Troubleshooting a Faulty Light Switch

March 9, 2022

Do you have a light switch in your home that isn’t working properly? If you have a screwdriver, voltage tester, insulated pliers and a wire connector you can troubleshoot your light switch to determine the problem and, if necessary, replace the switch. Light switches are inexpensive, and take only a small amount of time to replace.

Exercise caution when working with light switches, they can be very dangerous. If you’re not comfortable working with electricity, contact a professional electrician. Never work with electrical outlets, switches or fixtures, unless you have an understanding of electrical circuits and basic home wiring.

A light switch has small parts entirely contained inside a plastic casing, so if the switch is bad the best option is to replace it. But before you replace it you need to determine whether it is the light switch that is faulty or if the wiring is the problem.

Diagnosing Light Switch Problems

If the light switch isn’t working at all, there may be no power to the circuit. Make sure the breaker to the switch is on in your breaker box and determine whether there are any other tripped outlets and switch them on as well. This is the simplest solution you’ll want to try first that may fix the issue. If everything checks out, you may have a bad switch or faulty wiring at the connection.

If the light had been flickering, you’ll probably need to go a bit further. The problem may be a loose connection or a tripped wall outlet on the same circuit. The first thing you’ll need to do is turn off power to the light switch before handling it.

When you’re sure the breaker is off, remove the cover plate and unscrew the switch. With your insulated pliers, pull the switch out of the electrical box making sure to keep your hands and tools and other objects are well clear of the terminals.

Use a voltage tester to see if the terminals are receiving power. First, make sure your voltage tester is working by inserting the leads into a working outlet to verify that it’s getting a reading. If it’s working, test the switch by touching a lead from the voltage tester to the green ground screw and the other lead to a brass terminal. If the light stays off or the meter reads zero, move the lead to the other brass terminal. If you still get no reading, it’s safe to handle the switch.

Pull on the black wires coming from the switch to determine if they are tightly connected. If one is loose, tighten down its terminal screw until it’s secure. Then screw the switch back into the electrical box and turn on the breaker to test it. If the light works, screw the cover plate back in place and you’re done.

NOTE: If the wires were indeed loose, inspect the switch to determine whether it shows signs of melted plastic. If this is the case, you’ll also need to replace the switch because it has been damaged by electric arcing.

If neither of the black wires were loose, follow the steps to disable power to the switch again. Then disconnect both wires from the switch and twist them together with your pliers and screw on your wire connector. Switch on the breaker and if the light now comes on, you likely have a bad switch and need to replace it.

If the light still flickers or doesn’t come on when you bypass the switch, the problem could be a loose connection somewhere else in the circuit and you’ll either have to do further investigating where the light fixture connect to the circuit or call an expert to diagnose the issue.

Resources found on this site are provided as general information, and Reddi Industries does not assume any liability issues related to content provided here. We try to provide current/accurate information, but this article could contain info that is not correct for your situation. If you attempt to repair or modify equipment in your home or business, only do so if you are qualified.