neuturals

[LAYMAN JOE]

Maybe it would be easier if someone posted the calculation.

What calculation do you use to find the proper size grounded conductor when only one is used in a MWBC?
4 or more circuits.

Also, besides the calculation, what other considerations should one take when sizing a single neutral used in a MWBC? ie., non linear loads that contribute to harmonics.

Thanks.

 

[roger]

What calculation do you use to find the proper size grounded conductor when only one is used in a MWBC?
4 or more circuits.

Joe, use the following formula based on the total load of each phase (not the number of circuits) to find the unbalanced current on the conductor

The load would not change the fact that if there is 40 amps of OCP on any phase of this MWBC the conductor would have to be sized for 40 amps.

SQRT Ia? + Ib? + Ic? - (Ia x Ib) - (Ib x Ic) - (Ic x Ia)

Roger