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
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.
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
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...
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
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.
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.
Here is a passage I found which has some suggestions that you
might also want to consider:
***************Cut and paste *******************88
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.
*******************End of cut and paste ************************
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
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 :
**************** cut and paste *********************************8
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.
******************* cut and paste *****************************
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
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