How to install motion sensor light switch 3-way?

You’re sick of coming home to a dark house. Or maybe you want to deter burglars and make your home more secure. Whatever the reason, you’ve decided that you want to install a motion sensor light switch 3-way. But you’re not sure where to start.

Don’t worry, we’ll walk you through everything you need to know about installing a motion sensor light switch 3-way. We’ll go over what you need, the steps to take, and some tips to make sure everything goes smoothly.

So let’s get started!

What Is a Motion Sensor Light Switch?

What Is a Motion Sensor Light Switch?
What Is a Motion Sensor Light Switch?

Motion sensor switches have been around for a long time, but they have never really caught on in homes, even though they are often required in a commercial buildings. Simply put, this kind of switch will turn on the lights whenever it senses movement. There are times when motion sensor switches can be useful.

This article will show you how to install a motion sensor switch step-by-step, using photos of a laundry room that is getting a new switch. It’s not fun to walk into a dark room with two arms full of laundry, but the room was made for the job.

Picking a Motion Sensing Switch

The need for a neutral wire is the most important thing to think about. Some motion-sensing switches need a neutral (white) wire to work, while others don’t. For those that do, there is no other way to connect them.

So, before you go shopping for a switch, you should take out the one you have and check to see if there is a neutral wire in the electrical box. Remove the switch from the box by following the steps in the next section. Don’t take it out of the box, just pull it out far enough to see what’s behind it. You’re looking for a white wire that doesn’t go to the switch you already have.

In older ways of wiring, a white wire could be part of a switched circuit. The switch will be hooked up to this wire. If that’s the case, it’s not a neutral and can’t be used as one. Neutral wires will be one or more white wires that go through the box without ending at a switch.

Any motion switch can be used if there is a neutral wire in the box. If not, you need to make sure the switch you buy doesn’t need a neutral. Most motion switches, but not all, already have wires attached that will be joined to the ones in the box with wire nuts. If the switch has a white wire, you will also need a neutral.

You will also need to know if the old switch is a simple single pole (two wires plus ground) or a three-way switch (three wires plus ground), because the motion sensor switch will need to have the same setup. If the old switch has four wires and a ground, it can’t be replaced by a motion detector switch.

Other than these two things, motion switches are about how they look and what they can do. Some have a built-in dimmer (make sure your lamp can be dimmed), and most have a delay setting that can be very helpful.

  • A common switch with a motion sensor. There are three wires that are black, red, and green. A neutral wire is not needed.
  • The switch’s faceplate has been taken off, revealing an arrow-shaped knob on the left side that controls the time delay.
  • A motion switch with three positions. There must be three wires and a ground. Each corner has a terminal that the wires must be connected to.

First, safety!

Voltage detectors are cheap tools that everyone who works with electricity needs to have. They can tell if there is voltage through the insulation. They don’t need a bare wire to do this. As a professional electrician, I always have one in my pocket and use it before touching any wire that might be “hot.” If you do electrical work now or in the future, you might want to buy one of these voltage detectors that you don’t have to touch.

Taking Out the Old Switch

Now that you have the new motion sensor switch, you can get rid of the old one.

The first step is to turn off the power. When the light is on, turn off the breakers or pull out the fuses until the light goes out. If there is even a small chance that someone might turn the breaker back on (which would make more than just the room you are working in dark), tape the breaker off to show that there is a reason it is off.

Power outage warning
Power outage warning

The cover plate is held on by two screws, and the switch is held in place by two more screws. Carefully pull the switch out, holding it at the top and bottom where the screws were, just in case the power is still on (maybe the bulb burned out at the wrong time; don’t take the chance of getting shocked).

The cover plate
The cover plate

With the switch removed from the wall but the wires still connected, use a non-contact voltage detector or. voltmeter to make sure there is no power before going any further.


Depending on the kind of sensor switch you have, you might need to figure out which wire goes where. Someone brought up the possibility of a neutral wire; if the sensor switch needs a neutral, you should have already found it.

Installing the Motion Sensor Switch

Connect the ground wire in the box, which is green or has no insulation, to the green screw or wire on the new switch. If wire nuts are being used to connect the wires, like in the switch in the picture, screw the nut on and pull on each wire while holding the nut. It’s better that they break now than when you put the wires into the box and can’t see it.

Connect the ground wire in the box
Connect the ground wire in the box

Attach the marked wire to the red wire on a two-way sensor switch, or to the “load” terminal if there are no wires, or to the “common” terminal on a three-way switch. For a two-way switch, the last wire in the box goes to the black wire or the terminal marked “line.” For a three-way switch, the last two wires go to any of the remaining terminals or wires. Each terminal holds one wire.

Attach the marked wire
Attach the marked wire

Fold the wires and stuff them back into the box, then push the switch back into place. Install the two screws that hold it to the box, and then use the last two screws to hold the cover plate in place.

Fold the wires and stuff them back into the box
Fold the wires and stuff them back into the box


What do I need to install a motion sensor light switch 3-way?

All you need is a screwdriver, screws, wire nuts, and the motion sensor light switch.

What are the steps for installing a motion sensor light switch 3-way?

The steps are simple: first, turn off the power to the circuit. Next, remove the old switch and install the new one. Be sure to connect the wires properly before turning the power back on. Finally, test the new switch to make sure it’s working properly.

Why would I want to install a motion sensor light switch 3-way?

There are many benefits to installing a motion sensor light switch 3-way. For one, it can deter burglars and intruders. Additionally, it can save you money on your energy bill by only turning on when needed.

How can I make sure my motion sensor light switch 3-way is installed properly?

The best way to ensure proper installation is to follow the instructions that come with your motion sensor light switch. Additionally, it’s always a good idea to consult with an electrician if you have any questions or concerns.

Are there any tips for installing a motion sensor light switch 3-way?

Yes, there are a few tips to keep in mind when installing a motion sensor light switch 3-way. First, be sure to turn off the power to the circuit before beginning. Second, make sure all wires are properly connected before turning the power back on. Finally, test the new switch to ensure it’s working properly.


You just put in your own motion sensor switch, which is the first step toward automating your home. What comes next? A new light with a motion sensor for the porch outside? A new light fixture or an old outlet that needs to be replaced? All of these are easy for a homeowner to do with just a little bit of training.



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