How Are Motion Sensors Wired?
Motion sensors are normally wired with 4-wire connections. Most use Normally Closed (NC) wiring that is wired in Series. Two of the wires are for power, and the other two are for data. The power wires go to the ECP bus for the panel. The data wires go to the specific zone terminals.
Motion sensors are used for detecting movement in an area. Most work using passive infrared (PIR) technology. This involves looking for the changes in infrared (IR) energy that occur with movement. If a person or large object comes within the sensor's field of view (FOV), then the sensor will detect the change in IR energy. The sensor will then alert the panel. The system will then respond based on the Response Type for the associated zone.
Motion sensors use a small amount of electrical power for their basic operation. For hardwired motion sensors, this power is drawn from the panel. The motion sensor will need connections for power transmission. It will also need connections for data transmission. Most hardwired motion sensors use two wires for both of these processes. In other words, they use two wires for power and two wires for data. That is four wires total. The power wires will go to the ECP bus that powers the system's keypads. The data wires will be connected at the specific zone terminals.
Most wired motion sensors use Normally Closed wiring. This is also commonly referred to as Series wiring. If you have multiple motions wired to the same zone, they will be wired in Series. There are some hardwired motion sensors that will allow users to choose between NC wiring and Normally Open (NO) wiring. These are commonly referred to as "Form C" motion sensors. Normally Open wiring is also referred to as Parallel wiring. But most motion sensors will use NC Series wiring. Check with your motion sensor to find out which wiring configuration to use. We recommend using 18-gauge stranded cabling for motion sensors. However, slightly thicker or thinner wire (e.g. 16-gauge or 22-gauge) should still work just fine. Just make sure the connections are nice and secure. It is also recommended that you use an end of line resistor (EOLR) with your motion sensors. This way, the system will know if anyone tries to tamper or disconnect these devices.
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