upgrading my 30 amp service to a 50 amp

pianotuna wrote:
Hi,

My understanding is that if both legs are maxed out the neutral will carry nothing.

tahiti16 wrote:
Think you got it right Scott, because if both legs were running at max then neutral would be carrying 100amps so no single leg could ever over load the neutral.

Pianotuna has it correct. Provided the 240V supply is correctly connected (and not both legs connected to a single 110V supply as can happen at some campgrounds) the neutral will only carry the difference between the current drawn on the two separate 110V legs.
To qualify my comment in parentheses, IF both legs of the 50A outlet are connected to the same 110V supply, (ie 0 volts between the two legs) then the neutral will carry the SUM of the two sides. This can result in a dangerously overloaded situation that will not be caught by most breaker setups.