Reversed Polarity and Open Ground

SoundGuy wrote:
Why are so many so hasty to declare the OP's surge protector as faulty? As pointed out in that No Shock Zone article I linked to earlier any of these surge protection devices can be fooled if there's sufficient voltage differential between the source neutral and ground ... so who's to say definitively that this isn't happening in the the OP's case? Have they checked? Have they even bothered to check the source with a polarity checker that would instantly indicate any wiring errors? I'll bet not, and I'd also bet that any differential that may exist is varying, which would explain why the surge protector is sometimes fine with it, other times not.

As for the surge protector itself "failing", perhaps it has, meaning perhaps in the past it's been subjected to an excessive surge and has in fact done it's job by sacrificing itself, protecting the trailer's electrical system. The OP seems to be awfully concerned that "the $450 surge protector that has lasted 18 months" has failed where in reality it may have actually done exactly what it was designed to do. To the OP - rather than continue on with these online WAGs call the manufacturer with the details of the unit you have and ask someone who does understand how their device is supposed to work. Good grief! :S

I'm with SoundGuy on this one. I would buy or borrow an outlet tester they are less than $10 and come in handy from time to time.

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Or this one that can also be used to test GFCI's.
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Plug the tester into a 30/15 amp adapter and plug it into the garage outlet. Do the LED's on the tester say the wiring is reversed? If not then remove the protector and plug the trailer directly into the garage wall. Now go plug the tester into an outlet in the trailer and see what it says. If the tester says the outlet is good then the surge protector did it's job and now needs to be replaced. If the tester shows a problem then the surge protector is doing it's job and the problem needs to be fixed in the trailer.

After this the OP should use the adapter and tester to test the campground pedestals every time before he plugs in his trailer.

If the OP lived anywhere near me I would drive over with one of my many outlet testers and test his setup for him.