Summarize this article:

Find the circuit breaker or fuse box, which will be in the basement or bottom floor of your home. Flip the switch for the garage. To test for an electrical current, plug a radio or lamp into a wall outlet in the garage. If the power is off, the device won't turn on. Pick an outlet as close to the door as possible to make installing the floodlights easier. Use a screwdriver to loosen the outlet. Remove the screws on the sides of the outlet to free the wires. Leave the electrical box containing the wires in the wall. Visit a home improvement store to purchase an extension box that is the same shape as the outlet. The mounting plate will be included. Fit the plate around the electrical box and, using the included screws, fasten it to the wall. First, look for a circle, also called a knock-out plug, on the top surface of the extension box. Use the tip of your screwdriver to pry the plug up and away. Then position a 12in (1.3cm) metal conduit connector on top of the hole. The metal conduit connector, along with other conduit pieces, can be found at most home improvement stores. The extension box will come with 2 long screws. Position the extension box on the plate with the conduit connector facing upwards. Line up the holes on the box and plate, then use the screws to fasten them together.
Turn off the electricity to the garage. Unscrew a wall outlet near the garage door. Screw a metal mounting plate over the electrical box. Attach a metal conduit connector to the extension box. Screw the extension box to the mounting plate.