Your explanation makes sense and this has been quite the educational exchange of messages. I've looked inside a breaker box plenty of times, and, when my friend (an electrician) added a 240V breaker, told me how both "legs" should be balanced. I don't exactly remember, nor am I asking, but I seem to remember each leg wasn't separated left and right, but odd and even. Maybe I'm wrong, but it's irrelevant to this conversation; I'm just adding this to show I've taken time to listen when people tell things to me.
It's just that most older homes in my area have 100A service (with a 100A main breaker). Until now, I thought (assuming a perfect layout) 50A for one leg and 50A for another leg.
Prior to this conversation, I thought if I had perfect 10A loads to plug into my outlets, assuming I plug five in rooms that are wired on one leg, and the other five in rooms wired on the other leg, then I would be at the maximum my service can provide (50A on one leg and 50A on the other leg totaling the 100A).
If I understand correctly, I'd only be at 50% capacity because I can put another 50A on both legs before tripping the 100A main breaker.
So the main breaker, even though it's marked 100A, is actually 100A for each leg? Obviously it's not a "200A" breaker, but it's handling 100A on both legs?
I get why it's called a 100A service, but say I built a house that required I run strictly 120V, single phase, devices, then why would it not make more sense to say I have a 200A service panel?
My house has been upgraded to 200A, this means it's technically 400A (200A per leg)?