When sizing standby power, which criterion is used to determine generator size?

• A. Overall number of circuits
• B. Ambient conditions
• C. Total load
• D. Color of building

Answer: (C)

Sizing standby power is about meeting the total electrical load that must be served during an outage. To determine generator size, you sum the wattage (or VA) of every device, circuit, and piece of equipment that will be powered by the generator and choose a unit rated at or above that total. In practice, you may apply diversity or demand factors to reflect that not all equipment runs at full load simultaneously, and you must account for starting currents for motors so the generator can handle brief surge without voltage drop. Ambient conditions can cause derating and reduce available output, but they don’t define the required size by themselves. The number of circuits or other non-load aspects isn’t the driver for sizing, and color of the building is irrelevant.