When sizing standby power, which guideline is recommended?

• A. size the generator by total load
• B. consider only the highest horsepower pump when starting
• C. oversize by 20%
• D. ignore standby loads

Answer: (A)

The main idea is to size standby power based on the total load that the system could draw, including all equipment that may run and the inrush when motors start. This ensures the standby generator has enough capacity to handle the full demand rather than just the largest single motor.

Sizing by total load accounts for running requirements and the startup surges of multiple devices. If you only consider the highest horsepower pump, you might miss other pumps or loads that start at the same time or have significant startup currents, risking under-sizing. Ignoring standby loads or using a fixed oversize rule can either miss real needs or waste capacity.

So, using the total connected load as the guideline ensures the standby power system can reliably meet the full, worst‑case requirement.