Q&A / 

Light Bulbs Burn Out Quickly

DEAR TIM: Four of the six bulbs in the recessed lighting in our kitchen ceiling keep burning out. I just replaced one and it burned out in an hour. I am using 65 watt bulbs. Our house is only 3-years old. Are the bulbs the wrong size? Is there a problem with the wiring? Cory Dixson, El Dorado Hills, CA

DEAR CORY: The problem with the premature failure of the light bulbs has nothing to do with the wattage or the wiring. My first guess is that it can be traced to the person who has installed the light bulbs or previous owners of your home. I think they are twisting them into the socket too tightly.

The flickering of light bulbs in lamps and fixtures can also be caused by bulbs that have been installed too tightly into light fixtures.

Look right in the center of the photo. You can clearly see the brass tab and if you look closely you can see it is raised up off the bottom of the socket. PHOTO CREDIT: Tim Carter

Look right in the center of the photo. You can clearly see the brass tab and if you look closely you can see it is raised up off the bottom of the socket. PHOTO CREDIT: Tim Carter

At the base of light fixture sockets you will find a brass tab. This tab is bent at an angle when the fixtures are new and will spring back and forth if depressed slightly. Do not ever stick your finger in the socket to test this, as you can get shocked if the power is on to the fixture.

Take several new light bulbs and inspect the base of each one. You will quickly notice that the bottom of most light bulbs has a small droplet of solder in the center of the base. More importantly the size of this drop of solder is not consistent from light bulb to light bulb. It is close in size, but not always the same size or height.

If the brass tab at the base of the socket does not make firm contact with the bottom of the light bulb, a small electrical arc can happen that starts to melt the solder. Over a period of time, the solder can deform and the gap between the solder and the brass tab gets larger.

When this happens, the electrical contact between the brass tab and the solder is broken and the light bulb acts as if it has been turned off when in fact the switch is on and the bulb is still in working condition.

This is the bottom of a standard light bulb. You can see the drop of silver-colored solder in the black ring. This solder droplet is not always the exact same size in every bulb. PHOTO CREDIT: Tim Carter

This is the bottom of a standard light bulb. You can see the drop of silver-colored solder in the black ring. This solder droplet is not always the exact same size in every bulb. PHOTO CREDIT: Tim Carter

 

To prevent this arcing you must be sure the brass tab is always at about a 20 degree angle inside the bottom of the socket. People who twist bulbs in tightly will depress and flatten the tab so it does not spring back when a bulb is replaced.

If you discover the tab is flattened, then you must turn off the power to the lights, and as an additional safety safety measure, turn off the circuit breaker to the lights. Use a needle-nose pliers and carefully grasp the sides of the brass tab and slowly pull it up so the end of the tab is about one quarter inch off the base of the socket.

When you install a bulb always do so with the power on and the light switch on. As soon as the bulb comes on, only continue to turn the bulb one-eighth of a turn. If you screw the bulb in too tightly, you will once again flatten the brass tab.

Column EM0017

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7 Responses to Light Bulbs Burn Out Quickly

  1. I like this theory, unfortunately it is wrong at least in my case. With my bulbs (intermediate base 40 watt plugged into a ceiling fan) i can clearly see that the bulb is in fact blown, the wire between the terminals is broken and the glass is blackened on the bottom. My bulbs consistently last about a month which is just short enough to be super annoying. I was thinking about getting a base converter to either candelabra or the standard bulb size, that way at least i would have more bulb options and could possible get a more heavy duty bulb. Do you think this is a good idea?

  2. For Dallas, I would think that maybe when the solder melts it lets air get into the bulb and it promptly blows the filament. Just a thought. Bend the tab up as suggested and see if the problem goes away.

  3. Tim, thank you very much. I was having the same problem. I installed 12 can lights with no problem. I tried to "straighten" a bulb in one and broke the bulb. After that bulbs kept burning out fast. I think your theory is correct. If the contact is not good with that brass tab, then the arcing will generate a lot of heat, which quickly causes the bulb to fail. I had a suspicion it might be something like that, but it's great to find your confirmation by Google search. You saved me a lot of headaches trying to pull out the can light from a just finished living room :)

  4. hi, i have my house running on 220v 50w down lights
    but they keep on burning, i even tried energy saver 7w but
    i keep on changing, kindly what could be problem?

    /

  5. I am having these same issues...and others with my electrical in my new house. Bulbs heat up to ungodly levels almost instantaneously. It is not limited to one or two areas. It has totally blown out the light kit in a fan. Many bulbs have gone out quickly including range light, flood light, fan lights, ceiling lights. It's all over the house. Plus now when I turn on my porchlight it immediately turns off but turns on and stays on after a couple of tries. Electrician has no clue what is going on. Very disturbing.

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