Short Incandescent Lamp Life
Mike, The lamp life of incandescent bulbs
at three of my fixtures in my home is very short (average 2 -3 weeks in most fixtures). I checked
the voltage and it seems normal (118-126), I provided transient voltage surge suppression and I check
the center tab connections in each lamp bases. The fixtures that give me the short lamp life are of
the glass-enclosed type and I have this problem in the summer and the winter. I even have this problem
after removing the glass enclosure to the fixtures! What could it be?
From: Al Davis
I've seen short bulb life with just a few
volts higher than normal; over time, I think it shortens their life. Try a 130-volt bulb, it worked
From: Brian C
Are the lamps of the same manufacture?
Possible bad batch of lamps. Possibly the lamps are marked with the wrong voltage rating?
From: Dave Weinberg
If your voltage is correct and you are
not trapping too much heat (i.e. correct wattage lamp for the fixture) you might try a 130V lamp.
Also, try different manufactures of lamps. Keep in mind you get what you pay for.
From: Earl Dean
I have found high voltage, excessive heat
buildup, and vibration to cause rapid bulb failure. I have two incandescent fixtures on the face of
my garage. I discovered the vibration from the opening and closing of the door to be a cause of failure.
Use screw-in type fluorescent bulbs and watch for door slamming.
From: Edward C. Ley
We have the same problem at a private school!
Voltages are fine and incandescent bulbs just don't last in the glass-enclosed fixtures located in
the outside walkways.
Have you noticed aluminum screw shells
and aluminum bases on the bulb? Maybe brass base bulbs would solve the short bulb life. The extra
heat could be caused by corrosion on shell socket or possible a lose fit.
From: George R. Corron
Many of the lamps purchased at hardware
stores are only rated 110 volt, decreasing their life span markedly. Purchase lamps marked "130
volt" and see if your life expectancy increases. If that does not do it, find someone with a
chart recorder, and record your phase voltage, and then Neutral anomalies for at least a 24-hour period.
Vibration is the most common culprit when
it comes to short lamp life. If, for example, you live near an airport, railroad, or busy street,
expect shortened lamp life. If you have low-level vibration, you may not even be aware of it but your
lamps know that it is there. If your voltage is even a little high in an area with vibration, you
can experience extremely short lamp life.
From: Glenn Huntley
I brought this question up in class the
other night, the first answer or rather question surprised me. Does this guy live near a railroad?
The instructor used to have the problem in a place he used to live that was near a railroad and of
course the house vibrated pretty good, knocking out bulbs and things.
From: Haskin, Donald M (DynCorp)
Are you using 130-volt bulbs? Some stores
still sell bulbs rated at 110 volt. These bulbs usually have a short life when used at the 120 – 125
volts we see in most houses in my area. If the bulb is exposed to vibration such as near a door that
is frequently used, this can also lead to a short life.
From: Heit, Paul
Mike, My brother has a fancy dining room
lighting fixture that had this problem. The lamps have candelabra bases; the fixture bases have fixed
center posts (not spring copper). The problem is the cheap Chinese/Polish lamps. The center of the
lamp base had barely enough solder on it to terminate the filament. I simply re-soldered the lamp
bases, putting a nice spherical lump of solder on them. Now the lamps last a long time. Evidently,
the lamps were flickering due to a poor connection, stressing the filaments and breaking them, even
though you could not see the flicker.
From: Howard Chapman
This problem seems to be very common. I
would suggest you do as I did and the same as the large oil refineries do. That is to use 130-volt
lamps on a 120-volt circuit. You lose very little light output and the lamps last for a long time.
I bought my 130-volt lamps at Sears.
From: Jody Wages, email@example.com
It sounds like this location has higher
than normal voltage or surges that affect the life of the bulb. I recommend the use of 130V bulbs
for locations of this type. I also recommend these bulbs for fixtures that are hard to reach. I installed
this type of bulb in my home when we finished construction and have not replaced one in 7 years.
