How To Upgrade A 15 Amp Circuit To A 20 Amp Circuit In Your Home

12 January 2017
 Categories: , Blog


"We need more power!" No,that's not Captain Kirk bellowing an order to Scotty on the Starship Enterprise. That's your family members attempting to add yet more electrical appliances to your already fully loaded home circuit lines.

Adding a power strip only allows you to plug in more appliances. However, it can overload a 15 amp circuit, causing your circuit breaker to trip every time you try to use too many things at once. You can avoid this problem by converting a 15 amp line to a 20 amp circuit. A 20 amp line will be able to provide more power to the existing location and avoid overloaded lines and breaker shutdowns.

What do you need to upgrade to a 20 amp line?

20 amp circuit breaker

Look at your breaker box to find the manufacturer of the box and buy a breaker made by the same manufacturer to be sure that the new breaker will fit into your old box.

12 gauge wire

It's extremely important to switch to at least a 12 gauge wire for a 20 amp line. The current 15 amp line is probably connected using 14 gauge wire, which is too thin for a 20 amp line.

Failure to switch to a heavier gauge of wire could result in overheating and fire, because a 20 amp breaker will allow more power to flow into the line than lighter wire can handle.

You will need a 3 wire sheath of 12 gauge wire (marked "12-3" at your local store). You will need enough wire to reach the distance from your breaker box to the outlet, plus additional wire to navigate around corners and obstructions inside walls and if there are multiple outlets on the circuit. Add several feet to your measurement before buying wire.

You also will need the following tools:

  • Wire cutter/ stripper tool
  • Screwdriver
  • Flashlight

Disconnecting the wiring from the outlet and 15 amp breaker

You will need to turn off the main breakers to the home to work inside the breaker box. The main breakers will be located either at the top of the box or at a separate location inside or outside the house.

When all power is turned off, remove the cover panel of the breaker box and pry the breaker from its slot in the box. You will then disconnect the black wire from the screw terminal on the breaker and the white and green wires that are connected to the white grounding post in the breaker box.

To disconnect the outlet, remove the face plate that covers the outlet and loosen the two screws that hold the outlet inside the wall. Disconnect the three wires on the side of the outlet.

Running the wiring from breaker box to outlet

Pull back the outer sheath of the 12 gauge wire to expose the ends of the three wires inside. Use the wire stripper to remove 1 inch of insulation from the ends of the three wires.

Twist the ends of the three wires to the ends of the wires that were disconnected from the old breaker. Return to the outlet location and begin to pull the existing wiring through the walls until the joined wire ends appear.

Connecting the 12 gauge wires

You will now untwist the joined wire ends and connect the ends of the 12 gauge wire that was pulled through the walls to the outlet. Connect the black wire to the top brass terminal of the outlet by looping it around the terminal screw and tightening the screw securely. 

You will then connect the white wire to the top silver terminal and the green wire to the single green terminal in the same fashion. Push the outlet into the gang box inside the wall and secure it with the two screws, then restore the face plate.

Back at the breaker box, you will cut the wire sheath at a point that allows at least 6 inches of slack inside the breaker box. Pull back the sheath and strip the ends of the individual wires as before, then connect the black wire to the 20 amp breaker's screw terminal and the white and green wires to the white grounding bar inside the box. 

Snap the breaker into the empty slot, screw on the cover panel to the breaker box, and turn on the main breakers. Turn on your new 20 amp breaker and enjoy warp speed power (well, at least enough for a few more cell phones and tablets).

If you feel you cannot do this yourself, it is better to contact a professional electrician to make electrical repairs