Mobile Home 'lectric in general...if you touch anything you incur liability exposure.
I regret every moment I have ever spent working on trailers, the entire wiring is installed by minimum wage people, the materials as cheap as the mfg. could get by, the majority of occupants are are of limited resources such that they can't afford to fix it right, where do you stop? The last situation I found a QO panel with a burnt bus, the old guy was trying to fix the place up to make it liveable, he had fixed the roof, the entire floor was dissolving, so was the electrical wiring. He could not afford the $ 300 price for a deeply discounted panel replacement...
As for the black Romex, TEKid,the color of the sheath has nothing to do with the contents of "old" NM; Turquoise, white, black, grey.
