4 Reasons Light Bulb Not Turning Off (Fixed!)

light bulb not turning off

This paper from Indiana University Bloomington agrees that turning the lights off is the best way to conserve energy. But what if a light bulb refuses to turn off? The guide below will tell you what to do.

Don’t ignore a light bulb that won’t turn off. Some of the factors that prevent the bulb from turning off are dangerous. They can lead to arcing, fires, and deadly shocks. You can blame a bulb that won’t turn off on the following:

1). Are You Sure The Light Has Refused To Turn OFF? Or Is The Bulb Glowing Dimly?

You see this in LEDs. They will technically turn off. But then a closer look will reveal a dim glow, which you can ignore unless the light is situated in your bedroom. A glowing LED can keep you awake. LED bulbs can glow because of the following:

  • You have a low-quality LED that flickers and glows even when you flip the switch to the off position.
  • Your lamp has a luminescent layer that stores energy for a specific duration. This can produce an afterglow lasting seconds or several minutes, depending on the quality of the light.
  • A circuit called an LED driver stores electrical energy. That stored energy generates a temporary glow when the input voltage disappears.
  • You will see a glowing LED on a current leak and induced voltages. You see this when you replace old bulbs with LEDs.
  • Look for dimmer switches, the kind that works with incandescent lamps. The switch continuously passes small volumes of electricity through the filament. This is not enough to illuminate the incandescent lamp. However, the LED is so efficient those tiny currents are enough to generate visible light.

2). The Switch Is Faulty

The light switch can fail. For instance, it can stick in the closed position because of a burnt or loose internal spring, forcing the contacts to touch. You can also weld the contacts and pins together by repeatedly forcing the device to switch higher loads.

3). You Wired The Light/Switch Poorly

Lights are simple devices. However, the installation process can take a complicated turn, especially for switches in the middle of a circuit. You may also encounter this issue when one switch controls multiple lights.

For all you know, the wire running to the light is touching a live conductor, or power is coming to the light via a different wire you’ve yet to identify.

4). The Light Keeps Turning On And Off

Maybe you thought you turned the light off when, in truth, the light switched itself off, and then it came on later, which created confusion. People expect bulbs to flicker rapidly when things go wrong, but they can turn off for several seconds or even minutes before turning back on.

This can happen for various reasons, including surges originating from large appliances as they cycle on and malfunctions on the grid, faults in the bulb, bad weather, loose connections, etc. Lights that turn on and off should concern you because the symptom can point to arcing.

How Do You Fix A Light That Won’t Turn Off?

It depends on the reason why the light won’t turn off. Start by checking and testing the switch:

  • De-energize the circuit.
  • Remove the cover.
  • Take the switch out of its box.
  • Disconnect a wire and cover the bare end with tape. Make sure the switch is far enough from the box that the pins cannot touch.
  • Cover the switch pins with tape.
  • Energize the circuit.
  • If the light stays off, the switch has a problem. But if the light comes on, the problem lies elsewhere.

If you trust the switch, check the wiring. You probably made a mistake somewhere during installation. Try to tick the following boxes:

  • Splice the neutral wires together. Don’t connect them to the switch.
  • Twist all the ground wires together and connect them to the ground screw.
  • Run the live wires to the brass terminals.

These are the most basic requirements for installing a switch. Make sure you connect each wire to the correct terminal. Don’t wrap the ground wires around the brass screw and the live wires around the neutral terminal.

If the wires are a mess, use the colors to identify and label them. If you don’t recognize the wires, check them with a voltage tester. If you can identify the extra wire bringing power to the light fixture, you can disconnect it.

You can apply that same voltage tester (with two leads, not the non-contact model) to the switch. Touch the tester’s leads to the brass terminals. Do this when the switch is on. Did the tester’s LED illuminate?

Repeat this test with the switch turned off. Did the tester’s LED go off? If it did, the switch is fine, and the wiring is the problem. But if the LED stays illuminated, you have a bad switch.

Don’t forget to troubleshoot the light fixture. You can apply one or more of the following solutions depending on the observations you make:

1). If you have an LED bulb and it tends to glow after you switch it off, test the bulb by removing it from the socket immediately after flipping the switch to the off position. If the glow persists, the fault lies with the LED. The bulb is storing energy. This is inconvenient but not necessarily a cause for concern

But if the glow disappears the moment you remove the bulb from the socket, you have a wiring problem. Troubleshoot the wiring behind the switch and light fixture.

2). You can wait for an LED’s afterglow to dissipate gradually. This glow is annoying, but it should disappear after a while. If the glow lasts longer than you would like, replace the bulb. Buy a more expensive, higher-quality alternative that doesn’t glow.

3). Replace dimmers with conventional switches. It is worth noting that many LED lamps cannot provide the minimum load some electronic dimmers require to turn the output voltage off completely. As a result, the LED bulb will glow.

You can solve this problem by replacing the electronic dimmer with an LED dimmer. Take this step after comparing the old dimmer’s minimum load with the LED lights. You don’t want to waste money on a new dimmer when the problem lies elsewhere.

4). If you have a defective switch, replace it. Switches are too cheap for you to fix a bad one. You are better off getting a replacement. While a layperson can replace a conventional switch if they have some DIY experience, you need an expert’s assistance to troubleshoot 3-way and 4-way configurations.

A layperson is unlikely to identify the defective switch. An expert can also troubleshoot the bulb. Have you checked the light fixture? Are the contacts okay? What about the wiring behind the socket? This process is somewhat complicated unless you know what to look for.

Like the switch, don’t hesitate to replace a faulty socket and light fixture, especially if the problem doesn’t originate from poor wiring.

5). If the light is turning on and off because of a malfunction on the grid, call your utility provider.

If you can’t identify the problem, use the breaker to kill the power in the room with the light bulb that won’t turn off. This will save energy while you wait for the electrician to arrive.

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