Troubleshooting a Failing Light: An Electrician’s Guide

Do you have a light that just stopped working? It turned on yesterday, and now, nothing? As an electrician, I’ve spent lots of time troubleshooting lights. Below, I’ll walk you through common problems that you can investigate yourself, as long as you’re careful and approach the problem methodically. Just remember that electricity is dangerous, so don’t hesitate to call in a pro if needed. Your safety is most important.

Why Isn’t My Light Working?

Depending on your comfort level, troubleshooting a light can involve many things, from simple fixes to “calling an electrician. ” Here’s what to look for, followed by some steps to remedy the situation.

• Old, loose or bad bulb
• Tripped breaker
• Incompatible dimmer and bulb
• Bad switch (or loose wiring at switch)
• Loose wiring at light, or if lights are wired in series, another light on the same circuit
• Overheating around light (if equipped with thermal protector)
• Wiring problems elsewhere in the circuit

How To Troubleshoot and Fix a Light

Lights that don’t work are frustrating. Often, though, they’re a simple fix. You won’t know exactly why your light isn’t working unless you dig in and check. For these troubleshooting steps, you’ll need a non-contact voltage tester and a multimeter.

Check the bulb

Let’s start with an easy one. If you have a problem with a single light or fixture, the first thing to do is check the bulb. If it feels loose, tighten it. If it’s burned out, replace it. Check that the bulb’s wattage doesn’t exceed the max allowable on the fixture, which can cause overheating. (If the bulb is hot to the touch, let it cool down first.)

If it’s a fluorescent fixture, it might be time to replace the tube or CFL (compact fluorescent lamp) with an energy-efficient light-emitting diode (LED). Fluorescents tend to flicker when they reach the end of their lifespan, but they also flicker as they warm up in cold environments, so make sure the problem persists before rushing out to replace it. (Although any time is a good time to switch to LEDs.)

Verify the breaker didn’t trip

If it’s not the bulb, check the breaker. This is more likely to be the culprit if you notice all your lights not working rather than a single fixture, but it’s still one thing you can check off your list. If your breakers aren’t labeled very well, look for a breaker that is in a different (middle) position than the others. Flip it off, then on, and check your lights.

Check dimmer compatibility

Did you recently install a dimmer switch or swap out an old can light trim with a new one? Not all LEDs are compatible with dimmers, and not all fixtures are dimmable. If you still have the packaging, check to see if it specifically says “dimmable.” Most of the time, dimmer incompatibility will cause your light to drop out or flicker, but it’s possible it could stop working completely. If it’s not compatible, swap out the bulb or trim.

Look at the switch

If you feel confident, look inside the switch box to see if the switch terminations are tight and that all splices are secure. Always turn off the breaker and verify the circuit is off with a non-contact voltage tester. Remember that just turning a switch off does not cut power to the box or switch.

Switches have contacts inside that can wear out after hundreds or thousands of throws. If the switch movement feels loose or you hear a loud snap or buzz when operating it, the switch might be bad. Basic toggle switches are cheap, so it’s easy to just replace it as a troubleshooting step.

Test the switch for continuity

If you have a multimeter, test the switch before swapping it out. Continuity means that the current (when it’s on) has a complete, unbroken path through the switch. It’s important to turn off the breaker for this step, and verify the power is off. Never test continuity on a live circuit.

Set the meter to continuity or the lowest resistance (ohms) setting. Hold one lead to each of the brass screw terminals on the switch. If the switch is good, you should hear a beep when you toggle the switch to on and the resistance should be very close to zero. Your multimeter instructions can help you with settings and procedures, too.

Check the lights

Bad splices at the light can keep your light from turning on. Turn off the switch and the breaker, and be ready to verify with your non-contact voltage tester. You may need a helper, especially if the light’s on the ceiling. Carefully open up the fixture or remove it from the box, and verify all circuits are dead. Two hots can share a neutral, so it’s important to turn off all circuits.

Check the splices and connections to the light. Everything should be tight and secure. If multiple lights are out, the problem is likely in the first light after the switch. Check that one first (if you know which one it is.)

Replace can light

Canister lights, aka can lights, recess into your ceiling, so they have thermal protectors to shut them off if they get too hot. This could happen if insulation is packed too tightly around the light, or falls over it when someone traipses around in the attic. Or, maybe the wattage of the lamp is too high for the fixture.

If your light goes off for a while, then comes back on, the thermal protector might be sensing a problem with heat buildup. If the problem is obvious, like too much insulation covering the light, fix that situation first. Then weigh your options. You may have to call an electrician if the situation keeps happening, or replace the can if you’re comfortable. Never bypass a thermal protector or remove it entirely.

Investigate wiring problems

Wiring problems at your electrical panel, or somewhere between your panel and your switch or the switch and the light, could cause lights to not work. This is where it’s best to call an electrician unless you have a lot of knowledge about how your wiring works and where things are fed from. Check the basics first, then call a pro if you can’t figure it out.