The most frequent cause of transfer relay failure is simple arcing damage of the high current relay contacts, 3 sets of 50 amp double pole contacts (6 contact surfaces). This can usually be repaired by filing the contact surfaces with a thin flat swiss file, and finishing the job with a high quality electrical contact cleaner/restorer chemical like Caig DeOxIt. Transfer switch contact arcing damage can be minimized by using the breaker panel mains breakers to shut off the electrical current at the breakers (and causing the contact arcing to be at the easily accessible and easily replaceable mains circuit breakers), versus the inaccessible and not usually locally available transfer switch relay. The same goes for first connection of power at a new campsite - have your mains breakers off, turn on the campsite pedestal breaker, then turn on the mains breakers last to cause that contact arc to be on the mains breakers instead of in the transfer switch.
If the relay is mechanically switching you should hear an audible "thump" within 30 seconds of applying shorepower from the campsite pedestal to the trailer. It can mechanically switch but not make electrical contact due to the relay contacts being pitted as described above.
BTW, do all wiring and transfer relay repairs WITH ALL SOURCES OF ELECTRICAL POWER TO THE TRAILER OFF.
DeoxIT® dissolves the contamination and protects the surface. This isNOT the Perfect Straw can, it has been discontinued for this product. KEY FEATURES Temperature Range, -34 C (-29 F) to +200 C (400 F).
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