How to Install a Light Dimmer Switch

Installing a light dimmer switch is a relatively straight forward project to do, however when dealing with electricity safety needs to be the top priority. You can replace a standard light switch with a light dimmer switch in less than an hour using just a common screwdriver and a pair of Needle Nose Pliers. Installing a Light Dimmer Switch Instructions To begin with, turn power off to the light switch at the main circuit panel or fuse box. Note, it is best to use only one hand when turning on and off the circuit breaker.

Your other hand should not be touching the circuit panel or anything that could come in contact with the ground.

Make sure you let everyone in the home know that you are working on the light switch and that for no reason should they turn power back on at the main circuit panel or fuse box. You may also consider putting a piece of tape over the circuit breaker and label it “DO NOT TURN ON”.

Remove old Light Switch After turning power off at the circuit panel or fuse box, toggle the light switch a couple of times to ensure that the light switch is no longer operational. Next, using your screwdriver, remove the screws that hold the light switch faceplate and pull the face plate off. With the faceplate off, and using a volt meter or neon tester, touch one probe to one of the switch terminals and the other to the ground terminal and see if you get a deflection on the volt meter or the neon tester glows. Repeat the test on the other switch terminals.

If the volt meter does not deflect or the neon tester does not glow in any of the tests then proceed forward. If you do see a deflection in the volt meter or the neon tester does glow then power is not off at the switch. Go back to the electrical panel and check to see what other circuit breakers could be feeding the light switch. NOTE: Make sure you have the volt meter set for reading 120VAC in order to use it properly.

Now remove the two screws that hold the light switch to the electrical box.

Next, pull the switch out from the electrical box a few inches.

Using your screwdriver and/or needle nose pliers remove the wires from the light switch and straighten them with your needle nose pliers

Buy a Light Dimmer Switch Visit your local home improvement store with your light switch in hand, and find a light dimmer switch to replace it with. You may want to ask a salesperson to help you find a functionally equivalent light dimmer switch. For example, if your old light switch is a Single Pole, Single Throw (SPST) type, you will need to find a replacement dimmer switch that is functionally the same. Install Light Dimmer Switch If you are installing a light dimmer switch that has only two black wires and a ground, simply install the light dimmer switch by connecting the two black wires on the light dimmer switch to the wires in the electrical box and according to the manufacturer’s directions.

Note that a 2 black wire dimmer switch does not have a polarity so it does not matter which black dimmer wire attaches to which light switch wire.

Connect the wires by twisting each pair together and then installing a wire nut over them. You may also want to wrap the wire nut with a small piece of electricians tape for added protection.

Also, if the light dimmer switch has a green wire, connect this wire to the ground wire in the electrical box.

If you are installing a light dimmer switch that has black and red wires and a ground, connect the black wire to the power (Line) and the red wire to the (Load). To determine which is which, pull out both switch wires from the box and separate them. Also pull out the bare wires (grounds) if the light dimmer switch is installed in a plastic electrical box.

Safety Notice on Installing Light Dimmer Switch

Being extremely careful and ensuring the wires are separated from each other, have someone turn on the circuit breaker. Using a volt meter or neon tester, probe one switch wire and the bare wire (ground), and see if you get a deflection on the volt meter or if the neon tester glows. If you do, then this is the Line and the other wire is the Load. Be careful not to touch the bare wires with your body.

If the electrical box is metal, probe one switch wire and the metal box, and see if you get a deflection on the volt meter or if the neon tester glows. Again, if you do, then this is the Line wire and the other wire is the Load.

Now have someone turn off the circuit breaker before proceeding further and connecting the dimmer switch wires to the Line and Load wires.

Connect the light dimmer switch wires by twisting each pair together and then installing a wire nut over them. You may also want to wrap the wire nut with a small piece of electricians tape for added protection.

Push the newly wired light dimmer switch into the electrical box and attach it with the two mounting screws.

Reinstall the new light dimmer switch faceplate cover that should have come with the dimmer and you are ready to test it.

Turn the power back on to your new light dimmer switch at the main circuit panel or fuse box.

Toggle the light dimmer switch and confirm the light turns on and off properly.

Adjust the dimmer knob or bar to confirm the light switch dims properly and you’re done.