My incandescent bulbs have been failing earlier than the specified life. Why is this?

Incandescent lamp life can be shortened by vibration or shock and supply voltage swings. If a lightbulb is going to be in an environment where it is exposed to vibration or shock, such as a garage door opener light or ceiling fan, you should try to use a lamp with a stronger filament. GE manufactures lamps specifically for these two applications along with the Survivor vibration-resistant and “Ruff-n-Tuff” rough service lamp.

Another cause of general incandescent lamp failure (other than leaving them on all the time) is high voltage. While utilities usually do a pretty good job of voltage regulation, they sometimes have little control. State regulatory boards allow them certain specified leeway because of anticipated load, local load peaks, and other criteria. The allowable limits are usually in the order of ten percent, which on your nominal house voltage of 230 volts would allow a range from 210 to 260.

Incandescent lamps are very sensitive to voltage. A lamp rated at 230 volts, for example, would only last 1/2 of rated life if subjected to 250 volts, or 1/3 of rating if the average voltage applied were 260 volts.

The first thing you should do is to keep track of how long the worst offenders are lasting. How long are your lamps burning? Be sure not to count the time that they are turned off. Typical incandescent bulbs are rated at 750-1000 hours, meaning approximately 2-1/2 changes per year.

The next step may not be easy. The only way to tell what average voltage your bulbs are experiencing is to attach a recording voltmeter to the circuit you are testing so that it records only when your lights are on. This step should only be accomplished by a licensed electrician. If you determine that you are receiving higher than rated voltage you will need to contact your electric utility to fix it.