The light fixtures in our homes are remarkably effective and may work for years with little attention other than replacing an occasional burned-out light bulb. Sometimes, though, a light fixture that's been working fine may suddenly develop a problem that requires diagnosis and repair. The correction can be very simple—such as replacing the light bulb or adjusting the light bulb socket—or as complex as replacing the entire light fixture or a wall switch. The first step, though, is to diagnose the problem. How you do this will depend somewhat on the type of light fixture and the symptoms you observe.
Always turn off power to the circuit from the circuit breaker box before touching a bare lightbulb socket.
Common Problems With Ceiling Light Fixtures Controlled by Wall Switches
Apparent problems with a ceiling light fixture are usually traced to some issue that is interrupting the flow of electricity from the wall switch to the light fixture. Diagnosing the problem will depend on whether the light bulb does not light up at all, or if it is flickering intermittently.
If the light bulb does not light up at all, follow this troubleshooting procedure:
- Check the light bulb first to see if it has burned out. If so, replace the bulb.
- Check to see if the bulb is tight in the socket. The constant on-off flow of electricity can sometimes loosen a light bulb in the socket. Simply screwing in tighter will fix the problem.
- Check the metal socket tab in the bottom center of the socket. If it has become flattened, you may have to bend it back up slightly in order for it to make contact with the bulb.
- Check the connections at the switch and make sure that they are tight. Be sure that the power is off to the circuit that you are working on.
- With the power shut off, check the wire connections at the light fixture and at the breaker panel to make sure they are all connected tightly. If you have concerns about these connections, you may want to have these examined by a qualified electrician. Unless you are very experienced at electrical work, do not tamper with connections in the circuit breaker panel.
If the lightbulb flickers, follow this troubleshooting procedure:
- If the bulb flickers on and off, it usually means that the switch contacts are getting bad. Usually, you'll be able to hear a sizzling or crackling sound if the switch contacts are bad. In this case, replace the switch.
- It also could be that the wire connections are loose. This could be on the switch itself, at the circuit breaker panel, or in a pass-through wire connection in the wall box or ceiling box. By far the most common problem is a loose wire connection at the switch itself, which is subject to constant on-off usage.
- Less commonly, a light bulb socket may go bad. If so, you will need to replace the socket.
Common Problems With Recessed Lights (Can Lights)
Recessed canister lights are subject to some of the same problems found in ordinary ceiling light fixtures (see above). In addition, sometimes a recessed light fixture may mysteriously go on and of by itself. This is because recessed lights are equipped with limit switches designed to turn a fixture off automatically if the heat reaches an unsafe level. This can be for one of several reasons:
- Check to see if the lightbulbs in the light fixture have the proper wattage for the light fixture. If the wattage is too high, it may be causing the fixture to overheat. Compare the wattage on the light bulb with the rating printed on the light fixture. Install a lower-wattage lightbulb, if necessary.
- If insulation is packed too tightly around the light fixture, it may be trapping heat around the light fixture canister, causing the limit switch to overheat and shut down the light fixture. Make sure there is enough air circulation around the canister, which will prevent the fixture from overheating.
- The limit switch may be faulty. If the light bulb wattage is correct and there seems to be proper ventilation around the light fixture, then consider replacing the limit switch or the entire light fixture.
Problems With Integral Switches or Pull Chains
Many ceiling fixtures, especially those found in utility spaces, are controlled by switches or pull chains found on the fixture or socket. To diagnose these:
- Check the lightbulb to see if it is loose in the socket, or has burned out. Tighten the bulb or replace it, as needed.
- Check the socket tab in the center of the socket. If it's flattened, you may have to pull up on it in order for it to make contact with the bulb. Shut off power to the circuit before touching a bare metal light socket.
- With the power shut off, check the wire connections on the switch to make sure they are all tight. Remove the switch from the circuit and test between the wires with a continuity tester or with an ohm meter.
- Check the wires to the light bulb socket. If they are loose or have a burnt appearance, replace the socket.
Recessed light fixtures: infiltration energy loss. ASHRAE Journal. (1994) 36(6), 82-90.