Need to replace Thomas & Betts 2-pole 30 amp breaker for a water heater. What brand would be compatible? Panel is also T&B. TBB10 (20-20) C Model #1
This handy chart seems to show that the Eaton CL230 breaker is a "Classified" replacement for the Thomas Betts TB230 breaker.
Since this is a pretty common breaker sold at national big box home improvement stores it should be straightforward to compare the two. These cheaper breakers are normally not even in a package, making comparison even easier.
The comment from isherwood about the type of panel you have is valid. This is meant to point you in the right direction, but its not a definitive "certified" answer.
Talk to an Eaton authorized dealer, i.e. an actual electrical supply house that deals in Eaton. They can check their cross reference book to see if the BR busing is compatible. There's a possibility, since Bryant has lineage back to Challenger which has lineage back to T&B. But the cross-refernece book will tell for sure.
If not, they can get the Eaton CL that JPhi1618 mentioned.
Either way, Eaton is your one-shop shop.