Light up your DIY electrical skills
Although an electrical problem in your home is nothing to take lightly, if the trouble stems from a failed single-pole light switch, you can likely tackle the issue on your own. DIY light switch replacement on a simple electrical circuit can save you time and money. However, staying safe is the first priority. Learn how to install a light switch and discover when the task is possible versus when to call a pro.
We do not recommend DIYing any electrical project if you don’t have some electrical know-how before beginning. The safest course of action is always to hire a professional electrician to install or replace anything involving electricity in your home. However, if you’re an exceptionally handy DIYer with skills that would shock the average project-doer, this may be a perfect Saturday afternoon task.
Before diving into any home electrical project, take a few minutes to review electrical safety basics. First, always wear rubber electrical gloves to protect yourself from shock. The most important thing to remember is to avoid severe injury or house fires by never performing work on or touching exposed components of a live electrical circuit.
Always test the electrical circuit you're about to work on, even if you're confident that the power is off. Keep reading to learn how to operate whichever electrical tester you have on hand and how to test the tester before each use.
This specific guide includes steps for installing a single-pole light switch, which is a relatively simple device. These switches consist of a pair of electrical connection points or terminals, a grounding connection screw, a body and switch, usually a pair of push-in connection holes, and tabs with mounting screws. Did your eyes just glaze over? If so, you might want to let a professional tackle this one.
In a single-pole light switch configuration, the switch may be a large or small toggle or any type of dimmer switch. They all wire into a circuit similarly, except for smart switches, which require additional steps and more electrical knowledge than this project's scope.
Inside the switch is a mechanism that opens and closes the electrical circuit to turn off and on the light. One connected wire brings live current to the switch. Another carries the current to the light when the switch is closed or "turned on."
There are just a few things to consider when preparing to install a single-pole switch. The first is to be sure that you purchase the correct type of electrical switch. If the light controlled by the switch you're working on is also controllable by another switch in the room, the circuit is a three-way switch system and requires different wiring than a single-pole system.
At the store, buy a switch labeled as a single-pole switch. You can identify it by noticing that it has on and off indicators. In the case of a dimmer switch with a dial or slider, there may not be on and off indicators. You can look at the wire connections to determine what kind of switch it is.
A single-pole switch will only have two wire connection screws or wire leads on the side of the switch, plus a green wire connection screw or lead. The switch may also have two wire-sized holes on the back. Any switches you see on the store's shelves with more than these three connections are for a different kind of circuit.
You can use a regular screwdriver and a Phillips-head screwdriver for this project. However, for ease, you may consider purchasing a multi-bit screwdriver with a pair of square drive bits to better fit the screw terminals on the new switch.
Part of what makes learning electrical repair challenging is not knowing what’s waiting for you behind the cover. This can be further complicated for this project because light switches come in various styles and wiring configurations. When learning how to install a light switch, the first step is to identify what you might see when you open the switch cover. Here are a few examples:
Two black wires connected to the back or sides of the switch
An additional green or bare (copper) wire connected to the switch
Any combination of red, gray, or blue wires connected to the switch
Any combination of wire colors connected but not attached to the switch
Various wire nuts or connections
The only wires you should concern yourself with for this project are the two wires, regardless of color, connected to the switch terminals and the bare or green wire on the back of the switch. You can leave the rest, if there is anything else, alone.
If you're replacing a single-pole dimmer switch, it may have wire leads and wire nuts that connect to the house’s electrical system, but the concept is the same.
In older homes, you may see black wires that appear to have a cloth or paper-like covering. Finding these black wires means the switch is on a knob and tube (K&T) circuit. Knob and tube wiring was once standard but is now obsolete.
Although installing new K&T wiring is prohibited, having it in your home isn't necessarily dangerous unless someone has altered the wires in the past. However, if you find any K&T wiring, you should immediately call a professional to inspect your wiring before proceeding with this project.
Locate the breaker switch in your home's electrical panel for the lighting circuit you're working on and flip it to the off position. As a preliminary test, turn the wall switch on and ensure the light doesn't illuminate. If it does, try another breaker switch and test again until you find the correct one.
Use a regular screwdriver or multi-bit driver to remove the switch plate by twisting its visible screws counterclockwise. You may have to pry the plate from the wall lightly if it’s been the victim of overpainting.
