Why do my light bulbs hate me?
March 5, 2007 5:16 PM   Subscribe

Why do my light bulbs keep burning out?

I moved somewhat recently, and ever since, my incandescent light bulbs all go poof. It's not limited to a single circuit. The light above the stove, hall-way ceiling lights, table lamps, they all just keep on dying. Average bulb life must be around 1-2 months.

The house has no obvious electrical problems, though it was built about 25 years ago.

The CFLs all appear to work okay, but I'm concerned that a full switch to CFLs might just mask an electrical problem that will end up frying my other appliances.

What could it be?
posted by PEAK OIL to Home & Garden (17 answers total) 4 users marked this as a favorite
IANAElectrician, but this seems to cover some possibilities.
posted by CKmtl at 5:25 PM on March 5, 2007

I agree with the site CKmtl linked to, I had a house that, over 15 years, ate light bulbs like bon bons, a Mac Plus, a PC power suppy, 2 VCR's, the water heater and a freezeer full of food. All the events were spaced well apart [years in fact but all part of the same pattern] and never revealed themselves clearly until I could look back. Get 'er checked out and see if the place has surges.
posted by Freedomboy at 5:31 PM on March 5, 2007

My two cents based on nothing but personal observation: weather seems to be a big factor in light bulb life. I notice car lights mostly only go out in winter, and my lights tend to die in the winter, too. (Possibly also has to do with longer use during times when the day is shorter.)
posted by anaelith at 5:33 PM on March 5, 2007

I have the same problem here, and I have chalked it up to an old electrical system that's probably doing more than it's really intended to... I have several computers.

Awhile ago I replaced everything with the CF bulbs, and while the light isn't *quite* as nice, I have lost only one bulb in the last five or six months. Considering I was losing at least a bulb a week before, it's a big improvement.
posted by Malor at 5:35 PM on March 5, 2007

Just want to let you know I had the same problem in a previous house. Drove me nuts. We changed light bulb brands and that seemed to help.

I just did some googling and two suggestions seem most common.
Try a different brand.
The light bulbs may have been screwed in the socket too tightly.
posted by BillsR100 at 5:44 PM on March 5, 2007

Almost certainly it's because the power in your new place is particularly hot.

When I moved from Oregon to Massachusetts, one of the things I noticed was that light bulb lifetime was considerably shorter in Mass. It turns out that they run the power there at greater than 120 volts, whereas in Oregon it was less than 110 volts.

I agree that you should get a DVM and check the power line with it. (But be careful!)

It used to be possible to purchase a package of small disks, each about the size of a quarter, which you could put in a light bulb socket under the bulb. It was nothing more than a small series resistor, but it cut the effective voltage to the bulb, yielding somewhat less light but considerably lengthening the bulb's lifetime. I have no idea if those are still available, however.
posted by Steven C. Den Beste at 5:55 PM on March 5, 2007

Consumerist JUST covered this.

And I experience the same thing in my kitchen. Sucks.
posted by disillusioned at 6:44 PM on March 5, 2007

If you use those disks you will be wasting electricity through their resistors. I would just go to CFLs if the power really is hot. 120 volts is the US standard. My power is spot on. That one article says seven or eight extra volts halves the life expectancy? That seems excessive to me. I wonder how that works? In any event, multimeters are cheap. Home Depot, Radio Shack, Target all carry ones that can be had for probably less than twenty dollars. You really don't need anything fancy. Just be careful plugging the probes into the outlet. You can check the grounds with it as well. If you have three prong outlets, put one probe into the ground and then the other probe into the wider of the two slots (neutral). There should be very little or no voltage difference. If there is more than a volt or so difference you have a grounding problem. Call an electrician.
posted by caddis at 7:23 PM on March 5, 2007

Concrete-frame structures sometimes experience a mild vibration that loosens lightbulbs in their sockets. Yes, I realize this sounds bananas, but apparently it's true. Seems obvious and I don't mean to insult your intelligence but if you live in such a building be sure the bulbs are burned out and not just slightly unscrewed...?
posted by Mrs Hilksom at 8:04 PM on March 5, 2007

Response by poster: I don't mean to insult your intelligence

This imples that I have some ;-)

It's a wood-frame structure, and yep, they really are burning out. Looking at the available choices, over-voltage seems the most likely. Somehow that hadn't even occurred to me.

Thanks, AskMe!
posted by PEAK OIL at 8:08 PM on March 5, 2007

Replacing your wall switches with triac dimmers will vastly improve the life of your bulbs, as it allows you to automatically "soft start" the lightbulb, preventing the big inrush of current to a cold filament that snaps most old filaments finally. And, you readily regulate the level of light you want or need in the room, saving energy when you don't need full brightness, which is most of the time. I find that the Leviton 6693 illuminated clear toggle dimmer is a nice accessory for any incandescent room light control situation, and at $9.76 per device, you can do your whole home, in a couple of hours. The toggle switch is illuminated when off by an internal orange neon lamp, making it easy to find the light switches in a dark room, too. If you order 10 or more through Home Depot, they typically waive the special order charge and shipping.

