Are Circuit Breakers Interchangeable?

If it doesn’t fit, don’t make it fit

home inspector explains mismatched breakers

Life’s first lessons

Take a reminiscent moment to reflect back to when you are a small child playing with those shaped block toys. You know… the one where you had to fit a shaped block into it’s corresponding shaped hole. Unless you were the hulk as a child, no matter how hard you tried, the triangle wasn’t going to fit into the square hole. Well, believe it not, this early lesson has a real world electrical application.

Circuit Breakers are not one size fits all

Take a look at the photo below. You can see that the back of these two breakers have two completely different slots. These slots go into a bus bar that is designed specifically, and exclusively for their corresponding breaker. Unfortunately, unlike the blocks, it is possible to force install a breaker on a bus bar that it is not designed for.

this photo demonstrates the difference between two different breakers

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Even if the breakers fit , they may be the wrong type breakers

It is very common for homeowners to want to a add a new circuit, and new breaker to their home, or replace an old breaker that is defective. What most homeowners don’t know is that they need to use the right type of breaker.

At a minimum, you need to make sure you get the right brand. The circuit breaker brand should match the brand of panel. For example a cutler-hammer panel needs cutler hammer breakers, and GE panels need GE breakers.

Even all the breakers made by one manufacturer are not all interchangeable breakers . The panel label on the load center will specify the exact models that are direct fits. A single manufacturer may have several product lines and different types of breakers. You’ll need to make sure you only install the specified breakers.

Here is a photo I took of an electrical service panel label during an electrical inspection. You can see that panel allows different breakers. If you can’t read the small text in the photo it says:

“BRANCH CKT BRKR ARE A-H MURRAY STYLES MP, MM, AND EP;

BRYANT TYPES BRO, BAR, GFCB;

WESTINGHOUSE TYPES QP, QPGF;

ITE TYPES EQP, QF”

this panel label outlines which breakers are specified for this panel

So this particular panel specifies different brand breakers its in compatibility list. Notice it doesn’t just list the brands, it says exactly which parts number of those third party brands are allowed.

Conversely this photo I took of a label shows this General Electric Panel only allows its own breakers.

“Use only GE Type Breakers THQL, THHQL, TQDL, THQDL, or TXQL

Warning: Use only with GE type breakers, use of other circuit breakers voids the warranty, may void the UL listing and could result in property loss or personal injury…”

this label specifies only GE breakers are allowed in the panel

Don’t Make it fit. Now look at the photo below. Notice how there are several brands of breakers and they all look out of place? Well, they are! This panel has a variety of breakers . hese breakers do not belong in this panel and they are loose, and have poor connections. Poor connections with electrical equipment can cause arcs, sparks, and possibly a fire.

Panel manufacturers warn against this on their label as shown above. Generally, if you have for example, a Square D panel, you can only use Square D breakers. However, using the same brand doesn’t always yield the correct results. Most manufacturers will list all of the models of breakers that can be used with the specific panel. Not all of a manufacturer’s breakers, will fit into all of their panels.

if you have a panel like this it is a fire waiting to happen

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The Caveat…There is always a caveat

Up to this point we have been talking about specified breakers. Specified breakers are breakers that the panel manufacturer specifies is acceptable for that panel. There is a such thing as classified breakers. Eaton makes the most UL classified breakers and defines them as:

“UL Classified breakers are produced by one manufacturer for use in place of the breakers specified on the panelboard. Like specified breakers, UL Classified breakers have been tested in the panels for which they are approved.”

Classified circuit breakers are UL listed and meet all the requirements of the National Electrical Code. The Eaton Cutler Hammer Brand makes single pole and double-pole breakers that are approved direct replacement for many different manufacturers and different panels.

This doesn’t mean that all Eaton breakers can be installed in any circuit breaker panel. You can go their website to see if they make a replacement of certain breakers that you need.

Summary

There is no single interchangeable circuit breaker. When working in your electrical panel you always need to use the correct brand of breakers. For the most part, the panel will outline which breakers are specified for that panel. However, use of classified breakers meets the requirements of the National Electrical Code. As always, local code officials get the final say on what is allowed in your area.

Take a moment and go to your electrical panel. Open it and look at the brand on the label. Look for the section that lists what breakers can be installed in the panel.(Do not remove the cover) Some companies own two brands so you may see two brand names. Start at the top breaker and work your way down ensuring that all of the breakers are the appropriate brand. If not, call an electrician.

Always exercise safety when working with electrical devices. Wear the proper PPE, replace breakers with the same amp circuit breaker that was there, do your research, and when in doubt, call a professional electrician.