Loving your build out. It is very inspiring
How did you get all of the materials out there without anyone asking questions?
Wouldn't anything 240v (double pole?) span both poles and create a balanced load? I have a 4 gague 3 wire run from a 100 amp circuit on my main panel to my bunker's panel.
#4 awg wire is not large enough to handle a 100 amp breaker. You need a minimum of #3 or downsize your breaker
the problem at your main is not 240v. It is all the misc 120v loads like microwaves fans hair dryers etc. that can cause a two pole breaker with a breaker tie between the handles to soft trip the overloaded pole and leave the remaining pole on.
Is the meter in the bunker? Is it a smart meter or something? I am trying to figure out how the meter reader is going to come down into your bunker full of plants and read the meter each month.
Quite the collection of skillsets there my man.
I've done some small(in comparison) home improvement projects...finishing correctly seems to be where I stagger, until 'someone' puts foot to ass and gets me moving again
Well done