“Classified” circuit breakers are made by one manufacturer to be installed as replacement breakers in a panel produced by another manufacturer. They are officially called “UL Classified,” meaning that Underwriters Laboratories has tested and approved them for installation in particular manufacturers' panel boards—often for companies that are no longer in business and replacement breakers would be otherwise not available, but also for currently available breakers.

    Eaton, for example, manufactures UL Classified breakers that are approved for multiple different brands of panels. Download EatonClassifiedBreakers for the full list. 

    Just because one manufacturer's breaker snaps into place in a different manufacturer’s panel does not mean it is safe or acceptable. Sometimes we see five or six different brands of breakers in a single, older panel. You can be sure that most, if not all of them, are not approved to be there. Also see our articles What is the difference between specified and classified circuit breakers? and Can you add circuit breakers by different manufacturers to an electric panel if they fit? and How do I find out the manufacturer of an electrical panel? for more on this issue. 

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Field Guide for Home Inspectors, a quick reference for finding the age of 154 brands of HVAC systems, water heaters, and electrical panels, plus 210 code standards for site-built and manufactured homes, and the life expectancy rating of 195 home components. Available at amazon.com for $19.95.
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Here’s links to a collection of our other blog posts about ELECTRIC PANELS:

• What causes copper wires to turn green or black in an electric panel?  

• What is the maximum number of circuit breakers allowed in an electric panel?

• When should a corroded or damaged electric panel cabinet or disconnect box be replaced? 

• What is a tandem circuit breaker? 

• When did arc fault circuit interrupter (AFCI) breakers first become required?

• Can an electric panel be located in a closet? 

• Can an electric panel be located in a bathroom? 

• My circuit breaker won't reset. What's wrong?  

• What is a split bus electric panel?

• How do I identify a combination AFCI (CAFCI) circuit breaker? 

• Why is a fuse box/panel an insurance problem for homebuyers? 

• Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

• What happens when you press the "TEST" button on a circuit breaker in an electric panel?

• What is a Dual Function Circuit Interrupter (DFCI)? 

• What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?  

• What is the difference between "grounded" and "grounding" electrical conductors? 

• What does it mean when a wire is "overstripped" at a circuit breaker?

• Why is an old fuse panel dangerous?  

• Who is the manufacturer of those "bad" electric panels?

• Why is the circuit breaker stuck in the middle? 

• What is a double tap at a circuit breaker?

• What is the right electric wire size for a circuit breaker in an electric panel?

• What is the life expectancy of a circuit breaker? 

• My circuit breaker won't reset. What's wrong? 

• What is the maximum height you can mount an electric panel above the floor? 

• What is the code required clearance in front of an electric panel?

• What is the main bonding jumper and where do it find it in an electric panel? 

   Visit our ELECTRIC PANELS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.