Lights - Reduced Lamp Life Solutions (12/31/99)

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 for me.

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,

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 Cooper

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.


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,

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



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 overvoltage.

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 fixtures.


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 not know.

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 manufacturer?


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 lights.

From:, Senior Engineer

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:

1.      Legs are balanced; each leg to neutral should measure 120 volts.

2.      No loads running, each leg to neutral should measure 120 volts.

3.      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

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 life.
  • 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 overall.

Mike Holt’s Comment

The person replaced all of the fixtures, used the same bulbs and the problem was solved.

  Go to top of page
Newsletter Registration   |   Stay Connected:

888.NEC.CODE (632.2633) 3604 PARKWAY BLVD, STE 3, LEESBURG FL 34748  

Tell a Friend About This Site

  NEC® and National Electrical Code® are registered trade marks
of the National Fire Protection Association (NFPA).
  ©Copyright 2011 Mike Holt Enterprises, Inc.