How to Replace a Single Pole Breaker With a Double Pole

Open the main service panel.

Locate the main power breaker. This is usually located in the upper portion of the breaker box. This breaker is usually the largest in size and amperage rating.

Turn off the main breaker. This removes power from the entire building.

Unmount the "pigtail" wire from the breaker box "busbar." This wire is held in place with a mounting screw that must be loosened to remove the wire. The pigtail wire is so named because of its coiled appearance.

Remove the single breaker from the breaker box. This is accomplished by pulling it perpendicularly away from the breaker box. These breakers are only held in by friction.

Locate a vacant breaker slot adjacent to the breaker slot where the single breaker was removed. There may be a small faceplate in the adjacent slot. This is removed by prying it out with a screwdriver.

Insert the new circuit breaker into the two adjacent slots. These breakers are keyed to allow for installation in only one orientation. In most cases, the electrical mounting points must face the outside edge of the main breaker box.

Unscrew the mounting screws on the old breaker. These small screws hold one wire each under their screw heads. Note the relative positions of each wire, by color, and remove them from the single pole breaker.

Insert the bare exposed portions of each wire to its previous mounting position, referenced from the single pole breaker, on the double pole breaker. For example the hot wire is mounted above the neutral wire.

Mount the exposed portion of the double breaker's pigtail wire onto the mounting point made vacant from the removal of the single breaker's pigtail wire.

Engage the double pole breaker into the "On" or "Closed" position.

Re-engage the main breaker switch.

Close the breaker box.