Section 695.3/Fire Pump Power Supply
NEC 695.3 requires fire pump power to be supplied by a reliable source, with specific requirements for dedicated feeders, connection ahead of the service disconnect, and backup power.
Fire pump power must be supplied by one of the following: a dedicated service (separate from the building service), a tap ahead of the building service disconnecting means, or a dedicated feeder from a listed emergency or standby generator. Section 695.3(A) requires the fire pump supply to be tapped ahead of the service disconnecting means so that opening the building main disconnect does not de-energize the fire pump. The supply conductors must be physically routed to minimize the possibility of damage from fire within the building: they must be located outside the building or, where inside, must be enclosed in 2-hour fire-rated construction or listed electrical circuit protective systems. The fire pump controller must be listed for fire pump service. Overcurrent protection for the fire pump must allow the pump to run under locked-rotor conditions indefinitely without tripping, per Section 695.6. No other disconnecting means is permitted between the power source and the fire pump controller except as required by the utility for connection ahead of the meter.
Why this section exists
The fire pump is the last line of defense in a sprinkler system when the municipal water supply cannot provide adequate pressure. If the fire pump loses power during a fire, the sprinkler system fails at the moment it is needed most. The "tap ahead of the main" requirement ensures the fire pump remains energized even when the building main disconnect is opened for emergency power shutdown. The fire-rated routing prevents fire from destroying the power supply conductors before the fire pump can operate. The prohibition on overcurrent device tripping at locked-rotor current ensures the pump continues running even under the most demanding conditions (a fire that has opened many sprinkler heads, causing the pump to operate at maximum load).
What plan reviewers look for
Plan reviewers check the one-line diagram for the fire pump power supply connection point (ahead of the main disconnect). They verify the feeder routing is outside the building or in 2-hour fire-rated construction. They check that no disconnecting means exists between the supply and the fire pump controller. They verify the fire pump controller is listed for fire pump service. They check that the overcurrent device is sized to allow locked-rotor operation without tripping. For buildings with emergency power systems, they verify the fire pump has an alternate power source (generator with automatic transfer).