Wiring a Sensor Light Circuit With a 4-way Switch

“To Sensor or Not to Sensor” that was the question.

Automatic lights are great – when you approach the area, they sense your presence and light it up. Great outside a garage when arriving home late at night.

Often I want to illuminate the area and don’t want things going black if I pause to smell the roses.

I wanted a simple setup. A switch I could use to choose between Sensor Control and Always On status with 'instructions' too simple to forget.

I used a 4-way Switch to accomplish this. The diagrams tell the story that took me a while to work out. I suspect there are other applications for this circuit – love to see how you configured yours!

NOTE: There is one issue with this set-up, you cannot turn the power to the device off! The lights are either powered ON, or the SENSOR is powered ON Adding a simple SPST in series with the hot feed allows shutting off power to the entire circuit - no light at all. My setup is in a shed on a circuit switched from within the house so this is/was not an issue. Replacing a Single Gang Box with a 2-gang Box would allow one to mount a 'power' switch on one side and the 4-way adjacent.

There are combination switches that include a 1-w and a 3-way switch in the Duplex outlet form factor. If there is a 1-way 4-way combination available, I've never seen one - if you do send me a link!

15 Amp Single-Pole Toggle Framed 4-Way AC Switch scrounged from a restore for a dollar.

Switch cover plate to match switch (I got fifty of 'em at least - standard light switch cover)

Appropriate residential electrical device boxes

14/2 Solid Romex SIMpull CU NM-B W/G Wire or equivalent (check your codes!)

A Motion Detector Lamp e.g. Heath Zenith Heavy Duty Motion Sensor Security Light (Amazon $18)

Actually, this was written for those folks who have a working motion detector setup on a switched circuit so there may be no need to shop for more than a four-way switch. Look for a used one 'cause the new ones are relatively expensive.

Notice that, in all the diagrams (circuit diagrams) and the photo there are three basic elements to a Motion Detector Light. The power SOURCE, the Motion Detector SWITCH and the bulb (LOAD) that lights up when the rabbit runs by.

The SOURCE is your household electric. Most often there are three wires from the FUSE or BREAKER box. A bare copper GROUND wire, a wire covered in white plastic called the NEUTRAL and a third coated in black called the HOT.

When dealing with 'outside' lights you will most often find the switch that controls the power to that/those fixture(s) will be located opposite the hinges of the doorway leading out to the area. Turn off the power to that circuit at the FUSE/BREAKER box before changing the motion detector as describe here. Don't work on LIVE circuits - you can get hurt.

Now, the Motion detector is in and of itself a switch. It closes when motion is sensed and opens some preset time after motion is last sensed. There are three wires coming from the Motion Sensor. A NEUTRAL (white), a HOT (black), and a red called the SWITCHED leg/lead/wire (you chose!).

Normally the motion detector module is wired into a fixture as shown in the photo where the arrows show how the SWITCHED leg (A) from the SENSOR is connected to both of the bulb sockets (B) in that fixture. Note that the NEUTRAL lead from the Motion SENSOR is similarly connected to the NEUTRAL legs of each socket.

The black HOT lead from the house power is directly connected to the motion sensor and ONLY to the motion SENSOR while the NEUTRAL leg from the house power is connected to the motion SENSOR and to each of the bulbs controlled by the SENSOR.

The bulbs can only get power from the Motion SENSOR when it senses activity and switches the lights on.

Now, these motion sensor makerss realize folks may not want them powered up 24/7/365 and will most often wire them to a switched circuit so they might be turned off completely by simply cutting power to them using an ordinary light switch.

And, because the circuitry within the motion SENSOR allows for it, they added a feature that prevents the lights from turning on regardless any motion if the sun is bright enough and a cool feature that allows the homeowner to switch the lamps on at will by flicking the switch off, then on again in X seconds.

Now, no one seems certain of the value of X without resorting to the teensy 'instruction manual' describing the setup, installation and features in six different languages all on a 'sheet' of paper smaller than a Hebrew Christmas card.

I figured out a (better/'nother) way.

I drew the circuit out on a scrap of paper and submitted it for some lighting contest or another simply stating that, for anyone interested in the result and confident when it comes to home electrical circuits, the diagram would suffice. They disagreed and demanded more detail, images, descriptions and 'splainin.' That was years ago. Today, I got a 'round tuit and decide to try again.

Now, the 'factory' setup for these devices has the output (RED) lead from the SENSOR tied directly to the bulb Socket(s) and the white NEUTRAL from the source is tied/connected to the SENSOR white NEUTRAL and the white NEUTRAL from each lamp socket.

We will not change the NEUTRAL wiring.

I cut the red lead in two and connected the red SWITCHED lead form the sensor to one of the black screws on the 4-way switch and the red lead from the bulb sockets to the gold/brass colored screw on the opposite side of the switch.

I connected the black HOT lead from the SENSOR to the black screw on the right side of the 4-way switch and to the brass/gold colored screw on the opposite side of the switch.

The annotated images of the switch bottom employ arrows to indicate the connections actually made when toggling the switch between positions.

The beauty of the design is that it literally isolates the electronics from the lamps - temporarily, and that's the idea.

As well, I thought it a unique approach to using a household 4-way switch for a non-standard application. I thought to publish it in hopes of finding another unique use of this switch.

There are lots of folks 'out there' on the YouTube taking pictures as they install one of these lights or replace the motion SENSOR. I'll share one such title here: "How to Replace a Motion Sensor Light" and assure you that you will likely find a dozen others should you need additional detail.