How to Install a Motion-Activated Security Light

In this video, Ask This Old House Master Electrician Scott Caron installs a light above a garage to illuminate a dark driveway.

Steps:
1. Find an existing source of power near the location of the security lighting and shut off the power to that source.
2. Cut existing wire connections using the wire cutter.
3. Drill an outlet hole through to the exterior siding using a power drill with 1⅜-inch spade bit. Run 14-gauge wire from the inside location to the outdoor location.
4. Assemble the security light fixture.
5. Attach power wires to the light fixture wires and cover with wire connector nuts.
6. Roll out flexible putty and attach around the hole on the exterior of the house. This will serve as a barrier to make it weather-tight.
7. Attach the light fixture and electrical box to the outside siding using a power drill and screws.
8. Replace existing outlet with a switch-over-outlet device that can serve as an override.

Getting a watertight fit against siding with overlapping pieces—such as shingles, clapboards, or vinyl—can be tricky. According to This Old House Magazine, one effective solution is a rigid-foam mounting block notched on the back side to mirror the siding’s overlap profile. Caulk around the top and sides of the block’s back face and press it against the siding, but leave the bottom uncaulked so any water that seeps in can drain out.

When connecting the floodlight wires inside the junction box, tie all four white wires (cable, two lamps, and motion sensor) together. Join the red wire from the motion sensor to the black wires from the lamps. Then join the black wire from the cable to the black wire in the motion sensor. Be sure to wrap the bare grounding wire from the cable around the grounding screw inside the box. Note that wiring on preassembled floodlights may differ from standard configurations—always follow the manufacturer’s wiring instructions or call an electrician.