How to Install a Square D Tandem Breaker

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Things You'll Need

  • Insulated screwdriver

  • Wire strippers

Square D Tandem Breaker

What happens when you need to add a circuit to your home, but there are no available spare breakers in your Square D electrical panel? If your panel supports QOT tandem breakers, you simply replace one of your existing single pole breakers with a tandem breaker. This enables two individual circuits to be powered by a double breaker designed to fit in a single space.


Step 1

Open your electrical panel's cover. Depending on your panel's model, the door may have a hinge that allows you to remove two or three screws to swing open the door. Other models may require you to remove all of the screws to remove the panel cover completely.

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Step 2

Tandem breakers are universally installed at the bottom of the panel, and depending on the size of your service, there are only a few slots available. This is to prevent homeowners from installing too many circuit breakers in their panel. Too many breakers in a panel is a fire risk as the load is often more than the main breaker is capable of handling.

Step 3

Before you remove your existing single pole breaker, make sure you turn it off. Use the insulated screwdriver to loosen the screw that is holding the wire in place on the breaker. Carefully pull the wire out and bend it out of the way.

Step 4

Be extra careful removing the existing breaker because the bus is hot. Pull the breaker toward the outside of the panel with care. The breaker will release from its slot.


Step 5

See the knife-like mounting cam near the bottom of the breaker?

The new tandem breaker has a knife-like mounting cam that fits in the open pan rail slot on the mounting rail bead. Take a look at the breaker and the mounting rail to familiarize yourself with each of them. Next, make sure each of the tandem breakers are off. Loosen the two terminal screws before you install the breaker.


Step 6

Slide the breaker's mounting cam into the open pan rail slot first. Then proceed to slowly slide the breaker into place. You may have to add a little pressure to seat the tandem breaker completely.

Step 7

Insert your existing circuit line under one of the terminals and tighten the screw down to secure it. Next, insert the feed line for your newly run circuit under the second terminal and secure it in place. Give each wire a light tug to ensure that the connections are tight.


Step 8

Turn both breakers back on. Be sure to make the necessary changes to your panel's charter. Replace the panel cover door and you're all finished.


If you are adding a circuit to your home, call your local zoning official to see if you need a permit to do so.


Before attempting any electrical work, practice extreme caution. If you are uncomfortable working around your electric panel, by all means, hire an electrician.


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