How to Add a Breaker to a Fuse Box


A circuit breaker is a switch that operates a smaller circuit of power through the main fuse box. The fuse box, also called main box or panel, is the place where the main power line is broken down into smaller increments and routed to the rest of the house or building. Individual circuits control the power to a particular area, and there are times new ones need to be added for additional power.

Things You'll Need

  • Flashlight or battery operated work light
  • New electrical cable
  • New circuit breaker
  • Cable clamp
  • Wire cutters
  • Utility knife
  • Shut down the main power switch on the circuit box. This will shut down the power to the entire house, but when working with your main electrical system safety is crucial as one wrong move can cause extreme injury or death. Set up your flashlight or work light so you can see the area you are working in.

  • Install the electrical cable for the new circuit into the box. This wire should already be attached to the fixture or circuit it is powering at the other end. You may need to open a new knock out in the bottom of the box for this, they are the small round punched areas. Place the cable clamp in the opening first, then slide the new electrical wire up through the clamp. Do not tighten the clamp yet. Leave a few inches of wire available in the box to work with.

  • Remove the insulation from the outside of the cable wire carefully with the wire cutters. Do not cut through the individual wires inside the cable, just remove enough insulated coating from the wires to attach them inside the box. Judge what you need to remove as you work based on the location of the breaker inside the box.

  • Attach the bare copper colored ground wire to the ground bus bar on an open screw. Tighten the screw so the wire is firmly attached and won't come loose later. When electricity runs through the wires there are heating and cooling sequences, and this can cause loose wires to pop off a screw not tightened properly.

  • Install the white wire, which is neutral, on the neutral bus bar in the same way you attached the ground wire to the ground bus bar. Be sure a bare end of the wire is attached to the screw and the insulation on the wire is stripped back far enough not to interfere.

  • Strip the end of your hot wire, or black wire, from the new electrical cable, and attach it to the screw on the new circuit breaker. In some cases depending on the amount of power for the breaker or you configuration, you may attach the red wire also, in this case two screws will be present and they will be marked so you know which wire to attach to which screw. Tighten the screw.

  • Push the circuit breaker into the open slot on the circuit bus bar. The circuit breaker should just push in and is held by spring clips. Once the circuit breaker is firmly seated, tuck all your wiring neatly into areas not interfering with anything else, then tighten the cable clamp for the new electrical cable so it is held firmly in place. Remove any tools from the box, and restore the power to the circuit box with the main switch.

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