Decide on the location for the PIR sensor detector. Locate the nearest wall fixture. Use a ladder if necessary.
Trip the appropriate circuit breaker at the fuse box to disconnect the electric power to the installation area.
Unscrew the light bulb from the light fixture's bulb socket and place it aside. Remove the screws surrounding the light fixture using a Phillips screwdriver.
Pull the fixture off the wall. Twist off the screw-tab connectors from the twisted pairs of wires pulled out of the hole in the wall. Separate the wires from each other. Put the fixture away.
Wind the already-stripped end of the black wire attached to the base of the PIR around the end of the black wire coming out of the hole. Wind the already-stripped end of the white wire attached to the base of the PIR around the end of the white wire coming out of the hole. Twist a screw-tab connector over each pair of twisted wires.
Push the wiring into the wall. Place the base over the hole, against the wall. Insert a wood screw into each hole in the base. Tighten the screws using a Phillips screwdriver.
Loosen the set screw that allows the PIR sensor module to be rotated -- use your fingers to loosen the screw. Angle the sensor module toward the area you want protected so that it faces a 40-degree angle. Tighten the set screw with your fingers.
Insert a floodlight into the bulb socket on the front of the PIR. If there are two bulb sockets, use two floodlights. Restore the electrical power at the fuse box.
Open the battery compartment lid on the side of the PIR. If a screw must be removed first, use a Phillips jeweler's screwdriver to remove the screw.
Place the tip of a flat-edged jeweler's screwdriver against the jumper tab inside the battery compartment. Push the tab to the side that reads "SS" for detection attempts every five minutes. If a different name is used to set the tab against, the instructions that come with the PIR will provide details.
Insert compatible batteries into the battery compartment. Close the lid and reattach the screw, if there is one. Put the ladder away.