We all wish light bulbs could burn forever, but in reality, incandescent bulbs have a lifespan of around 900 hours. Based on a usage of eight hours a day, a bulb should last roughly about four months. Compact fluorescent bulbs (CFLs) are supposed to last much longer, but this is not always the case. If you have replaced bulbs recently and the lifespan doesn't seem to be all that it should, the cause may be in the fixture itself or elsewhere in the circuit.
01 of 09
High Voltage in the Home
If the supply voltage to your home is too great, bulbs will generally burn brighter and burn out much faster. You can test for voltage at a standard (120-volt) electrical outlet, using a multimeter or a voltage tester; be sure you know how to do this safely because the power will be on. If a test reveals a voltage higher than 125 volts, have an electrician take a look at the problem, or contact your electric utility provider for recommendations.
02 of 09
Excessive Fixture Vibration
Another cause of bulbs burning out is excessive fixture vibration. A good example of this is a ceiling fan with a light fixture. When a fan blade becomes unbalanced, the fan starts to shake, and the vibration jiggles the filament in the bulb and shortens its life. The same problem is common with light bulbs in garage door openers. You can try a rough-service bulb to correct this problem. These bulbs have heavy-duty filaments to withstand vibration better.
03 of 09
Depressed Socket Tab
The little metal tab at the bottom of a light bulb socket is the "hot" connection that delivers electrical current to the bulb (the surrounding threaded metal is the neutral connection). If the socket tab in the bottom of the socket gets pushed down too far, it can fail to make contact with the bulb. The problem here is not that the bulb has burned out, but that it no longer makes electrical contact with the socket.
To remedy this, unplug the lamp or turn off the power to the fixture, then use a wooden popsicle stick to bend the tab up about 1/8 inch. Then screw the bulb back in and see if it works.
This repair may not be possible with old sockets, where the metal tab is brittle or has lost is spring entirely. In this case, the best solution is to replace the light bulb socket or the entire light fixture.
04 of 09
Wrong Type of Bulb
Although they have a reputation for lasting longer than incandescent bulbs, compact fluorescent (CFL) ligh bulbs are notorious for going bad before their time. CLFs are commonly touted to have a lifespan of about 10,000 hours, but if you've owned some of these, you know that this number is grossly exaggerated in many cases. The lifespan of CFL bulbs will also shorten if the light fixture is switched on and off too often. A bulb rated for 10,000 hours might last only 3,000 hours if it is switched on and off many times of day for a few minutes each time.
The answer: Switch to LED (light-emitting diode) bulbs. They're more efficient, they last longer, and they don't contain mercury, like CFL bulbs do.Continue to 5 of 9 below.
05 of 09
When a bulb is loose in the socket, it can flicker on and off. Simply tighten the bulb in its socket to correct the problem. Another issue may be a loose wire connections where the circuit wires connect to the fixture. Turn off the power and check the wires to make they are securely attached to the screw terminals. The bulb socket itself can also have worn or corrode contacts that cause connection problems. In this case, replace the socket or the fixture.
Habitually loose connections, either at the socket or with the wire connections, can burn out the bulb quickly, as well as cause flickering. These loose connections increase the electrical resistance and the heat passing through the filament of the bulb, which can shorten its life.
06 of 09
This is another instance where a light bulb that suddenly goes dark is not burned out at all. A short circuit in the wiring of the circuit can cause the light fixture—well as all other devices on the circuit—to suddenly go dark. The official definition of a short circuit is a condition in which the electrical current flows outside the established wiring pathway. This situation causes resistance to lessen, which vastly increases the flow of current through the circuit. This sudden increase in current flow causes the circuit breaker to trip (or the fuse to blow) and stop the flow of current. The lightbulb (and everything else) suddenly goes dark.
A short circuit can be caused by a number of circumstances. The fixture or appliance cord may have wiring problem, a cord plug could be defective, or the light socket may be defective. In any of these cases, replace the defective parts before resetting the breaker or replacing a fuse.
Before assuming that a dark bulb is a burned-out bulb, check to make sure that the circuit breaker hasn't tripped due to a short circuit.
07 of 09
Bulbs Too Large for Light Fixture
Most light fixtures have a label stating the maximum bulb wattage to use in the fixture. If you find that lightbulbs burn out to quickly in a particular lamp or light fixture, open the fixture globe or cover and check to see if the bulb wattage is too large for the rating of the fixture. This isn't a likely problem with CFL or LED bulbs, which operate at fairly low wattage, but it is a very common problem with traditional incandescent light bulbs, where it is easy to exceed the rating of the light fixture by using lightbulbs that are too large. Doing so creates excessive heat, reducing the bulb life and potentially melting the insulation on the fixture wiring.
Prevent problems by using bulbs with wattage ratings that don't exceed the rating of the fixture. Changing to energy-efficient bulbs (such as LEDs) that have much lower wattage ratings will also prevent such problems in the future.
08 of 09
Insulation Around Recessed Lights
Recessed light fixtures (sometimes called "can lights") often have housings that extend into the attic. Some recessed light fixtures are designed to be covered with attic insulation, but on other older designs, the insulation must held back by at least 3 inches to prevent the fixture from overheating. Overheating can cause the fixture to shut off automatically, or it may cause the bulbs to flicker or burn out early. Overheated recessed lights can potentially lead to a fire. If your fixture is not rated "IC," it should not be covered with insulation.
You can build a box (chase) around the fixture housing to allow for the appropriate space around the fixture. Or, install a new IC-rated fixture that will tolerate contact with insulation.Continue to 9 of 9 below.
09 of 09
Wrong Type of Dimmer Switch
If lightbulbs in a fixture controlled by a dimmer switch burn out quickly, there is a good chance the wall switch uses the wrong kind of dimmer. Older dimmer switches were designed for use with standard incandescent bulbs only, and if you use CFL or LED bulbs in the light fixture, the standard dimmer may damage the circuitry in the bottom of the bulb and cause it to quickly burn out.
Fortunately, there are dimmer switches designed work with CFL or LED light bulbs, and replacing the old dimmer generally solves the problem.