Square D insists that this is a code violation which will result in their warranty void. They went as far as to say that you may lose your license. However, Eaton and the Underwriters Laboratory (UL) would disagree.
Public safety is a factor, which is why a third party, like the UL, lists suitable manufacturer replacement breakers (UL Classified). These breakers meet UL and NEC code regulations. UL has stated that people must adhere to all manufacturer supplied instructions. Moreover, UL also stated that Classified breakers can be used for their approved panels. (Source: UL Marking and Application Guide Panelboards). On the note of warranty void, manufacturers cannot void their warranty if the replacement part has proven to be safe by a third-party, for instance UL (Magnusson-Moss Warranty Act).
Specified, UL Classified / Interchangeable Circuit Breakers
Specified breakers mean the manufacturer has tested the breakers in the panel and listed them to be used in that panel. You have probably noticed “UL Classified” and interchangeable circuit breakers around the market. These are breakers that have been tested in panels that they are approved for, similar to manufacturer specified breakers. Essentially, they are a different brand from the panel manufacturer but are still in their electrical service panel.
There’s a little controversy about UL Classified and interchangeable breakers. Some manufacturers have no problem with Classified breakers while others do. Manufacturers like Square D warns against the use of Classified and interchangeable breakers. They site the National Electrical Code (NEC) Section 110-3(b), which states that using breakers not listed or labeled is a code violation. Their argument is for public safety drawing evidence from past accidents due to the use of Classified breakers in their panel. The images below are damages to a Square D load center from using a classified breaker.
Compatibility Chart
There are charts that show what circuit breakers are interchangeable. For instance, the chart below shows an example of a cross reference of Type CL 1″ breakers that could be interchangeable for panel installations. You can check under the panel column for compatible Eaton UL Classified breakers.
