How to Wire a Light Switch Safely

Gather Materials

There’s not too much prep work involved in this DIY since it’s a relatively simple project. However, there are a few things to keep in mind to make sure you work safely with electrical systems.

First, ensure you’re always wearing the proper safety equipment while working. You should have on rubber electrical gloves and rubber-soled shoes at all times. Rubber is an insulator, which means that if electricity does happen to jump out at you, it won’t be able to pass through your rubber safety equipment. Water and other liquids, on the other hand, are conductors and should be kept safely away from your work area.

Turn Off the Power at the Breaker

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Before beginning any electrical work, it’s essential to turn off the power at the circuit breaker box. If you’re unsure which breaker leads to the light switch you’re working on, test each breaker by turning the switches on and off until you find the match.

It’s important to note that sometimes the breakers can be mislabeled, so even if the room is labeled on the panel, testing the light switch is a good idea as an added safety precaution.

Remove the Switch Plate and Light Switch

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Remove the switch plate by taking out the screws with a flathead or Phillips-head screwdriver (most are attached with flathead screws). Set the switch plate and the screws aside if you plan to reuse them. 

To be extra cautious, use a multimeter around the exposed switch to ensure there isn’t any live voltage. Once you’re certain there’s no current, you can remove the screws to the light switch with the corresponding screwdriver. Then, gently pull out the existing switch, leaving the wires attached.

Identify and Disconnect the Wires

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Before you disconnect the wires, it’s helpful to identify the electrical wires by their color codes. Here are the main points to know about the colors of wires when you’re wiring a light switch:

• Black wire: The black wire (sometimes red) is the load or hot wire that carries the voltage through the switch. In a light switch, the black wires connect to the brass screws on the side of the switch, which are known as terminal screws.

• White wire: The white wire is the neutral wire, and it’s sometimes connected to another white wire covered by a wire nut. 

• Copper wire: The bare copper wire is considered the ground wire. It can also be green or green with a yellow stripe. In the switch, the ground wire is attached to the green grounding screw.

Loosen the screws holding the black, neutral, and ground wires in place with a screwdriver, pulling away the old switch and discarding it. You may need to free the wires with needle-nose pliers if the coil is too tight.

Inspect and Prepare the Wires

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Check over the ends of the wires for fraying or shredding. If you locate any issues, trim away the damaged ends using wire cutters or a multi-tool. This is an important step, as you want to ensure that any part of the wire that’s touching the screws is in good condition.

Using a pair of wire strippers, remove half an inch of wire insulation, leaving that much wire exposed. Then, bend the exposed wire into a “U” shape so that it can be positioned around the screw in a clockwise direction.

Wire the Switch

Start by wrapping the exposed portions of the black wire and white wire around the brass terminal screws on the right side of the switch in a clockwise motion. It doesn’t matter which one goes on the top screw and which one goes on the bottom. With your screwdriver, tighten the screws in a clockwise direction to secure the wires into place. 

Repeat this process with the copper or green wire, attaching it to the copper or green screw on the lower left side, also called the ground terminal. If you’re installing a double or three-way light switch, make sure to wire to each terminal.

Note: It can be helpful to use needle-nose pliers to hold the wires in place, but it’s not necessary to connect the switches.

Attach the Light Switch

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Once you’ve connected all the switch wiring, you can reassemble the parts.

Wrap the switch and terminal screws with electrical tape to prevent any arcing in the electrical box, which occurs when an electrical current jumps from one connection to the next. Then, neatly and gently tuck the wires into the switch box and screw the new switch into place with a screwdriver.

Test the Switch and Attach the Cover Plate

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Turn the breaker back on and flip the switch. At this point, the light should turn on. If it doesn’t, there may be a loose or incorrect connection.

To fix a loose connection, turn off power at the breaker box and unscrew the light switch. Then, check each screw to ensure you’ve tightly wrapped the wires around them and that the screws are secured firmly into place. Once you’ve done that, screw on the light switch, turn the breaker back on, and flip the switch again. If the light works, you can re-attach the switch plate or install a new one using a screwdriver.

If the light still isn’t working, you should call an electrician to diagnose the problem.