How to Add a Residential Breaker Box
- 1). Flip the house's main breaker to ensure you won't be hitting a hot wire and risking electrocution. On the side of your original breaker box, locate the indented or perforated circles that cover expansion access.
- 2). Knock out a circle on the side of your original breaker box closest to where you plan to install your subpanel, preferably from the inside out to keep the plug from falling into the box. Use a hammer and screwdriver.
- 3). Mark the studs in the wall where you plan to mount the subpanel for reference, using a pencil. Affix the subpanel to the studs with a drill and wood screws. Your subpanel should be mounted as close to the original breaker box as feasible to consolidate wiring.
- 4). Find the bus bar with a brass screw or a strap affixed to it; this is your ground bus. Because your subpanel branches from a breaker with a ground, a second ground is redundant and potentially problematic. Remove the screw or strap to remove grounding from the subpanel.
- 5). Test the bus bars on the original breaker box with the continuity tester to ensure they are dead. If they are, string range cable through the expansion knock-out, inserting a cable clamp in the hole to secure the wire. Strip about 1/2 inch of insulation off each portion of the range cable, and using a screwdriver, fasten one to each connection pole on the 50-watt two-pole circuit breaker.
- 6). Snap the circuit breaker into place on a vacant slot in the original breaker box. Make sure it makes a connection with bus bars behind it so it draws current.
- 7). Run the end of the range cable remaining outside the original breaker box through an expansion knock-out in the subpanel, using cable clamps to secure it. Strip 1/2 inch of insulation, and, using a screwdriver, connect the range cable to the main breaker on the subpanel. The subpanel is now wired and ready to accept new circuit breakers.