Breaker boxes are also called subpanels. They consist of ground and neutral bus bars and space for several circuit breakers. Wires come into the box from locations throughout the house. The wires are run in conduit attached to the box, or are in nonmetallic cable. The wires are usually black, red, white and green. Colored wires are the hot wires. The white wire is the neutral wire. The green wire is the ground wire; ground wires also can be bare copper wire. Heavier wires also come into the panel, providing voltage to the panel.
Things You'll Need
Turn off the main circuit breaker at the meter panel. Cover the breaker with electrical tape to ensure that no one turns it on while you are working.
Remove the cover from the subpanel. Set the voltmeter to 250 volts AC or higher. Touch one of the leads to one of the heavy, colored input wires. Touch the other lead to the other colored input wire. Verify that there is no voltage at the panel. Do not touch the wires with your hands.
Pull enough wire into the subpanel to allow the wires to follow the outer edges of the box and terminate at one of the bus bars. Cut the outer sheath off the nonmetallic cable, leaving about 1 inch where the cable enters the subpanel. Do this by lightly cutting the outer sheath down the middle of the cable with a utility knife. Pull the sheath off the wires and cut it off. Be careful not to nick the inner wires.
Strip 1/2 inch from the ends of the white wires. Connect them to the nearest ground/neutral bus bar. Carefully route the wires around the perimeter of the box.
Strip 1/2 inch from the ends of the green wires. Connect the green and bare wires to the nearest ground/neutral bus bar. Carefully route the wires around the perimeter of the box.
Install one circuit breaker for each colored wire entering the box. Hook the breakers onto the clips along the outer edge of the subpanel, while holding the breaker at a 45-degree angle. Swing the breakers down toward the center of the panel and snap them in place. The current rating of the breaker will depend on the size of the wire and the requirement of the circuits. Most of the breakers will have a 15-amp rating.
Strip 1/2 inch from the ends of the colored wires. Loosen the gold screws on the breakers. Attach the colored wires under the screws of the appropriate breakers. Tighten the screws.
Replace the cover on the panel. Turn on the main breaker.
Keep wires as close to the perimeter of the box as possible.
Regardless of the label, the neutral and ground bus bars are connected together. You can put neutral and/or ground wires into either one, or you can mix them together.
Working with electricity can result in serious injury or death. If you are not comfortable working with it, have the work done by a licensed electrician.