NFPA 20 2003 Edition
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    Code issues affecting standby generator sets.

    NFPA 20   2003 Edition

    (Voltage Dip)

    9.4* Voltage Drop. 

    9.4.1 Unless the requirements of 9.4.2 are met, the voltage at the controller line terminals shall not drop more than 15 percent below normal (controller-rated voltage) under motor-starting conditions.

    9.4.2 The requirements of 9.4.1 shall not apply to emergency-run mechanical starting. (See

    9.4.3 The voltage at the motor terminals shall not drop more than 5 percent below the voltage rating of the motor when the motor is operating at 115 percent of the full-load current rating of the motor.

    (Circuit Breaker Capacity)

    9.6.5 Protective Devices. Where protective devices are installed in the on-site power source circuits at the generator, such devices shall allow instantaneous pickup of the full pump room load.

    9.6 On-Site Standby Generator Systems. 

    9.6.1 Capacity. Where on-site generator systems are used to supply power to fire pump motors to meet the requirements of 9.2.4, they shall be of sufficient capacity to allow normal starting and running of the motor(s) driving the fire pump(s) while supplying all other simultaneously operated load(s). A tap ahead of the on-site generator disconnecting means shall not be required.

    9.6.2* Power Sources. These power sources shall comply with Section 6.4 and shall meet the requirements of Level 1, Type 10, Class X systems of NFPA 110, Standard for Emergency and Standby Power Systems. The fuel supply capacity shall be sufficient to provide 8 hours of fire pump operation at 100 percent of the rated pump capacity in addition to the supply required for other demands.

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