Incandescent bulbs will last from 3 to 4 times longer, when operated on a dimmer, and it takes about 10 minutes to replace a standard two pole toggle switch with a dimmer. You can also obtain 3 pole dimmers, for situations like hall lights that are wired with 3 pole switches at either end of a hallway.

These dimmers don't work with most CFL bulbs, however.
posted by paulsc at 8:17 PM on March 5, 2007

It does seem excessive at first blush, but it's really not.

Filament temperature in an incandescent bulb is pretty much proportional to power draw.

If a bulb were a perfect ohmic resistor, power draw would be proportional to the square of input voltage. But because the bulb's resistance increases with filament temperature, it's not quite that extreme.

Even so, a 5% increase in operating voltage gives rise to something closer to a 10% increase in power draw (and therefore operating temperature) than a 5% increase.

Bulb filaments are made of tungsten, which has a very high melting point (3695K); but in order to throw a nice white light, the design operating temperature is not all that far below the melting point. Typical color temperatures for incandescent bulbs are around 2800K, giving about 900K of safety margin.

Crank a 120V bulb up to 128V, and that 6% voltage increase will give you at least a 10% power increase, winding the filament temperature up from 2800K to around 3100K. You're now only 600K below melting point instead of 900K below.

At that temperature, evaporation of metal from the filament is going to be much faster, and the filament is therefore going to break much sooner.

Quartz halogen bulbs are designed to work at these higher temperatures (typical color temperature for a QH bulb is around 3300K; they're noticeably bluer). The gas mixture that surrounds the hot filament in these bulbs, and the high temperature of the quartz glass envelope, encourages redeposition of evaporated tungsten back onto the hot filament instead of condensation on the inside of the glass envelope, meaning that the filament can be run closer to melting point without deteriorating as fast. But that's at design voltage. Run a QH bulb over-voltage, and you can easily make the filament fail by melting it.

CF lamps typically have an "electronic ballast" which is essentially a little switching power supply, similar to what you'd find inside a PC. You can kill these with overvoltage, but it takes more than a few percent; you need a decent power surge to finish them off properly. The way you'd kill a CF lamp is the same way you'd kill any other piece of power electronics: mount it somewhere unventilated and cook it. You only need to get it over about 100°C to do it in, and that's disturbingly easy to achieve in a lot of compact light fittings.

CF lamps also don't like the dirty, chopped input power they get from light dimmers. Incandescents, on the other hand, thrive on it - simply because it makes them run less hot. If CF's don't suit you for whatever reason, and you're blowing incandescents due to persistent overvoltage, try fitting dimmer switches. These will actually save you power, rather than waste it as inline resistors would do, and they won't overheat your light fittings.
posted by flabdablet at 8:53 PM on March 5, 2007

The inline disks I talked about don't necessarily cost you money.

Since the total resistance with one is higher than without it, less current flows. Some of the current is dissipated as heat in the resistor, and the rest becomes heat and light in the bulb, but less heat and less light than if the series resistor wasn't present.

The series resistor makes the whole system less efficient at producing light, but it also reduces the total current draw, if you don't increase the power rating of your light bulbs (i.e. you were using 60 watt bulbs and continue using 60 watt bulbs with the series resistor). In that case your electric bill will drop slightly.

If, on the other hand you go from 60 watt bulbs without a series resistor to 75 watt bulbs with one, then your power bill rises slightly.

But in both cases the amount is really very small, and it will be more than offset by the reduction in the amount of money you spend replacing light bulbs.
posted by Steven C. Den Beste at 9:21 PM on March 5, 2007

If your aim is to save money on lighting, CF lamps can't be beaten. Each CF lamp will save you about thirty bucks over its service life, compared to doing the same lighting job with incandescents (more, if your incandescents are consistently blowing prematurely).

If you really don't like the light out of CF lamps, and you just want to stop your bulbs blowing, a dimmer will save you more money than a series resistor doing the same job because it reduces the power delivered to the bulb by chopping it (actually switching it off for imperceptibly small periods) rather than wasting it as heat. Plus, at least some of the time you will be running your lamps at much less than full brightness, saving even more power.

The series resistor's main advantage over the dimmer is that it will be fairly easy to wind the dimmer all the way up to Eleven without thinking about it, in which case it will not be protecting your bulbs in the slightest. The series resistor is a simple fixed device that's always on the job.

Or you could always whinge to your power supply company and see if you can get them to drop the voltage on your block down a notch. If they got complaints from everybody in the block, they'd probably act on them (unless they're deliberately supplying overvoltage power so they can charge everybody more for the resulting overconsumption).
posted by flabdablet at 4:55 AM on March 6, 2007

Some bulbs are rated for 130V. Try those. They cost a bit more, but last longer too.
posted by kc0dxh at 7:46 AM on March 6, 2007

posted by mr. strange at 8:14 AM on March 6, 2007

Aluminum wiring from the 70s in the house can cause this sort of thing to happen when the aluminum loses proper contact with the neutral and causes a load imbalance. The age of your house makes it possible or likely that you have aluminum wiring.

You may need to be rewired.
posted by Jupiter Jones at 9:54 AM on March 6, 2007

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