From: Joe Freeman
Several items to check would be lamp wattage/voltage
compatible with enclosed fixture (<100watts?) Power dips or surges from large switching loads such
as AC or other motors and of course the quality of lamps.
From: Keller, Paul E. - Tilden Lobnitz
Have all the neutral connections been checked?
Especially the multiwire circuits and the service neutral & grounding. Some utilities have overvoltage
problems when their load is reduced in the evenings. Try using a recording voltmeter for a week.
From: KEN TEVERBAUGH
At most electrical supply, or builders
centers you can find a small device that fits into the socket of the lamp. It dampens the voltage
spike that occurs each time you turn on the lamp. This will greatly increase the life of the average
bulb; also try using a lower wattage bulb.
From: Kendall Swenson
Mike, as you well know there are several
reasons for short lamp life. Some questions come to mind when I read this problem.
1) How long are the lights left on?
2) Is there any vibration in the building?
3) What is the voltage of the lamps?
What I would do to try to solve the problem
is try rough service long life 130-volt lamps or change to fluorescent lighting.
From: Matthews, Steve Mr. PW
Are these fixtures all on the same circuit? It may be
a loose connection in the outlet box... i.e. a loose neutral.
From: Michael White, Mwhite2690@aol.com
I have run into this before on several
occasions. Most usually, I found that the fixtures were installed in high vibration areas such as
near doors on frame walls. The added vibration was shortening the lamp life. In one case, we mounted
the fixtures on a piece of rubber to isolate them from the vibration. In another case, we changed
the fixtures to miniature florescent fixtures. Both of these seemed to work, but I prefer the last
one not only did it stop the short life it created more light for less energy.
In addition, the rubber was not the best
looking thing I have ever done to a fixture, but the customer did not want to spend the money for
new fixtures. On one other occasion, I discovered that the lamp base was not of good quality and as
soon as it got hot, the internal connection would lose contact creating even more heat. I replaced
the sockets with a higher quality ceramic shell with a bolted connection rather than a riveted one
this worked so well we were back to fix most of the rest of the fixtures in the house. The ceramic
lamp holders can even be purchased at Home Depot for about three dollars each.
Check the voltage! Are you sure it is correct?
Is there vibration from above? Install rough service lamps and be sure they are rated 130-volts. The
lamps will burn slightly dimmer, but will not get as hot and they will last much longer.
One solution is to go with a higher voltage
lamp 130 volt instead 120 volt. Another solution is to install “rough service” or “traffic signal”
lamps, which have heavy-duty filaments.
From: Rick Hollander
Check neutral connections
From: RON LYDA
Place a voltage recorder on the lines for
2 days and each check for high and variable voltages.
First, I would suggest that the voltage
be monitored over a period with a recording voltmeter (preferably a Dranetz or similar if available
- check with the local utility). It could be that the steady state voltage is acceptable but has periodic
Second, the TVSS should be a type with
diagnostic indicating lights. One of the ratings of TVSS devices is MCOV (maximum continuous operating
voltage). Many devices have a standard MCOV of 130V. If it sees in excess of 130V for some period,
it could fail. Without diagnostic lights, it could be unknowingly nonfunctional.
From: Scott E. Thompson
Try checking the voltage over a period
of a few hours and at various times of day to see if it gets higher than 120 VAC and stays higher
for some time. TVSS protection will help with spikes and surges, but not a rise in continuous voltage
unless it exceeds 300 - 400 VAC to ground. Other factors that might contribute to extremely short
lamp life would be:
* Excessive heat during operation,
* Shaking, bumping or other types of vibration
shock which would bounce the filament while in operation,
* Check branch circuit connections, if
the neutral comes loose this could cause the lamps to run "in series" with another loads.
If the common neutral connection randomly becomes loose between the first junction point and the panel,
and is used for a multiwire branch circuit, the circuits on the "load" side will be in a
series circuit between the two ungrounded conductors. The voltage impressed on each load can be figured
by the impedance of the series circuit.
