The electronics are designed to fit in a standard 5/8" PVC conduit. The sensor completely submerges in a 5/8" PVC Conduit. So it is easy to mount the sensor in a ceiling or wall because only a small hole is required, ca 13mm.

The mini motion sensor is "3-wire" connected to a 24V input. Three wires are required to power the sensor and also get movement. One wire connects 24V to the sensor, one wire to 0V, the third wire is the signal wire and is connected to the input of the controller as shown in the diagram.