What is the typical demand factor applied to general lighting in load calculations?

The correct approach to applying demand factors for general lighting in load calculations is based on a standard practice outlined in electrical codes. In this context, the demand factor refers to the percentage of the connected load that is expected to be used at any given time.

The appropriate demand factor method involves taking 100% of the first 10 kVA of the connected load, as this recognizes that the initial portion of lighting load is likely to be fully utilized. Beyond this threshold, it is reasonable to apply a reduced demand factor of 50% to the remainder of the load, reflecting the reality that not all lighting will be on simultaneously at all times.

This approach helps in making more accurate load calculations while ensuring that the feeder and service equipment can handle peak demand without being oversized.

In contrast, using 100% of the first 5 kVA and 25% of the remainder, an 80% reduction of the total load, or 50% of all connected load would not accurately represent the real-world usage patterns of general lighting. Thus, option C stands out as the most consistent with established electrical guidelines.