Single utility service point and onsite generator
This project requires design of an onsite generator(s) sized for the fire pump's alternate power source. All the requirements of NFPA 110, ?Standard for Emergency and Standby Power System,? should be met in designing and sizing the generator system. The generator(s) must be sized to start and run the fire pump, along with any additional loads connected to it. As per NEC 695.3(B)(1), it does not need to have the capacity to handle the pump's locked rotor current. Nor does the tap for the generator feeder have to be located ahead of its disconnecting means. The generator does have to have enough fuel capacity to provide eight hours of operation at 100% of the pump's rated load (NFPA 20, 9.6.2.2). The transfer of power (from normal to standby and vice versa) needs to take place within sight of the fire pump (NFPA 20, 9.6.4 and NEC 695.12(A), which means the transfer switch needs to be located in the same room as the pump.
As with the first example, it's best to specify a packaged unit. In this case, a combination automatic transfer switch, disconnect switch, and fire pump controller is the best choice. You'll also need to route two feeders to the fire pump room. Exercise care with the routing, and be sure the cables are properly protected to ensure a successful installation, just as you did in the first example.
