This article comes from The Spruce.
Light bulbs can’t burn forever, and 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.
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.
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.
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.
Although they have a reputation for lasting longer than incandescent bulbs, compact fluorescent (CFL) light 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, last longer, and they don’t contain mercury like CFL bulbs do.
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.
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.
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