A circuit breaker is a safety device required in every household electrical circuit by the National Electric Code. It protects you from fire and electrocution by stopping the current when there is a surge from a short circuit or some other malfunction. The solenoid inside the breaker develops enough magnetic force to open a switch when the current exceeds a preset value. When you have corrected the problem, you can then reset the breaker by closing the switch.
Step 1 – Open the door of your service panel and turn off the main breaker. Remove the panel cover by removing the screw that holds it and lifting the plate while you pull on the bottom. When the plate is off, keep your tools and hands away from the brass bus bars. They are still charged, even though the main breaker is off.
Step 2 – Feed an electric cable into the panel. You can feed it through a hole occupied by other cables if there is room. Loosen the clamp holding the cables with a screwdriver. Feed the new one through, giving yourself enough slack to make connections. Tighten the clamp. If you need a new hole, punch it out in the side of the panel with a hammer and screwdriver, then attach a cable clamp.
Step 3 – Strip enough sheathing from the cable so that all the wires can reach their destinations, keeping in mind you may have to route them around the top or bottom of the panel. Make a crosscut in the sheathing with a utility knife, being careful not to cut into the insulation of the wires underneath. Pull the sheathing off with pliers.
Step 4 – Expose 1/2 inch on the ends of insulated wires (black, white and possibly red) with a wire stripper.
Step 5 – Connect the white wire to an available lug on the silver bus bar. Loosen the lug with a screwdriver. Feed in the end of the cable and tighten the lug. Connect the bare wire to the ground bus in the same way.
Step 6 – Connect the black wire to a circuit breaker. Loosen the screw in the bottom of the breaker. Feed in the wire and tighten the screw. If you are wiring a 220-volt circuit, there will be a red wire. Connect this to a second breaker in the same way. This breaker should be coupled with the first one in a two-gang configuration, and their switches should be joined.
Step 7 – Snap the breaker onto the brass bus bar. Turn the breaker off. Hold it over an available slot, parallel to the ones that are already installed. Hook or snap the end to which the wires are connected to the panel. Push the other end until it snaps in place.
Step 8 – Turn on the main breaker, and then turn on the breaker you just installed. If it trips, check the circuit for a short, loose connection or circuit overload.