While wearing your rubber electrical gloves, test your non-contact or probe-type voltage tester on an outlet you know is drawing power to ensure it's working before testing the switch you're replacing.
For a non-contact tester, place the device onto the face of any working light switch that’s turned on. For a probe-type tester, reach into the electrical box with the probes and contact each terminal. If your tester signals any voltage, you know it’s working. Now, you can test the switch you plan to replace. If you see your tester signaling voltage, return to the breaker box and find the culprit before proceeding.
Only after ensuring there's no electrical current present, twist the installation screws on the existing switch counterclockwise until the switch is free of the box. Gently pull the switch body out of its electrical box, stopping before you fully extend the wires.
Your switch will have three wires connected to it. If you only find two, the circuit may or may not lack a ground. In some cases, that's OK, but having an electrician take a look to determine its safety status before moving forward is the safest course of action.
In either case, inspect the wiring and how it's connected to the switch. It never hurts to take a photo for later reference. Disconnect the wires by loosening the terminal screws on the side of the switch. If the wire connections use the push-fitting holes, release them by inserting a small screwdriver into the slot next to each one and pulling the wires free, one at a time.
On many wall switches, you can use the screw terminals or the push fittings to connect the wires to the device. We recommend using the screw terminals, as experts consider push fittings less secure.
To prepare the wires for reinstallation, use the ends of your wire stripper or needle-nose pliers to shape the wire tips, including the ground wire, into a letter "c" shape. You may have to cut off damaged wire ends and strip off 1/2 inch of the casing before shaping them.
Wrap each hot (black) wire clockwise around one of the screw terminals that isn’t the ground screw (typically green), and tighten the connection with a Phillips-head or square screwdriver. It doesn't matter which circuit wire connects to which terminal.
Repeat with the ground wire, attaching it to the green screw terminal on the switch. Ensure the ground connection is still secure on its other end. It may connect with a wire nut in a pigtail configuration or to a screw on the metal electrical box. If this all sounds like barnyard talk to you, put down the screwdriver and call a pro.
Next, gently press the switch body back into the electrical box. Line up and turn the installation screws clockwise into the corresponding holes in the box until the switch body is secure.
Replace the switch cover over the new switch and twist its slotted screws clockwise until they're snug. Avoid over-tightening the screws to keep from damaging the cover plate.
Return to your circuit breaker box and turn the breaker switch on. Test the new wall switch and light to ensure they're working. If the light doesn't turn on, turn off the breaker again before double-checking your wiring connections at the wall switch. If you’ve double-checked your connections and your light still isn’t working, it’s time to let a certified electrician handle the task.
Now that you know how to install a light switch, think very carefully about if you should actually do it on your own.
DIY light switch installation isn't a physically demanding task. Performing the task yourself costs just a few dollars for the switch and possibly the cost of a new multi-bit driver. That can mean considerable savings over the cost of hiring an electrician to do the work. Having some electrical circuitry knowledge is definitely helpful, but if you don’t know the difference between a Phillips-head screwdriver and a flathead screwdriver, you should probably leave this one to the pros.
Additionally, if you're experiencing other electrical problems in your home, such as lights flickering when you operate the suspect switch or turn on appliances, skip the DIY and contact a local electrician to determine the root cause. Remember that you're not alone if performing electrical work makes you uncomfortable. It's better to be cautious, and we won't fault you for staying safe by hiring a professional.
Incorrectly wiring a single-pole switch results in the connected light or device not turning on or tripping the circuit breaker. Although it doesn't matter which terminal the hot wire and the load wire connect to, mixing up a circuit wire with a ground or having loose connections can prevent the switch from working.
There are several indicators that a single-pole switch is bad: the switch is warm or hot to the touch, sparks are sometimes present when turning the switch on or off, you hear a buzzing sound or other weird noise coming from the switch, the connected light flickers when you turn on the switch, and the light doesn't turn on at all with the switch. If you notice any of these, replace the switch or call a pro straight away.
Smart switches require a neutral wire for correct installation. Neutral wires aren't typically present in a single-pole switch configuration, so this project can be a tricky one for average DIYers. In most cases, you should hire an electrician to run a new circuit or adapt your existing wiring to include a neutral connection to accommodate a smart switch.
