A real pleasure chatting with you FlasherZ,
I should add that my background is high power electro-mechanical mechanisms for Space Systems, and I design for fault tolerance as repairs are not an option. I've seen a lot things fry, and it's the rigorous environmental testing that ferrets out the workmanship, or the unexpected...
Your last paragraph hit the nail on the head. My home was built in 1958 with a 120Amp Zinsco Panel. In 1970 a tree had wore away the insulation on the drop-line, and crimps w/ electrical tape were used for the repair. In 2006 I did an extensive re-model with a new Square-D 200Amp main service panel on the other side of the house. When PG&E was called to move the drop-line I asked that the damaged line be replaced. "Naw" said the linesman, "this'll be ok". Strike One.
March 2009 I ordered my Tesla MS.
Aug 2009 I added a 7kW Solar System.
Sept 2012 I installed the #4 NEMA 14-50R.
Dec 2012 I got my Tesla MS.
Feb 2013 I received the HPWC and replaced the #4 Romex with #2 Romex.
In March of 2013 while charging after 10pm at 80Amps, the old electrical tape on the drop-line crimps failed and shorted to the Neutral vaporizing it lightning bolt style it in less than a second. Phase balance was lost (94V/146V) and the HPWC shut down. House continued to run due to a solid ground system, but the uneven loads threw off the phase balance. I called PG&E in the morning to replace the damaged drop-line. Linesman said "Naw, this is a #2 drop-line. We don't replace these, we repair them." He cut out the old crimps and damaged wire, synched the cable together and added 3 crimps. Since the line was now too tight, he cut the utility pole end and added 2 more feet with 6 more crimps. Turns out the linesman miss-diagnosed the old wire as it was later discovered to be #4. Strike Two (3,4,5, & 6 as far as I'm concerned).
This June 2014 on what was my birthday the Tesla was set to start charging at 80Amps at midnight. At 12:20am we awoke to pounds on the door, fireworks in the back yard, and 5 fire trucks. This time the short at the crimps involved the insulation as the arc-plasma source, and zipped along the power line for 20 feet lighting up the sky for a good 15 seconds before finally parting and falling down in flames. A dozen firemen in my backyard, I was the only one at my party without a hat. They used my garden hose to put out the still burning insulation. The HPWC had isolated and protected itself, and the Tesla.
PG&E showed up at 2:30am, and I begged the linesman, for my birthday, to please give me a new drop-line. Unbelievably, he said "We repair #2's, we only replace #4's." As he went up in his bucket lift, he discovered it was actually a #4 line that had failed, so he removed all of it, and all the crimps, and installed a #2 with heavy clamps to the main distribution line, and to my #00 service entrance. Finally I am a happy camper.
Other folks reading this - The NEC codes, heat rating, and de-rating for wires and cables used in the walls, attic, and conduits of a home or business are much more conservative than what Power Utility Co's use for wire and cable hanging in mid-air where heat can dissipate. A #2 Romex in your house and a #2 Cable from the utility pole are of different design and use a totally different set rules.
So knock on wood, hopefully I will not need to tolerate any more faults