Modern houses have different electrical needs from houses built just a generation ago. Today's families have more gadgets and toys to be plugged in, and electrical outlets often seem to be at a premium. Changes in those gadgets also change our needs: For instance, instead of massive entertainment centers, many homes now have wall-mounted flat-screen televisions. To conceal the power cords for those televisions, some homeowners are installing an electrical outlet behind the television instead of near the floor.
Turn off the power to the outlet near the floor by removing the fuse or turning off the breaker. If you have a voltage tester, use it to test whether the power is off. If you don't have a voltage tester, plug in a lamp or other small appliance that you know works.
Find a spot on the wall straight up from the existing outlet using the carpenter's level. Use a stud finder to locate the closest stud, and position the new box so that it is slightly farther from the stud than the box below it. Place the new outlet box on the wall and use a pencil to trace its outline. Poke the tip of the wallboard saw through the wallboard on one corner of the outline and cut a hole for the new box. Trim the hole if necessary so the box will fit. Open a knockout on the bottom of the new box.
Remove the cover plate and set aside. Remove the screws at the top and bottom of the plug. Pull the plug out of the outlet box and remove the wires from the plug. Some plugs will have the wires screwed to the side and some will have the wires sticking into the back. If the outlet is the second kind, push a fine-tipped screwdriver into the slot alongside the wire to release it. Open a new knockout on the top of the existing box by prying it out with needle-nose pliers and a screwdriver. Push the end of the cable through the top of the old box and start working it up through the wall. Watch for the end of the cable in the upper hole. If there is insulation in the wall, you may need to use a fishing tape or other device to make feeding the cable easier.
Pull the cable through the hole and pull approximately a foot of cable through the knockout in the new box. Slide the remodel box into the hole and mount it according to the installation instructions. Cut the cable at the lower end, leaving about a foot of cable hanging out. Use a utility knife to cut the sheathing from the cable at both ends so that you can separate the wires.
Remove an inch of insulation from the black and white wires at the bottom of the new stretch of cable using a wire stripper. Place the bare ends of the black wires together, push on a wire nut, and screw it tight. Repeat with the two white wires. Either connect the bare (ground) wires with a wire nut or twist the wires together with pliers. If there is another plug farther along in the circuit, the existing plug will be connected to two wires of each color. In that case, you must remove the short "pigtails" of wire connecting the outlet to the bundled wires and replace the pigtails with the ends of the wires in the new cable. Discard the pigtails.
Strip off about ¾ inch of both the black and white wires if the plug for the new box has screws on the sides. Use the needle-nose pliers to form a loop in the bare end and wrap it around the screw terminals: The black wire goes to the brass terminal and the white wire goes to the silver terminal. If there are holes in the back for the wires, strip off insulation to the length shown by the guide molded into the side of the plug and insert the wires into the holes. The bare wire connects to a green screw on the body of the plug. Carefully tuck the plug into the new outlet box and secure it with the screws at the top and bottom. Use the carpenter's level to get it straight. Install the outlet cover. Install a blank outlet cover over the old hole to cover the wiring.