Things You'll Need
Preassembled floodlight kit
Phillips head screwdrivers, #1 and #2
1/4-inch flat-head screwdriver
Combination slipjoint or channel pliers
Cordless impact driver (optional)
Round outdoor junction box
3/8-inch cable clamp (for wood soffits)
Short piece of 1/2-inch PVC conduit (for vinyl soffits)
Male-threaded adapter (for vinyl soffits)
Compact fluorescent floodlights
Pipe thread compound
Sheet metal screws, #8 by 1-inch, stainless steel
Wire stripping tool
A soffit is the covering between the outer edges of a roof and the adjacent wall of the house; it is likely made of wood or vinyl. The main difference between installing a floodlight on this area of your house and installing it on the side of your house is that you will need a junction box in your attic in addition to the one you have on the outside of your house. You will also need an indoor light switch and a power circuit.. Because working with electricity is dangerous, have an experienced and licensed electrician install your attic junction box, light switch and power circuit before beginning this project.
Install the Outdoor Junction Box
Select a site. Select a location that is at least 8 feet from the ground. If your floodlight is a security floodlight, do not point the sensor toward a reflective surface or above any device that may produce heat, such as a heat pump, air conditioner, heater or electric light because they may cause false triggering of the security floodlight. Also check your assembly kit's voltage requirements to be sure you will be able to connect your floodlight to the proper voltage source.
Drill a hole to run new wire. For wood soffits, drill a 1 1/2-inch hole in the soffit; feed about 2 feet of 14-2G wire into the hole. This will be the neutral wire. Once the neutral wire is fed into the hole, have someone hold the wire in place or clamp the wire to the ladder to keep it from falling out of the hole. For vinyl soffits, drill a 1/2-inch hole and feed the neutral wire the same as for wood soffits..
Turn off the power and connect the wire. Once you have turned off the power to the attic junction box, go to the attic and retrieve the end of the neutral wire you fed through the hole. Pull the neutral wire up to the junction box where you are going to connect it, but do not connect it yet. Use an impact gun to staple the neutral wire to the attic rafters, beginning near the junction box (making sure you leave enough length of wire to connect it to the junction box) and working your way back toward the hole in the soffit. Now that the neutral wire is secure and the power is cut to the junction box, connect the neutral wire to the wire in the junction box that the electrician has designated for the flood light.
Prepare your outdoor junction box. For wood soffits, you will only need the center hole on the back of your junction box. Fill in the other holes on the junction box by applying PVC safe thread compound to the plugs provided and screwing them in. Next, attach the 3/8-inch cable clamp to back of the junction box over the center hole. For vinyl soffits, you will only need one of the outside holes on the junction box; fill in the other holes the same as for wood soffits. Instead of the cable clap, you will need a short piece of 1/2-inch PVC conduit pipe with a male-threaded adapter on one end. Apply the thread compound to the threads of the adapter and screw it into the hole you have left open.
Mount your outdoor junction box. For wood soffits, slide the outdoor end of the neutral wire through the cable clamp and the hole in the junction box until the clamp is just underneath the hole in the soffit; tighten the cable clamp screws around the neutral wire. Next, insert the cable clamp into the hole in the soffit until the junction box is flush with the soffit; hold the junction box in place. Using #8 sheet metal screws, secure the junction box to the soffit. There should now be about 8 inches of neutral wire hanging down from the center of the junction box. For vinyl soffits, slide the neutral wire through the PVC conduit, then slide the PVC just through the hole in the soffit; it should be a snug fit. Next, stack enough washers between the mounting ears of the junction box and the siding on the house to make the junction box sit flush against the side of the house (and keep the screws from damaging the siding) and secure the junction box in place.
Strip the neutral wire. Working with electricity is dangerous. Make sure that the power is off, then strip the sheath off your neutral wire and trim about 1/2-inch of insulation off the bottom of the black and white wires. The copper wire is your ground wire; wrap it one time around the ground screw in the bottom of the junction box and tuck the excess into the junction box.
Install the Floodlights
Assemble the lights and gasket. If the gasket is not already connected to the base plate of the floodlights, pull the floodlight wires through the gasket and slide the gasket down until it locks into place.
Connect the wires. Hold the floodlight assembly near the outdoor junction box and connect the white wire hanging from the junction box to the white wires from the floodlights by twisting the bare ends together (clockwise) and securing them with a wire connector; repeat with the black wires. Once the wire connectors are in place, pull them to make sure they are secure.
Secure the floodlights to the outdoor junction box. Tuck all the wires into the junction box. Next, place the base plate of the floodlights against the junction box so that the threaded holes of the base plate match the threaded holes of the junction box. Finally, screw the base plate into the junction box with the screws provided in your kit.
Screw the lamps into place. Once your base plate is mounted to the junction box, you can screw the lamps (bulbs) into their sockets. Follow the kits instructions to adjust the lighting. If you have no instructions, position the lights where you think they should be and test them (after you have restored power); adjust accordingly.
Connect the switch. If an indoor switch has not already been installed, have your electrician install and connect a switch to operate the floodlights from ground level.
Working with electricity is dangerous. Consult an electrician before beginning this project. Make sure the power is off before you touch any wires.