Motion Sensor Light Switch

A Lighting Switch Activated by the Detection of Motion

Z22/Wikimedia CC 2.0

When you think of switches, you usually think about walking in your home and reaching out to flip a toggle switch in order to turn on the light. But there is an easier way and it is called a motion detector switch. It is a specialized switch that detects movement in your home by using infrared or ultrasonic sensors. I know it sounds space-age, but it really works. The very fact that it senses motion is a great selling point but add the fact that it can also sense sound makes this switch a must-have in my book.

When someone enters a room equipped with a motion detector switch that is armed with this technology, it turns on the light connected to it and remains on until there is no motion or sound in the room. If you've ever left your home and forgot to turn off the lights or got up in the middle of the night to go to the bathroom or downstairs, only to stub your toe before you got to the light switch, you'll really appreciate the motion detector light switch!

There are many variations of these switches that are determined by the manufacturer. Some of the motion detector switches have a neutral wire connection to power the LED, while others do not. Be sure to check the wiring schematic that comes with your specific model of the switch to ensure you wire it correctly. Normally, the motion detector switch will have three wires. The black wire connects to the incoming "hot" wire which supplies the power to the switch.

The blue wire is connected to the outgoing wire connected to the light that is called the switch leg. The green wire is always used only for a ground wire.

The motion detector switch is composed of these wires, connected to a large eye that protrudes from the front of the switch, usually located on the top of the switch.

It scans 180° from its position on the wall. It is a solid-state electronic switch that can be damaged by incorrect wiring or handling of the product.

There are two variations of this type switch, the active sensor switch and the passive sensor switch. Active sensors, often referred to as radar-based, send out sound waves into the room like your garage door opener does and waits for the signal to return. You may have had a garage door that always opens when it thunders. That's because a frequency was generated that matched the one that tells your garage door opener to open the door.

Passive sensors, on the other hand, have their own unique way of detecting movement. Called passive infrared sensors (PIR) and sometimes called pyroelectric detectors, they are used frequently in homes and businesses alike. They detect heat from the body of humans and animals alike. The sensor uses a photodetector, which converts light in the wavelengths into electrical current that triggers an alarm in the mini computer housed in the detector. It triggers the switch to turn on. The exception is, the computer ignores slow changes in room temperature due to sunlight.

These type of switches are not limited to the interior of the home.

There are also outdoor versions that detect movement from traffic driving up your driveway. These driveway alarms are used to notify someone in your home that you have company, giving you a heads-up before they reach the door. They are also used in things like deer cams and door entry alarms.

The one I have is placed across the room from the door and detects customers as they come in the front door. It then sends a signal to a remote unit upstairs that sounds an alarm. That way, I don't have to sit and watch the video monitor while I eat lunch. That allows me to be aware of customers, eat lunch and watch TV for a few minutes without worrying about missing someone and causing them to wait impatiently. It's one of the best things I've bought and was relatively inexpensive. Maybe, you need a sensor for your home?