I inspected this home last week with a 600 Amp, single phase incoming service! This could fry you, and your entire high school class-No Romex here! Down stream there were (5) 200 & 100amp panels. There was also a whole-house generator(YES-WHOLE HOUSE).
If you look at the 600amp panel, it makes the 200 amp panel to the left look tiny.
Notice on the exterior shot the bottom access panel has no pad-lock. Anyone can open this panel door making incoming service line completely exposed. Use extreme caution, and if ever unsure how to handle a situation like this…make a phone call- don’t guess!