Under the optional calculation method for a dwelling unit, which statement about the neutral conductor is true?

Under the optional calculation method for a dwelling unit, which statement about the neutral conductor is true?

• A. The neutral is ignored.
• B. The neutral is determined by section 220.61.
• C. The neutral is not used in determining total load.
• D. The neutral is sized at 125% of the service rating.

Answer: (B)

In the optional calculation method for a dwelling unit, the neutral conductor isn’t ignored or sized by a flat rule; it’s specifically determined by a referenced NEC provision. The rule in section 220.61 lays out how to calculate and size the neutral based on the loads used in the optional method, accounting for how the neutral carries the imbalance of currents in 120 V circuits. That’s why the statement that the neutral is determined by section 220.61 is the correct one. The other options misstate how the neutral is treated: it’s not ignored, it is used in the overall load calculation, and sizing it as 125% of the service rating isn’t the method described for the neutral in the optional method.

In the optional calculation method for a dwelling unit, the neutral conductor isn’t ignored or sized by a flat rule; it’s specifically determined by a referenced NEC provision. The rule in section 220.61 lays out how to calculate and size the neutral based on the loads used in the optional method, accounting for how the neutral carries the imbalance of currents in 120 V circuits. That’s why the statement that the neutral is determined by section 220.61 is the correct one. The other options misstate how the neutral is treated: it’s not ignored, it is used in the overall load calculation, and sizing it as 125% of the service rating isn’t the method described for the neutral in the optional method.