Catching up... And after unplugging the shore power cord, shutting down the power post, confirming with my multimeter that there was no power, I opened the plastic shield that protects the panel switches. Then removed seven screws that hold the hinged distribution panel in place.
Finally I took my notes from previous picture (black is house, red is air-condition, neutral, ground) and wrote on the bulkhead for the next guy that comes along. I took pictures of course.
I did take your advice and disconnect all the inputs from those first three buss bars, leaving the ground unchanged. I did leave the top feeder lines intact that go to the two switches. All three (black, red, white) are now labeled. 1 (undisturbed) plus 2,3,4.
It really is logical once you look at it.
Then to the switch. I brought a set of five different colored electrical tape and an ink pen. Plus my phone. I labeled each wire where it came from and where it goes to. Colors were matched too. It is well coded.
The only "problem" was that I had to remove the front plate from the switch in order to access four screws that hold the two parts of the switch together. That was a pain. Then sliding the switch forward should have been "easy" however the screws were out a bit to allow the wires to be removed. With the screws out came problem three:
The screws I had loosened to remove the wires were out too far to allow the switch to come through the panel. So, screwed them in and voila: the part is out!
From the top all looks well, however...
This is not good... and it gets worse:
We know beyond a shadow of a doubt that this is the source of the problem and it needs to be replaced. There will be zero attempts to clean it up. Basically heat is bad, and this is definitely bad.
Though the Air-Conditioning distribution panel switch is functional, I wanted to see what it looked like too. So, I took pictures. This is the bottom and what the house switch should look like:
I have discussed with the owner where to go from here. He gave me his credit card to order the new switch (thanks for that link up the thread a bit). Previously I had verified that the power is identical at the switch and the air-conditioning distribution panel (no degradation/no difference in voltage) and it is visually fine. At this time the owner opted not to replace that switch.
The vessel bilges are dry so all is well. We have time to get the new switch in and install it. By then the owner should be doing better. Falls are Dangerous!!!
I do thank you for the advice so far... and will reconnect the three wires that come from the 50A 125/250V power cord after the new switch is installed. For now she (the boat) is disconnected from shore power. I am not certain how the owner will chose to deal with the port and starboard 30 amp power feeds.
She is a great boat however at 50-plus years old some of the things that were standard back in the day have been superseded by safer choices nowadays. It is one of the things I remind myself of regularly: just because we did it 60-years ago on our boat doesn't mean it is best practice in this century.
Once again, thank you Sirs.