neutral calculation please help

[Matt Mckenzie]

On a single phase service when calculating the neutral load do we add up all the 120 volt loads in volt amps then divide by 2 then divide by 120 volt or do we add up all the 120 volt loads in volt amps then divide by 120 volt?

Please help

 

[Smart $]

Of the two methods mentioned, the first is closer to correct, but not completely correct. If only it were that simple. :angel:

For one, you have to include all 3-wire 240V loads. 220.61(B)(1) permits range, cooktop, electric clothes dryer to be factored 70%. After factoring, sum all the 3-wire 240V loads up and divide by 2 for the 120V portion. For there you have to sum up 120V loads on L1 and L2 separately, but as calculated, then take the larger and add to half the 3-wire 240V loads previously determined. Divide that sum by 120V and you have the calculated maximum unbalanced neutral current...