If the Challanger breaker is UL classified for use in the T&B panel, there is no safety problem, just the problem of a voided warrantee. If the breaker is classified, it must have a list of panels it can be used with on the side of the breaker. You would not be able to see this list without removing the breaker. If the Challanger breaker is not classified for use in this panel, then there may be a fire and/or safety hazard.
Don(resqcapt19)
