Those with memories longer than that of the average mayfly will doubtless recall that lighting in the bus is powered by D cells. It is entirely possible that lighting might be upgraded at some point in the future though this is not likely. Thus, in the meantime lighting has been provided by D cell powered LED lanterns.
Needing light to work on the breaker boxes, when at Harbor Freight yesterday, in addition to more cable loom, I got a few packs of batteries. The D cells were intended for my LED lanterns which were terribly dim. They're a lot brighter now! Out of the lanterns came the above batteries. It's noticeable that both the Dollar General brand and the Sunbeam (probably Family Dollar) batteries both failed with very little use. Of more concern was the condition of the batteries. The Sunbeam batteries are very badly corroded. The Dollar General batteries are less corroded but are still not in great condition.
With the newer Harbor Freight batteries, the lanterns were bright enough to work. The old connecting cable was stripped down to just the black and white wires and the wires inserted into cable loom. Then having connected it all, the connection between white and ground still existed. Clearly I had been in error suspecting the cable. Tracing the connection back, it seems to go to one of my sockets. That's actually quite worrying as I'd been using the electrics for a while without realizing the skin on the bus had been live. Still, I've come to no harm so far.
Interestingly, unscrewing the fastening screws on the guilty socket relieved the problem. As I created a problem for myself by putting over code wiring, thus making the cables very hard to handle, resolving the issue became very challenging.
One of my biggest regrets with my motorhome is that I put in a 120v plugin system. Given that I'll only be using 120v when static, it makes little sense to have 120v when I'm not static. I'd have been better off maybe putting additional solar capacity and a gas cooktop. Just keep electricity to low voltage phone and tablet charging. Having said that, its there so fixing it was the order of the day.
The mystery continued, however. The right hand socket appeared to be correctly wired as did the connection to the breaker box. Still the meter kept telling me that socket had a problem with a connection between white and ground, deepening the mystery. Given that I have just three sockets installed, this is just plain annoying. Perhaps the solution will be found another day. Today it is just too cold to want to bother further. I have no idea why the problem showed up recently when I completed the wiring a year or so ago and never had a problem. Even more bizarrely, I tested the wiring with my meter and it all checked out as fine when I completed it and I did not rush.