Understanding NEC Article 695: Fire Pumps

NEC Article 695 provides safety and operational standards for the installation of fire pumps and their associated electrical systems. Fire pumps play a critical role in fire protection systems, ensuring the reliable delivery of water for suppression efforts.

Scope of Article 695

This article applies to:

• Electric power sources and circuits supplying fire pumps.
• Switching and control equipment dedicated to fire pump drivers.

Exclusions:

• Internal wiring of fire pump systems.
• Jockey pumps and their control systems.
• Testing and maintenance of fire pump systems.

Referenced Standards:

• NFPA 20: Standard for the Installation of Stationary Pumps for Fire Protection.

Key Requirements for Fire Pump Installations

1. Reliable Power Source (695.3)
   • Power must support locked-rotor current of fire pump motors indefinitely.
   • Sources include separate utility services, on-site power production, or dedicated feeders.
   • Backup sources like standby generators are required if reliability is a concern.
2. Overcurrent Protection (695.4)
   • Overcurrent devices must not interrupt fire pump operation, except during short circuits.
   • Devices must handle locked-rotor currents without opening unnecessarily.
3. Fire-Resistive Protection for Wiring (695.6)
   • Conductors routed through buildings require 2-hour fire-rated protection, such as encasement in concrete or fire-resistive cable systems.
   • Supply conductors must be independent and free from damage risks.
4. Voltage Drop (695.7)
   • Voltage at the fire pump motor terminals should not drop more than 5% during normal operation and 15% during startup.
5. Disconnecting Means (695.4)
   • Disconnects must be accessible, lockable in the closed position, and labeled “Fire Pump Disconnecting Means.”
   • They must ensure uninterrupted operation even during maintenance.

Control and Transfer Systems

1. Fire Pump Controllers (695.10)
   • Controllers must be listed for fire pump service.
   • Must include built-in surge protection to handle overvoltage events.
2. Transfer Switches (695.3, 695.4)
   • Listed switches ensure seamless power transfer between primary and backup sources.
   • Transfer occurs within the fire pump room to maintain operational integrity.

Special Considerations

1. Phase Converters (695.3)
   • Phase converters are prohibited due to potential voltage imbalances.
2. Surge Protection (695.15)
   • Surge protection devices (SPDs) are mandatory to safeguard sensitive control electronics.
3. Ground-Fault Protection (695.6(G))
   • Ground-fault protection is not allowed, as it could disable fire pump circuits unnecessarily.
4. Control Wiring (695.14)
   • Fault-tolerant circuits must be used, ensuring pump operation continues despite external wiring issues.

Applications

NEC Article 695 supports the safe installation of fire pumps in:

• Commercial Buildings: High-rises and shopping centers.
• Industrial Facilities: Factories and processing plants.
• Institutional Buildings: Hospitals and educational facilities.

Conclusion

NEC Article 695 provides detailed requirements for fire pump installations, emphasizing reliability, safety, and compliance with fire protection standards. Adherence to these guidelines ensures operational integrity during critical fire suppression scenarios.