Service-entrance or feeder conductors whose demand load is determined by the optional calculation are permitted to have the neutral load determined by 220.61.

• A. may
• B. are not
• C. are
• D. must

Answer: (C)

When you use the optional calculation for determining the demand load of a service or feeder, the code allows the neutral load to be determined by 220.61. This is because, in multiwire or 120/240V systems, neutral current isn’t simply the sum of all circuit neutals—it depends on how the loads are distributed across the phases. The optional calculation recognizes this and provides a method (220.61) to size the neutral based on the unbalanced portion of the load, which can often allow a smaller neutral conductor than summing all neutral currents. So for these conductors, it’s permissible to determine the neutral load by 220.61. The other options don’t fit the grammar or the intended allowance.