How to Remove a Knockout from Your Box or Panel

circuit box
What You'll Need
Flat Head Screwdriver

When wiring your home, it may be necessary to access your knockout box to create more breaker locations. Knockouts are a prefabricated hole located in your circuit breaker or panel box. When circuit panels are installed, there are empty breaker spaces left available for future use. To cover these empty breaker spaces, the box has small metal pieces installed over the breaker location, which is called a knockout.

Step 1 - Determine Availability

To determine if you have an available knockout, you need to check the breaker box for a space. A knockout will appear as an empty space in the breaker box covered by a metal piece.

Step 2 - Remove Panel Door

If there is a knockout available for use, the beginning step to remove the knockout is to first remove the door to the breaker box. By removing the door to the panel, you can gain better access to the breaker box and prevent the door from inhibiting your reach. To remove the door, simply unscrew the screws in the door brackets releasing the door from the panel.

Step 3 - Dislodge the Knockout

Dislodge the knockout so you have access to remove it. To do this, wedge the flat head screwdriver into the small slot or slit in the knockout. Tap the end of the flat head screwdriver with the hammer. You are not hammering the screwdriver with force, but tapping the end of the screwdriver to create enough force to make the flat head slightly bend the knockout inward.

Step 4 - Pull Out the Knockout

Once you have bent the knockout with the screwdriver and hammer, you should be able to grip a corner of the knockout with the pliers. If you do not have enough edge on a corner to grasp with the pliers, repeat the previous step to bend the knockout a little more to create a corner large enough to grip. Grab the corner of the knockout tightly with the pliers and twist the knockout. The twisting process should snap or break the attaching tabs of the knockout, releasing it from the electrical box. If the knockout is large or the panel box is large, you may need to use a small file to smooth the burrs left after the tab was broken. You do not want to leave a rough metal burr that could potentially cut or pierce electrical wires.

Step 5 - Replace the Door

After you have completed your work in the panel box, be sure to replace the door to the box. The door is necessary to prevent excess dust and debris from entering the panel box. Simply reset the door to its original location and secure the door brackets with the previously removed screws.


Be sure that when working in the panel box you are careful not to pinch or disturb other breakers or wires. As well, when working in the location of the removed knockout, be certain not to scratch, cut or nick any wires on rough edges of the knockout. Check the edges with your finger before beginning any work to ensure they are smooth. If you need to smooth any edges, simply use the file and lightly smooth the rough spots.