In article , propman wrote:
Doug Miller wrote:


The two legs of a residential electrical service are, in effect, two parallel circuits.

.....with a common neutral wire which must provide a return path for both
circuits.

200A flowing in each of two parallel circuits is 400A total, not 200A.

As long as the neutral wire is rated for an amperage capacity of
400A...if it's not, and you try feeding 400 amps through a wire only
rated for 200A max, what do you think will happen? ;-)

You badly misunderstand how this works. In a 240/120 residential service, the
neutral carries only the unbalanced current (the difference between the
currents in the hot legs, not their sum): if 50A is being drawn on one hot
leg, and 90A on the other, the neutral carries only 40A. If one hot leg is
carrying 200A, and the other 199A, the current in the neutral is *not* 399A --
it's 1A. And if both hot legs are loaded exactly equally, whether that's 1mA
each or 200A each, the current in the neutral is zero.

For 200A service, the neutral does *not* need to be rated for 400A. The most
it can ever carry -- if one hot leg is fully loaded, and the other is unused
-- is 200A, and if the loads are even halfway close to being balanced across
the two legs, most of the time the current in the neutral is far less than
that.