How are Motion Detectors Wired to a Panel?
Motion detectors are wired to a panel using 4-wire connections. The most common wiring configuration for these devices is a Normally Closed (NC) configuration that is wired in series. Two of the wires transmit data to zone terminals. The other two transmit power from the panel ECP bus.
A motion sensor will detect movement in a specific area. These devices typically use passive infrared (PIR) technology to detect motion. PIR technology involves looking for changes in infrared (IR) energy. Every person and object gives off a small amount of IR energy. When a person or object comes into the field of view (FOV) for the sensor, or moves within the field of view, the sensor will detect the IR energy change. The sensor will alert the panel, and the system will respond based on the programmed Response Type.
To detect movement, the motion sensor will need a small amount of electrical power. It gets this power by drawing from the panel. The motion sensor will need connections for power transmission. The two wires for power transmission are connected from the motion sensor to the ECP bus for the panel. The motion sensor will also need to transmit zone status to the panel. The two wires for this transmission are connected from the motion sensor to the specific zone terminals. In total, four (4) wires are used.
When wiring a motion sensor, you will generally want to use Normally Closed wiring. This may also be referred to as Series wiring. If you have multiple motion sensors connected with the same zone, they will be wired in series. You may also want to use an end of line resistor (EOLR) with your motion detectors. This will let the system know if anyone tries to tamper or disconnect these sensors. However, the use of an EOLR is optional for most panels.
Some wired motion sensors may be able to use Normally Closed or Normally Open (NO) wiring. A motion sensor that can use either NC or NO wiring is what is referred to as a Form C motion sensor. Normally Open wiring may also be identified as Parallel wiring. You should check the installation manual for your motion sensor to determine the wiring configuration. We advise installers to use 18-gauge stranded cabling when wiring motion sensors. That said, slightly thinner wire like 20-gauge or 22-gauge wire should still work okay. The important thing is making sure the connections are secure.
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