That's a good PDF. So Eaton makes theses breakers which are classified replacements for use in other manufacturers panels. But, for example, would SQ D allow the use in their panel?
Technically,
NO manufacturer of PANELS lists their panels with anything OTHER than their own breakers*. Why would they? Breakers and panels have to be tested together and testing is very expensive, but there is
zero incentive for them to pay to test their panels with another brand of breaker. Most
panels are sold for NEW construction, not retrofits to existing. So you buy the panel and the breakers for it at the same time. If you are the panel mfr, you will not sell more panels just because it is listed with a competitive breaker.
For the Classified breakers however, there IS a market for retrofits, as evidenced by this thread (and many many others). So for the classified breaker manufacturer, they have to buy ONE of each panel they want their breakers listed in and pay to test it with ALL of their classified breakers of that design. It's a much lower cost testing program and stands to have a decent return on that investment. In the case of the T&B panels and breakers, Eaton now owns the rights to both the panels and breakers, so it was a no-brainer for them.
* In days gone by, there was a concept of "universal" breakers that fit in many different panels (Bryant / Westinghouse, Crouse-Hinds / Murray / ITE / Siemens and Sylvania, then later some Challenger) and some panel mfrs listed these competitive products on the panel labels. Sylvania panels comes to mind because I recently saw one that listed Bryant as acceptable replacements. UL changed the rules on that decades ago and came up with the "classified" breaker listing system. One of the reasons was that people kept taking GE THQP breakers and ASS-U-MEd that they fit because they were close, but it required forcing them in and that would actually crack the case. This led to some fires and lawsuits, forcing UL to make the rules a lot more clear.
