ya extended mechanical insurance is a pain to get anything done. I didn't use mine at all and got 60% of the cost back as the repairs I had to make were less than the deductable if I did the work myself. the only times I have gotten electric stuff fixed was under the original manufactures warenty for an auto changover switch.
I agree with way2roll, if you know it was a faulty power asource that should be under the liability of the park owner to cover, but it is also your responcibility to know that stuff like this could happen and have a surge protector that shows if the power source is good or not, they are cheep insurance.
