Each apartment in a 30-unit apartment complex has a 2 kW water heater. Using the standard method, what is the demand on the service for these water heaters?

Each apartment in a 30-unit apartment complex has a 2 kW water heater. Using the standard method, what is the demand on the service for these water heaters?

• A. 30 kW
• B. 45 kW
• C. 60 kW
• D. 75 kW

Answer: (B)

The standard method uses a demand factor to reflect that not all water heaters will run at the same time. Start with the total connected load: 30 apartments × 2 kW each = 60 kW. For 30 dwelling units, the standard method applies a factor of 0.75 to account for non-simultaneous operation. 60 kW × 0.75 = 45 kW. So the demand on the service for these water heaters is 45 kW. (If you used the full load, it would be 60 kW, but the standard method reduces it with a demand factor.)

The standard method uses a demand factor to reflect that not all water heaters will run at the same time. Start with the total connected load: 30 apartments × 2 kW each = 60 kW. For 30 dwelling units, the standard method applies a factor of 0.75 to account for non-simultaneous operation. 60 kW × 0.75 = 45 kW. So the demand on the service for these water heaters is 45 kW. (If you used the full load, it would be 60 kW, but the standard method reduces it with a demand factor.)