A transformer supplying a fire pump is not permitted to have secondary overcurrent protection.

A transformer supplying a fire pump is not permitted to have secondary overcurrent protection.

• A. True
• B. False
• C. Not specified
• D. Both

Answer: (A)

A transformer feeding a fire pump is treated as part of an emergency power supply, and the protection scheme is arranged to avoid interrupting the pump during an emergency. Because of that, the secondary side is not allowed to have overcurrent protection. If there were a secondary overcurrent device, a fault or the pump’s starting surge on the secondary could trip that device and cut power to the pump at the exact moment it’s needed most. By requiring protection on the primary side (and within the pump’s control circuit) rather than on the secondary, the system is kept energized and reliable for fire-fighting needs. This is why the statement is true.

A transformer feeding a fire pump is treated as part of an emergency power supply, and the protection scheme is arranged to avoid interrupting the pump during an emergency. Because of that, the secondary side is not allowed to have overcurrent protection. If there were a secondary overcurrent device, a fault or the pump’s starting surge on the secondary could trip that device and cut power to the pump at the exact moment it’s needed most. By requiring protection on the primary side (and within the pump’s control circuit) rather than on the secondary, the system is kept energized and reliable for fire-fighting needs. This is why the statement is true.