#### brother

##### Senior Member

I=sqrt[(L1^2 + L2^2)-(L1 X L2)]

just out of hypothetical conversation with a fellow electrician, what if it was grossly unbalanced and you had 200 amps on L1 and No AMPS on L2. This is basically a 120/240 service to a house.

I said I suppose the neutral would burn up since we use 4/0 4/0 2/0 aluminum for our services. . since using table 310.15(B)(6) allows this for dwellings, 2/0 is only good for 150 amps. but the actual calculation lets you derate the neutral. Of course this would be a long shot since something would have to be GROSSLY wrong for an unbalance current to that degree.

So what do you guys think?