Lastly, try using 130-volt [or higher]
lamp to see if it lasts longer than the 2-3 weeks limit experienced before. If that works and lamp
lasts at least somewhere close to it's rated life expectancy, use higher voltage lamps in problem
Since there aren't any complaints about
other fixtures, and/or appliances, (such as the TV, fridge, etc.), my recommendation would be to purchase
better quality lamps, even upgrading them to Fluorescent types that screw in. He has probably been
replacing the cheap lamps with the same cheap ones and therefore continues to have the same problems.
This isn't an electrical problem, unless it only happens with one particular fixture.
1. What is the tested voltage of the system,
and what voltage are the lamps rated?
2. Bargain basement lamps are normally
rated around 110 vac. If the system is 117vac to 125 vac, the lamps will not last. If you really want
your lamps to last, buy lamps rated at 130 vac.
From: Steele, Michael
When you checked the center tab in the
socket, did you mean the tab's connection to the wiring or the tab's connection to the bulb? I had
this same problem with a glass-enclosed lamp. The problem in my case was the center tab was not firmly
seated on the bulb connection and arcing would result between the tab and bulb connection. This would
result in decreased bulb life. The glass on the bulbs occasionally broke – the reason for this I do
From: Lynn Adams
1. Voltage that is 1-2% high can drastically
reduce lamp life. What is the voltage over a normal 24-hour period? Is there an industrial load that
causes voltage drop most of the time, which the power company has corrected, but allows line voltage
to rise when it is off?
2. TVSS is unlikely to affect incandescent
lamps, as they are not really a 'sensitive' load relative to semiconductors, electronics, etc.
3. Check the center tab of the lampholder.
If it is burned inside the socket it will cause excess heat transfer to the lamp and shorten life.
Also, check the rivet connections from the black wire to the center tab. This is often an almost indiscernible
source of heat and short lamp life.
4. With all respect, are you SURE the lamp
life is that short. For that single fixture? Several fixtures in an area, and replacing one of the
lamps ever 2-3 weeks is normal as you gradually work through the group.
5. Since the problem seems to involve certain
fixtures of the enclosed type, I would suspect damage to the socket/wire in the outlet box. Use the
Computer maintenance man technique. Change the fixture, put in a new lamp, charge a lot and the fixture
is burning when you leave. Actually, that is not a bad idea. If a replacement fixture gives you long
life, you'll have eliminated all the oddball and difficult possibilities and solved the problem. Just
install a few new, inexpensive (regular American manufacturers and types please) and see how long
the lamp lasts, by the calendar.
6. By the way, are they from a recognized
This sounds like a similar problem we had
in a condominium where bulbs all over the complex burnt out quickly. We narrowed it down to a vibration
problem. Weak construction allowed slamming doors upstairs to burn out ceiling fixture bulbs on the
first floor. Hard service bulbs corrected this problem.
Any transients that would be produced by
any electronic devices in the home would not have the magnitude to cause any problems with incandescent
From: firstname.lastname@example.org, Senior
The times that I've seen this problem it
was because of a poor neutral connection at any of several points. Usually the problem point was at
the electrical panel or the transformer. With a poor neutral the following symptoms would be measured:
Legs are balanced; each leg
to neutral should measure 120 volts.
No loads running, each leg
to neutral should measure 120 volts.
Some loads running but the
hot legs are unbalanced; there will be considerable voltage imbalance.
Consider the case where the neutral is
broken at the transformer. Unloaded there would be 240v leg to leg, and a weird and fluctuating voltage
leg to neutral. Heavily loaded there would be about 120v leg to neutral. If the electrical panel is
well grounded then the fluctuation may be less.
A poor ground grid would cause lightning
& safety problems but shouldn't cause light bulbs to burn out prematurely unless it is accompanied
by a poor neutral connection at the transformer or the electrical panel.
