The other side of the coin is, he did not provide us with anything regarding how he knows the electrical source was faulty. That “proofs” could lay the blame on “the electrical source”, while lack of such proof leads to no one to blame. The way I read it, number (b)3 is pretty clear - that coverage is excluded. I’d also note, he never said he was at a campground, he may be his own “faulty source”. Wouldn’t be the first time a do-it-yourselfer wired an RV plug wrong.
This is likely the first issue to overcome. You have to prove an outside force caused the damage. Speculation that there was some sort of power spike with no evidence and they can say it was faulty equipment in the trailer (as opposed to...a huge crash of lightening and immediately, everything blew out.
