you load the circuit down with a lamp or transformer. Often, it's better to troubleshoot with a test light, or with an older voltmeter (with a needle gauge), because these units will load the circuit enough to eliminate those "phantom" voltages that can be so confusing.

[eccentrictinkerer]

Sometimes those beeper tracers can be a bit too sensitive. They can recognize potential voltage, even when the circuit ampacity is not sufficient to actually produce useful work. This is especially true when a neutral goes bad, or a wire connector is "rotted out" to the point where there is unloaded voltage past the connection. You cannot get accurate readings from many digital meters nowadays (they're too sensitive, which is necessary in some solid-state applications, but not motors and lights) unless you load the circuit down with a lamp or transformer. Often, it's better to troubleshoot with a test light, or with an older voltmeter (with a needle gauge), because these units will load the circuit enough to eliminate those "phantom" voltages that can be so confusing.

I agree. I use my test light before get the meter out. Even my so-called battery tester just checks for voltage. Doesn't load the battery at all.

[reddog552]

Wiggy

The old wiggys are good for this they place a small load on the circuit to give a true reading.