Spikes from power supplies (which include
SCR's, IGBT, power mosfets, diodes, transistors) have a very short duration and should not cause problems
with any appliance, especially light bulbs because the additional heating effect is minor. Consider
also that most people's light bulbs last a normal amount of time and most people have a house full
of electronics (microwave, TV, stereo).
I recommend leaving a min/max/recording
voltmeter connected across the hot leg and neutral for several days to confirm the problem. If only
low and normal voltages appear then switch, hot legs for a few days. Check the tightness of ALL neutral
connections in your electrical panel - especially the service entrance neutral. I would also call
your utility after you have checked your stuff carefully because there is a good chance that the problem
is at the transformer. If you have neighbors that are on the same transformer and if they have similar
problems then the utility is definitely suspect.
By far the biggest problem I have found
with shortened lamp life is due to loose connections. I have seen it more in the neutral conductor.
From: Dan Hicks, at http://www.ghgcorp.com/jevans/MyHomeRepair/liteBulb.htm
The bulb package should have an average life expectancy printed on it. The
typical light bulb is good for roughly 900 hours. At 10 hours a day, that's three months. At 24 hours
a day, it's a little more than a month. If you have 25 bulbs in your house burning an average of three
hours each day, a bulb will burn out every twelve days, on average.
If you compute the average life of a bulb and discover that it's significantly
less than the manufacturer's rated life, then you may have:
- Too high a wattage bulb in too small an enclosed fixture (such
as a globe), the heat can't get out--the bulb burns too hot, leading to short bulb life.
- Recessed lighting fixtures are often covered by attic insulation.
This blocks the intended ventilation method--heat builds up around the bulb, causing short bulb
- A vibration problem. Such as, bulbs under a heavily used stairway,
on or near an out of balance bathroom or ceiling fan, near a door that gets slammed, kids upstairs
jumping, etc. You can buy special shock resistant, also called "rough service" bulbs,
for this situation, or try one of the new miniature screw-in fluorescent bulbs.
- You may have over-voltage in your house. Occasionally this is
a serious problem. You can get a cheap multimeter at Radio Shack. If the voltage is over 125 volts,
talk to the power company about overvoltage. If it's a slight over-voltage, you can buy special
125V or 130V bulbs, though sometimes they're hard to find.
- Flickering. Reduce bulb life can be caused by intermittent electrical
contact which causes flickering which is like turning the light on-and-off constantly. It can
be caused by a bad light socket, or a poor electrical connection somewhere in the wires leading
to the light (most likely right at the fixture). Flickering can cause the bad connection to get
hot and possibly start a fire. If you don't locate the cause of the flickering and it affects
all or many lights, you could have a bad neutral connection -- a dangerous situation. Have an
electrician contractor check this out.
Most lights flicker all the time but you
don't realize it because of a psychological phenomenon called 'flicker fusion frequency.' The flicker
fusion frequency is usually about 25 hertz (cycles-per-second). A light that turns on-and-off (flickers)
faster than 25 times per second will appear to be on, steady. Your home's power cycles (60 cycle)
turns on an off 120 times a second, though it is only off momentarily, it's increasing or decreasing
the rest of the time. If you use a dimmer switch it turns the power to the light completely off for
a while 120 times a second. Of course, incandescent lights don't have time to cool down to dark during
these brief off times but they dim and brighten. Early movies were too few frames per second, that's
why they flicker. Whereas, later movies are frequent enough; so, though there are totally black moments
between each frame, you don't see any flicker.
Note: The 25Hz is an ordinary/average value. It varies based on the brightness/intensity
of the source and can go as high as 50-60Hz for very bright sources.
Some people sell 130 volt bulbs as 'long lasting.' If you have proper voltage, they will last longer,
but they're not a good deal -- they cost more per unit of light
Mike Holt’s Comment
The person replaced all of the fixtures,
used the same bulbs and the problem was solved.