How to Add a Circuit to an Electrical Panel

When homeowners decide to perform their own renovations or remodeling, there may come a point when they need additional circuits installed to handle the increased power useage of the new room.

This is one of the more difficult electrical jobs for homeowners because they will be working on a "live" electrical panel. But, if you take your time, respect the electricity and use the proper equipment, you will not have a problem. Here is how to add a new circuit to an electrical panel. .

Remove your panel cover. Depending on the manufacturer, there are usually four screws securing it to the panel box. The panel cover may be heavy, so having someone to help you remove it can definitely help you prevent a sliding cover from taking off your toes!

Inspect the interior of your electrical panel. Now, do not get too close--remember--the electrical panel is still HOT! Look to see if there are any circuit breakers that do not have a wire connected to them. If you have an available breaker, then you can use that, but if there are none available, then you will have to purchase a new one. Just be sure to purchase the right brand breaker for your electrical panel. For instance, Square D breakers for Square D panel boxes.

Now comes the time for you to run your new circuit from the electrical panel to wherever the circuit will be located. Do not connect it to the panel just yet. For safety reasons, replace the panel cover until you are ready to work inside the panel.

Start at the end location and work your way back to the panel. If it is easier to run the electrical wire from the panel to the final destination, that is fine, just do your installation from the final location, then back. Meaning, finish installing the receptacles, switches and lights in the end location first, then head back to the electric panel.

Now that you are ready to add the line to the panel, remove the cover once again. Find the main breaker in the electrical panel. It is usually located at the top of the panel, or if you are working in a sub-panel, then it will be located in a nearby electrical panel. Once you locate it, turn it OFF. If the main breaker is in the same panel you are working on, keep in mind that even though it is off, the service cables coming into the panel are still HOT. Depending on your electrical panel, the service cable may enter the panel from the top, side or bottom. Locate them--and then AVOID them.
Note: Having someone hold a flashlight for you while you work will certainly make things go smoother.

If you already have an available circuit breaker, turn it OFF and use your insulated screwdriver to loosen the screw on the clip that secures the wire to the breaker. Next, locate an available knockout on the side of the panel where the circuit breaker is located. Pop out the knockout using the pliers.

Place the cable connector through the knockout (with the clamp screws on the outside of the panel) and secure it to the panel using the included locknut. Loosen the clamp screws on the cable connector.

Pull enough electrical wire through the cable connector so that you will be able to bend it down to the bottom of the panel and then back up again to where the circuit breaker is located. Use a pencil to mark the outer sheath of the electrical wire at the point where it exits the cable connector (on the inside of the panel). Now, pull the electrical wire back out through the cable connector.

Use the electrical wire stripper to slice through the outer sheath of the cable and cut the excess off. Remove all of the paper insulation from between the wires. Inspect the wires for any nicks that the electrical wire stripper may have caused. If there are none, fish the wires back through the cable connector. Proceed with caution and be careful not to nick the wires upon re-entry through the metal cable connector.

With the wire pulled through, tighten the cable clamp on the connector to secure the electrical wire. Be sure that the clamp is tightening down over a SHEATHED portion of the electrical wire, not the exposed wire.

Use the wire strippers to strip away about 3/4 inches of insulation away from end each wire. Locate the neutral bus (it will be the bar that has a lot of white wires already connected to it) and loosen one of the screws that does not already have a wire connected to it. Insert the stripped section of the white wire into the hole and tighten the screw back down.

Locate the grounding bus (it will be the bar that has a lot of bare copper or green insulated wires connected to it) and loosen one of the screws just like you did with the neutral bus. Connect the ground wire to the grounding bus the same way.

Take the black wire and slide it into the circuit breaker's clamp that you loosened earlier and tighten it down. Give the black wire a slight tug to ensure you are tightly secured. Now, bend the wires into the panel so everything is neat and tidy and free from getting caught between the panel and the cover. Double check all of your connections before you close up the panel.

Replace the panel cover. Before you turn the main breaker back on, turn every single breaker in the electrical panel OFF. This is to prevent all of your electrical appliances in your home from immediately turning on simultaneously. Now, with the main breaker turned back on, begin toggling the remainder of your panel's circuit breakers back on one at a time.

With all of the breakers restored, go to where you installed the new circuit and test your outlets or fixtures for power. If you need to find out how to test for voltage, click on the link in Resources below.

Things You Will Need

  • New circuit breaker (if there are no free breakers available in the panel)
  • Insulated screwdrivers
  • NM (non-metallic) cable or electrical wire
  • Romex stripper
  • Wire strippers
  • Pliers
  • Cable clamp with locknut
  • Flashlights


  • Make sure you label the charter on the inside of the electrical panel's door as to what area your new circuit is feeding.
  • If you need to install a brand new circuit breaker, remember to remove the corresponding notch on the panel cover.


  • Avoid the service wires that enter into your electrical panel. They remain HOT even when the main breaker is turned off!