Light bulbs burn out too fast

[Andy]

Andy adds:

Here is a passage I found which has some suggestions that you might also want to consider:

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If you are burning bulbs to frequently you also might try using lower wattage bulbs. A 40 W bulb has a higher resistance than a 100 W bulb. Both bulbs will have the same voltage, the 100 W bulb must have more current. And that means the 100 W bulb must have a lower resistance. So the filament for the higher resistance 40 W filament must be heavier or have a smaller cross section. There is also a rough service bulb that is made with a heavier filament. It is important that line voltage feeding the bulb matches as close as possible the voltage rating of the bulb. If the bulb is rated for

120 volts and the feed for the bulb is 90 volts the bulb will be dim. If the voltage is 135 volts the filament will overheat and burn bright for awhile but will not last very long. The voltage tolerance is about 10 percent low or high. Since turning an incandescent bulb on and off doesn't shorten the life of its filament significantly, you do well to turn it off whenever possible. The same isn't true of a fluorescent tube--turning it on ages its filaments significantly (due to sputtering processes) so you shouldn't turn a fluorescent lamp off if you plan to restart it in less than about 1 minute. Always shut off all lights when leaving the house. Vibration can also cause shorter filament life. The best bulb on the market today is the CFL (Compact Fluorescent Lights) (Philips, Sylvania). These bulbs may cost 10 to 15 dollars, but will last about 10,000 hours.

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As I said, I have had good luck with Home Depot CFLs made by Phillips...... about $5 for a pack of four.....

Andy in Eureka, Texas PE

[Mark]

Bzzzzt.

the 100 Watt bulb will have a lower resistance and therefore a heavier filament and thicker cross section and be more rugged...

Mark

[JIMMIE]

I wouldnt worry too much about the spikes but tighten down the neutrals in your breaker box. Loose neutrlas can cause some interesting problems, like when my wife complained of her portable radio not working then it smoked when she used the toaster. Im glad we were living in an apartment when that happened. Kitchen outlets were on shared neutral circuits... this can put 240 at a 120 outlet

Jimmie

[hrhofmann]

Mark is correct

[Andy]

Andy comments: It seemed so to me, too. But I got curious about it and did some googling about filament size versus bulb wattage and came up with the following passage :

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The filament is longer in a higher wattage bulb and the resistance is lower, so more current flows through the filament, creating more heat and light, but the heat is spread out over the longer filament which prevents the filament from over heating, so the filament in a bigger bulb isn't any hotter than in smaller wattage bulb and hence the spectrum of wavelengths is the same for different sizes of bulbs.

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So, if the filament is made with a lower resistance, it is probably thicker, as Mark says, but a higher wattage bulb would have a longer filament, as it would be at the same temperature and needs a greater length to put out more light.....

The greater length would probably result in a more delicate structure and easier to burn out. Remember, the fungsten filament is over 6 feet long, but coiled and wound down to only an inch or two..... This would tend to verify the passage I copied previously from a manufacturer's website, which said that higher wattage bulbs are more susceptible to burnout....

Light bulb construction is something that I've never thought much about, and this exercise has been fun....

If you have any observations about filament lenght/size/fragility I'd be interested in learning more...

Andy in Eureka, Texas PE

[Rebel1]

It turns out that the kitchen fan was part of the original house, built in 1976. At that time, it was probably just a bedroom fan, which 9 years ago became subdivided to create a new apartment. None of the circuit breakers that control the rest of the apartment affect the kitchen fan/light. That breaker is probably in the garage. So it is possible that aluminum wiring was used in the original building. I'll check when I examine the breakers in the garage.

At this point,the problems are:

1) just a single bulb in the kitchen fan burns out prematurely, which is located on old wiring that does NOT cause problems in the other second-floor apartment, and 2) some of the bulbs on the new wiring burn out prematurely. I may take my o-silly-scope there to look for spikes over the weekend. I'll report my findings.

R1

[hrhofmann]

aha - This is the first time you gave any indication that you were especially knowledgeable about noise spikes and oscopes.

[Evan]

You shouldn't be touching anything in this "apartment" your friend should report the issue to the landlord who can either rectify it or eventually have the issue reported to the building inspector who would probably immediately condemn the entire building for the illegal occupancies...

The landlord has someone they can vilify (a.k.a. YOU ) as someone who was tampering with the wiring without any authorization if the building suffers any sort of electrical fire in that unit...

If your friend is that concerned about the cost of light bulbs he can do one of several things:

1.) Leave the offending socket with a dead lamp in it and not worry about it until it catches on fire... 2.) Demand that the landlord either fix the problem or keep him supplied with free light bulbs... 3.) Report it to the building inspector and watch as his landlord gets in serious trouble...

~~ Evan

[TKM]

Earlier, there was a post that mentioned vibration. My experience is that bulb vibration failures are more common than high voltage or spike problems. That particularly applies here because the main problem bulb is in a fan.

One solution is to use a "vibration service" bulb which has extra filament supports and thicker filament wire. Sometimes such bulbs are packaged as ceiling fan bulbs. Noise, which causes vibration, can be the culprit too. Traffic and aircraft noise can be picked up by the walls and ceilings of a building and cause them to vibrate which shakes the filament. New bulbs are not particularly sensitive; but, as the bulb burns, the filament becomes thinner and more brittle, so the bulb burns out early.

TKM

[Rebel1]

Problem is, the tenant is a life-long friend of the landlady. She even went so far as to say she would give her life for the landlady. I don't know what event, decades ago, created such a strong bond. Even though the landlady lives in the same building, my friend and her rarely see each other. Yet that bond remains. So calling the building inspector is not an option.

Yesterday, I replaced a closet light fixture. Cost only $5.97+7% sales tax. My friend wouldn't even deduct that trivial amount from the next rent check.

It will be interesting when the town undergoes a complete revaluation. There is a deck and shed added without permits. Then there are illegal apartments. I don't know if any town-wide revaluation is scheduled. But I certainly wouldn't want to be in the landlady's shoes.

[Rebel1]

I examined the line voltage with an oscilloscope, hoping to find it loaded with spikes or have an oddball shape (triangle-like or clipped). Looked perfect, both from black to white and black to green. Next time I'll check the circuit breaker box for loose connections.

Even though the voltage measures about 120, I'll get her 130V long-life bulbs. I turns out that the bulbs that go the soonest are the ones that are switched on most often.

In the kitchen fan, which is rarely used, I pulled up the center contact in the one socket (out of three) whose bulb blows most often. When I replaced the bulb, I did it with the power on and tightened the bulb just about 1/4 turn past the point it lit, as someone suggested, to prevent overtightening. I can't see an easy way to replace just the socket, and replacing the whole fan assembly is too expensive and not worth the effort.

Thanks, everyone, for the interesting comments and suggestions.

R1