When is an automatic transfer switch typically required in NFPA 20 fire pump installations?

When is an automatic transfer switch typically required in NFPA 20 fire pump installations?

• A. Electric-powered pumps that must switch from normal to emergency power
• B. Diesel-powered pumps
• C. Any fire pump installation regardless of power source
• D. When the system is not connected to a standby power source

Answer: (A)

Automatic transfer switches ensure a fire pump keeps power during an outage by automatically switching from normal utility power to a standby (emergency) power source. This is typically required when the fire pump is electric-powered and is intended to run from a standby generator, so the switch happens automatically the moment normal power fails. Diesel-powered pumps don’t rely on switching between two electrical sources; they are engine-driven and controlled separately, so an automatic transfer switch isn’t part of their normal setup. If there’s no standby power source to switch to, an ATS isn’t applicable. So the usual need for an automatic transfer switch is for electric-powered pumps that must switch from normal to emergency power.

Automatic transfer switches ensure a fire pump keeps power during an outage by automatically switching from normal utility power to a standby (emergency) power source. This is typically required when the fire pump is electric-powered and is intended to run from a standby generator, so the switch happens automatically the moment normal power fails. Diesel-powered pumps don’t rely on switching between two electrical sources; they are engine-driven and controlled separately, so an automatic transfer switch isn’t part of their normal setup. If there’s no standby power source to switch to, an ATS isn’t applicable. So the usual need for an automatic transfer switch is for electric-powered pumps that must switch from normal to emergency power.