Locate a spot in your home for the sub panel. 2. Remove the cover from the main panel and identify the breaker that is feeding power to the spot you want to use for the sub panel. 3. Disconnect the wires from the breaker in the main panel and remove the breaker. 4. Install a new breaker in the main panel that is the same size as the one you removed. 5. Connect the wires from the old breaker to the new one and put the cover back on the main panel. 6. Install the sub panel in the spot you chose and connect the wires from it to the breakers in the main panel.