branch and main breakers

are different brands. What is some verbage that I can use to explain why using a Challenger brand main would be harmful with Cutler Hammer branch feeders?

The labels on the panels specify which manufacturer’s breakers may be used. Challenger was purchased by Cutler-Hammer, so they might be interchangeable.

Here’s an informative link:

When I do cite it, I say this:

“The LOCATION(electric/panels) is equipped with breakers manufactured by a company other than the panel manufacturer. Panel manufactures warn that the use of other types of breakers “voids the warranty, may void the UL listing, and could result in property loss and personal injury.” An evaluation of the acceptability of the breakers by a licensed electrician is recommended.”

Very much appreciated. The EATON site clarified it very well. Yes the Cutler Hammer can be used for Challenger, Westinghouse, and Bryant type that are interchangeable. The chart they provide will be very handy. Here’s the link to it.

Every panel lists what circuit breakers are allowed in that panel. This information is on the label on the inside of the panel cover door.
Anything other then what is listed is incorrect as per then listing and labeling of the panel.