How are dwelling unit loads typically calculated for a service-sizing decision?

• A. By counting circuits only
• B. By estimating based on square footage
• C. Using NEC load calculations that include general lighting, small appliance loads, and fixed appliance loads with applicable demand factors
• D. By using a fixed multiplier for all homes

Answer: (C)

Sizing a dwelling’s service starts with applying NEC load calculations. You add up multiple load categories: general lighting load (typically based on the floor area), small-appliance load (the standard allowance for kitchen, dining, and similar spaces), and fixed-appliance loads (like ranges, dryers, water heaters, and other built-in equipment). After summing these, you apply the applicable demand factors from the NEC to reflect that not all loads peak at the same time. This approach yields a realistic, code-compliant service size that accounts for diversity in usage rather than guessing from circuits, square footage, or a universal multiplier.