Are Breakers One Size Fits All?

Being a home inspector isn’t easy. I’m scolded on a regular basis by listing agents convinced I’ve reported a non-defect. Our most recent transgression? Writing up mismatched breakers. This is when a brand of breaker is installed in an electrical panel that does not match the brand of the panel.

So is a mismatched breaker a defect?

Absolutely. First though, my obligatory disclaimer that I am not code inspector and I don’t inspect homes for code compliance. Moving on. While there is no specific code that prohibits installing a Cutler Hammer breaker in a Square D panel (for example) there exists one code that rules them all. Ok. It doesn’t really rule them all, but every time I reference it, I think of Sauron and his one ring to rule them all.  The NEC states in 110.3  “Equipment must be installed and used in accordance with any instructions included in the listing or labeling requirements” which is reflected in Virginia Residential Code E3403.3 as “Electrical materials, components, devices, fixtures and equipment shall be listed for the application, shall bear the label of an approved agency and shall be installed, and used, or both in accordance with the manufacturer’s installation requirements.  
Interestingly enough, all panels I have ever encountered with a legible label listed which breakers were allowed in the panel, and all but a select few, only listed their own breakers as applicable. It’s even more complicated than that though. Different types of breakers exist within certain brands that do not fit in all of their panels. If you can’t read the label to the right (above on a mobile device) it reads, “This equipment is designed and tested by Square D to performance levels which exceed Underwriters Laboratories (UL) standards and Canadian Standards Association (CSA) standards. Use of other than Square D circuit breakers may adversely affect user safety, impair reliability, and will void the warranty.

That is as black and white as it gets. Mismatched breakers are a defect.

Mismatched breakers Simplified

Maybe the code references and clear warnings aren’t enough to convince you. Perhaps you’re a visual learner. The photo to the left shows two different brands of breakers. They obviously have design differences which is a clear implication of the problem. Breakers are connected to the buss bar in an electrical panel, and using a brand not specifically designed for the buss bar can cause loose connections. Loose electrical connections can cause arcing, pitting, and irreparable damage to the panel.

For the most part, this should be a simple fix, but if the proper breaker no longer exists, it may be a more expensive repair.