Installing a dimmer switch? [How to, Wiring, Replacing] Guide

You got a new dimmer and now you`re not quite sure how to wire a dimmer switch?


Let`s go over the basics in this article, so you can easily install your dimmer.

What tools do you need to install a dimmer?

You don`t want to hurt yourself while installing, that`s why a voltage tester is always good to have available.

Voltage tester




Wire strippers


Wire nuts

Wiring a dimmer light switch

How to replace a light switch with a dimmer?

Let`s get started:

Any switch, that controls a light, can be replaced with a dimmer.
how to wire a dimmer switch
You will need a special dimmer to control a fluorescent light or a fan, but when you come right down to it, a dimmer is just another switch. The major difference is that instead of terminal screws the dimmer has wires coming out of it.
Start the job the way you start any electrical job, turn off the power at the fuse or breaker box.
how to wire a dimmer switch
how to wire a dimmer switch
Double-check, by testing the wires for power, before you do any work.
Slip the probes of a neon voltage tester against switch terminals, if the tester lights, the circuit is still hot.
Try shutting off another circuit and don’t start working until the light tells you the power is off.
how to wire a dimmer switch take out the old switch
When you are sure the power is off, remove the switch, which can be either a regular switch or a dimmer that needs replacing.
remove the wires from the switch
Remove the wires connected to the switch or dimmer,
cutting the loops off the wires
if there are loops at the ends of the wires, cut them off and
strip one inch off the insulation
strip off about an inch of insulation.
strip the dimmer wires
Strip the dimmer wires as needed, to expose about an inch of wire.
connecting both the cables bare ground wire and the dimmers green wire to the box
If the switch box is metal, you’ll start by connecting both the cables bare ground wire and the dimmers green wire to the box.
making a ground wire to dimmer
If there isn’t already a ground wire running to the box, make one from a piece of scrap cable.
Get a pack of ground screws,
putting the ground wire in the box
 attach a ground wire
put one in a threaded hole in the box and attach a ground wire.
Twist the solid ground wires together tight
wrapped wires clockwise
Twist the solid ground wires together, wrapping them clockwise,
roll the strand dimmer wires together tight
roll the strands of the dimmer ground wire together and
wrap it around the ground wire
then wrap it around the two solid wires.
wrap the stranded wire around the solid wires
Wrap it, so that about one-eighth of an inch of the stranded wire, extends beyond the ends of the solid wire.
wrapping with a wire nut
Cover all three with a wire nut and turn it clockwise.
The extra one-eighth of an inch of stranded wire, helps keep the stranded wire in place while you tighten it.
dimmer wiring in a plastic box
If the box is plastic, you can connect the dimmer and cable ground wires to each other without connecting them to the box.
wrap dimmer wire around black or brown wire
Once you have installed the ground wire, wrap one of the remaining dimmer wires around either the black or white cable wire,
wire in nut and tight twist
once again letting the dimmer wire extend beyond the cable, by about one-eighth of an inch. Slip-on a wire nut and twist until tight.
red wire nuts and dimmer switch
Repeat with the last two wires, cover them with a cap, and twist until tight. Tug gently on all wire nuts, to make sure they are firmly attached, fold the wires into the box and
screw the dimmer in place
screw the dimmer and cover plate in place.

It not harder than this to replace a light switch and wire a dimmer switch

If the dimmer is replacing a three-way switch, replace it with a three-way dimmer.

screw the dimmer in place
When you remove the existing switch, label the wire that’s attached to the common terminal, the screw it’s on will be a different color than the others.
clipping the loops wires
Clip the loops off the ends of the cable wires, strip an inch of insulation off each of the clipped wires.
common wire wiring three way dimmer
When you wire the new dimmer, connect the wire you labeled it to the common wire, on the dimmer, and cap with a wire nut.
Connect either one of the remaining dimmer wires, to either one of the remaining cable wires and put on a wire nut. Connect the remaining two wires together and cap with a wire nut.
replacing three way dimmer with a new three way dimmer mark the wires
If you’re replacing a three-way dimmer with another three-way dimmer, label the cable wires as you remove them, so you can connect the new dimmer the same way the old one was connected.

If wiring a dimmer switch is too difficult for you, remember there is no shame in getting an electrician to do the job.


Can I install a dimmer switch on any light?


Replacing a regular single-pole or three-way switch with a dimmer switch is no different than substituting a standard switch.

Remember this, dimmer switches don’t work on most fluorescent fixtures, and low-voltage lighting needs special low-voltage dimmers.


Does it matter which wire goes where on a dimmer switch?


Unless the new dimmer is clearly labeled with LINE and LOAD or related, it doesn’t matter which wire goes to which screw.


Does a fixture have to be dimmable or just the bulb?


Most light fixtures will work with regular dimmer switches, including those with halogen and incandescent lamps.

If you are dimming a LED bulb, make sure it’s dimmable because, if you don’t use a dimmable bulb, you can get buzzing, flickering, and other kinds of problems.