How to Connect a Motion Sensor to a Light Fixture

Move the appropriate circuit-breaker on the distribution board to the "Off" position to turn off the power supply to the light. Make sure that it will not be switched back on; stick a warning note on the panel. Return to the light and flick the switch to confirm that the correct circuit has been disconnected.

Remove the bulb from the light and place it somewhere safe where it cannot compromise your safety. For example, place it on a shelf rather than in a trouser pocket adjacent to a major artery.

Unscrew the light fitting from the wall and carefully lift it away to expose the wiring.
Locate the red or black power wire and the white neutral wire. Connect a digital multimeter between the power and neutral wires to confirm that the circuit is dead, then make a note of which colored wires are connected to each terminal.

Select an appropriate position at which to attach the motion sensor, close to the light and where the infrared beam can point toward the area in which motion will be detected. Follow the manufacturer’s instructions to attach the sensor to the wall. This usually involves marking the sensor position on the wall, using an electric drill fitted with a masonry bit to drill mounting holes in the specified positions and then screwing the sensor to the wall. Make sure that the sensor cable is on the side nearest to the light fitting.

Feed the cable from the sensor into the light fitting using a route appropriate to the situation. Most recessed wiring boxes have knock-out plates on the sides to allow additional cables to enter the box, and surface-mounted light fittings usually have a hole in the casing through which an additional cable can be passed.

Strip the last 2 inches of outer insulation from the cable, using wire strippers or a sharp knife. When the inner wires are exposed, strip the insulation from the final 1/4 inch of each wire and twist the fine filaments together to create a stiff end on each wire.

Twist together the white wire from the wall and the white wire from the motion sensor. Connect the joined wires to the terminal on the light to which the white wire from the wall was previously connected.

Connect the black wire from the wall to the black wire from the sensor. Join them together with a crimp-on wire connector or twist them together tightly and wrap them with black insulating tape.

Connect the red wire from the sensor to the black wire from the light fitting. Join them with a crimp-on wire connector or twist them together tightly and wrap them with insulating tape.

Connect together all the bare or green wires and attach them to the grounding terminal if one exists. Fit the light fitting back on the wall and replace the bulb.