Hello Doug, I beleived that both UL and CSA engineers are correct in testing your component transformer. The reason is that UL required the recognized insulation system. All other agencies (VDE, TUV, BABT, CSA ...) are not required the "insulation system".
UL engineer relied on the recognized insulation system. Thus, he/she determines and verifies the source that generates heat. Other agencies' engineer only verify the compliant rating of material. If you specified the tapes, wires, bobbin material, vanish, sleeving/tubing . . . are UL rated 130 degree (class B); all safety agencies will verify them during evaluation process. However, UL will create a separate file for insulation system (cost of maintenance, follow-up service, imposing the limit on substitution of parts ...). If no UL recognized insulation system (file) is in placed, they will treat that transformer as class A (105) only. Couple of years ago, during UL seminar in San Diego, one asked the question: "Will UL accept the toilet paper roll to be used as bobbin (coil form) if it passed all whatever test required by insulation system?". The answer was NO because toilet paper roll is not an UL recognized material. That's the way it is. Tac Pham ph...@compuserve.com
