The secondary power supply capacity required shall include all power supply loads that are not automatically disconnected upon transfer to the secondary power supply.

The secondary power supply capacity required shall include all power supply loads that are not automatically disconnected upon transfer to the secondary power supply.

• A. Only critical devices
• B. True
• C. Only life-safety loads
• D. False

Answer: (B)

When the system transfers to the secondary power supply, only the loads that remain connected after automatic disconnects need to be considered for sizing. The secondary supply must be capable of powering those non-sheddable loads for the required duration, so the capacity is determined by what stays online during transfer, not by all loads in the system. That’s why this statement is true. Loads that are automatically disconnected are not included in the sizing calculation.

When the system transfers to the secondary power supply, only the loads that remain connected after automatic disconnects need to be considered for sizing. The secondary supply must be capable of powering those non-sheddable loads for the required duration, so the capacity is determined by what stays online during transfer, not by all loads in the system. That’s why this statement is true. Loads that are automatically disconnected are not included in the sizing calculation.