210.11 Branch Circuits Required
(B) Load Evenly Proportioned Among Branch Circuits Where the load is calculated on the basis of volt-amperes per square meter or per square foot, the wiring system up to and including the branch-circuit panelboard(s) shall be provided to serve not less than the calculated load. This load shall be evenly proportioned among multioutlet branch circuits within the panelboard(s). Branch-circuit overcurrent devices and circuits shall only be required to be installed to serve the connected load.
So only the circuits that are "calculated on the basis of volt-amperes per square meter or per square foot" need to be balanced? how odd!?
Pierre, I understand your concern completely and I admit I never read 210.11(B) before although I do attempt to balance loads when possible.
But, when converting a 240 panel to 120 you don't need to worry about the "new" neutral wire being smaller because it was originally sized the same as the other ungrounded conductor. At least I would hope it was!
I have never seen a situation where an unbalanced panel caused any hazzard. I guess I always assumed as long as the correct gauges of wire & OC were used, it's not a problem.
I'm very curious, Just how unbalanced were these situations you have seen?