[tallguy]

Hello, and thanks in advance for any help that is offered.

The bulb in the light fixture over our front porch burns out frequently, approximately twice per month. It happens year-round, so it's probably not cold-weather related.

The house was built in 1950, and the fixture may be original, but I'm not sure.

Could this be caused by a loose wire, or will I most likely need to replace the socket? When we moved into the house, I replaced this fixture's toggle switch with a programmable timer switch. Could that be causing the frequent burnouts?

[leifweaver]

It is unlikely to be the programmable timer switch itself. If your bulbs did not burn out UNTIL you installed the timer, then you may have a wiring issue. If this has been an ongoing problem, then the most likely is that vibration from shutting the front door causes damage to the filament. Try replacing your bulb with a fluorescent or LED.

It IS possible is that it is a wiring issue, and that it is somehow getting surges, especially if the wiring is original. If you have EVER noticed your light getting slightly brighter or dimmer, then this may be the cause and you need to track down the wiring problem, as it may be a fire hazard.

[tallguy]

It is unlikely to be the programable timer switch itself. If your bulbs did not burn out UNTIL you installed the timer, then you may have a wiring issue. If this has been an ongoing problem, then the most likely is that vibration from shutting the front door causes damage to the filament. Try replacing your bulb with a fluorescent or LED.

It IS possible is that it is a wiring issue, and that it is somehow getting surges, especially if the wiring is original. If you have EVER noticed your light getting slightly brighter or dimmer, then this may be the cause and you need to track down the wiring problem, as it may be a fire hazard.

Thanks for your input. I have not noticed the brightness changing, but have not spent much time out there looking for that.

I have actually tried a couple of CFL bulbs in this location, but they flicker. I assume this is due to the timer, as I've noticed flickering in another CFL bulb on an interior lamp that's connected to a wall timer.

[leifweaver]

The timer switches the circuit through relay contacts. Any relay, switch, etc. that controls CFLs, should be rated for the high start-up current that the ballasts of these bulbs requires. What happens, when that is not the case, is that arcing occurs across the contacts as it is switched on and off. Carbon from the arcing, and pitting of the contacts, in turn, can cause resistance across the contacts and a corresponding voltage drop, until the voltage to the CFL ballast is too low to properly start it. Then you end up with flicker. (You will also end up with additional heat disipation at the contacts, which is not a good thing.)

This is probably unrelated to your standard bulbs burning out so fast. I still think that it is likely to be the vibration from the door. LED replacement bulbs are still fairly expensive. It may be cheaper to take out the timer that you put in and replace it with one that is rated for CFLs, unless you had it done by an electrician. Also, if it is not beyond your skill level, you might hook up your volt meter to the socket and see if you have surging, but do not risk electrocution. Good luck.

[KISS]

OK, look for signs of discoloration on the socket. Lightly sand if present. Put a light film of Vaselene on the lamp socket before installing the bulb. Inspect for loose connections at the timer, socket and breaker panel.

Vibration is a major killer, so is loose connections. CFL's are a different animal altogether.

If it doesn't work use a Bug lamp (yellow) and or an appliance bulb (which is hardened). Some 40 and 60 W appliance bulbs here: Appliance Light Bulbs

[tkrussell]

If the lamp is an indoor lamp, and is exposed to rain, the lamp will fail.

If the issue was overvoltage, other lamps in the home would be affected also.

Connecting a standard RMS volt meter will not capture "surges". This requires special recording equipment.

Vaseline is no-conductive, so that will cause more issues.

I suspect either moisture or vibration from traffic.

You can get "rough service" incandescent lamps, or find a compact fluorescent lamp that will fit in your fixture and rated for cold temperatures.

A defective lamp holder, or one with pitted bottom contact, can help burn out a lamp also.

[tallguy]

If the lamp is an indoor lamp, and is exposed to rain, the lamp will fail.

if the issue was overvoltage, other lamps in the home would be affected also.

Connecting a standard RMS volt meter will not capture "surges". This requires special recording equipment.

Vaseline is no-conductive, so that will cause more issues.

I suspect either moisture or vibration from traffic.

You can get "rough service" incandescent lamps, or find a compact fluorescent lamp that will fit in your fixture and rated for cold temperatures.

A defective lamp holder, or one with pitted bottom contact, can help burn out a lamp also.

Thanks to all! I'm leaning towards vibration from the front door. It's a very heavy, solid wood slab, and seems to slam very easily (especially since I replaced the warped sweep). Not to mention my wife makes no attempt (ever!) to close it gently.

I'm going to look for a rough service or appliance bulb (and inspect the fixture closely when installing it). If that still proves problematic, I'll check all the connections. If they're okay, I'll try replacing the timer. If still no luck, I'll check with an electrician.

Thanks again!

[tallguy]

UPDATE: I stopped by Home Depot a few weeks ago to get a rough service bulb. The clerk showed me a bulb that was labeled as having a shatterproof coating on it. Instead, I found a garage door opener bulb, labeled as having a vibration resistant construction. It seems to have a reinforced filament. Seems to working well so far!

[KISS]

Thanks for the feedback.

[stew_1962]

Another tip - look at the voltage rating of your bulbs. If you are in fact getting some surges, a 130V light bulb will last longer. They aren't that hard to find. I've used them for years and have had much better service life.