What Is a Tandem Circuit Breaker? Learn If This Electrical Solution Is Right for Your Home

Looking for a way to split your circuit breaker into two without a lot of hassle or cost? The tandem circuit breaker is here to the rescue. Electrical repairs and installations can be time-consuming and pricey, but a tandem breaker is one solution for homeowners who need a second circuit and don’t want to replace their entire panelboard. Read on to learn what a tandem circuit breaker is and see if one is a good option for your home.

What Is a Tandem Circuit Breaker?

A tandem circuit breaker—sometimes known as a duplex or twin circuit breaker—allows for two individual circuit breakers to fit into a single breaker slot on the same panel. In other words, you can sneak in a second circuit in a panel that’s already full rather than installing a new, larger panel. This can be especially helpful in older homes, where limited space, tight budgets, and strict historical restoration codes can make renovations a headache. 

How Does a Tandem Circuit Breaker Work?

Tandem breakers function similarly to standard circuit breakers, however they control two separate circuits from a single breaker slot. The tandem breaker is divided into two, with each half of the breaker having its own switch and trip mechanism—if one side trips, the other side will continue running.

Advantages of a Tandem Circuit Breaker

There are several benefits to installing a tandem circuit breaker in your home.

Space-Saving

Tandem breakers allow you to double the number of circuits without taking up additional space. 

Cost-Effective

Installing a new panelboard can be costly and time-consuming. Installing a tandem breaker is simpler than making any significant changes, and can be done without the permits needed to upgrade an electrical panel.

Panelboard Size Compatibility

If your current panelboard cannot accommodate a full-sized breaker due to space constraints, the tandem breaker offers a functional solution, fitting into the same space as a full-sized breaker without requiring a larger panel.

Disadvantages of a Tandem Circuit Breaker

A tandem breaker might be a good option for your home, but before installing one, consider these drawbacks.

Potential Electrical Mismatch

While a tandem breaker should fit into most panelboards, not all electrical panels are designed to accommodate the electrical components of tandem breakers. Consult with a local electrician to confirm compatibility.

Reduced Capacity

Tandem breakers do not increase the overall capacity of your panel. If your electrical panel is already operating near its maximum capacity, a tandem breaker might cause it to overload.

Potential Confusion

Because tandem breakers control two circuits from one slot, you might find it confusing to identify which breaker controls which circuit. It’s essential that you properly label and document the breakers and circuits to prevent chaos and ensure safe operation.

Is Your Panelboard Compatible?

Before installing a tandem circuit breaker, you should determine if your panelboard can accommodate one. Here are two quick ways to determine compatibility:

1. Check the model number: Take a look at the model number of your panelboard. The first four digits usually relay the panel’s capacity and whether tandem breakers are compatible. For example: a model number G4050BL1300 suggests a 40-space panel with the ability to support 50 circuits—this would be compatible with a tandem breaker.

2. Check the panel diagram: If you can’t find the model number, look for the panel diagram. This illustration should show allowable breaker placements; slots that support tandem circuit breakers will have a single line inside.