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Power Restoration Duration for Life Safety Loads

Question asked by Ghada Hajjar on Mar 23, 2018
Latest reply on Mar 23, 2018 by Milton Werner

Dears,

 

Our question is related to the required power restoration duration for lifesafety and firefighting loads.

 

Our understanding is that life safety and firefighting loads shall be energized within 10 seconds of power failure (as per NFPA 70) for all buildings except high rise buildings (as per NFPA 101 - 11.8.5.2.4) where restoration duration can extend up to 60 seconds. Please confirm our understanding or advise otherwise based on the below findings:

 

  1. As per NFPA 70, loads fed from emergency power supply are divided into three branches:
    1. Emergency systems.
    2. Legally required standby systems.
    3. Optional standby systems.
  2. Emergency systems are defined as “Those systems legally required and classed as emergency by municipal, state, federal, or other codes, or by any governmental agency having jurisdiction. These systems are intended to automatically supply illumination, power, or both, to designated areas and equipment in the event of failure of the normal supply or in the event of accident to elements of a system intended to supply, distribute, and control power and illumination essential for safety to human life.” Emergency systems shall be energized in 10 seconds as per NFPA 70 requirements.
    1. Emergency systems cover loads which when stopped during any power supply interruption would produce serious life safety or health hazards such as the following loads:
      1. Illumination.
      2. Ventilation where essential to maintain life.
      3. Fire detection and alarm systems.
      4. Elevators.
      5. Fire pumps.
      6. Public safety communications systems.
  3. Legally required standby systems are defined as “Those systems required and so classed as legally required standby by municipal, state, federal, or other codes or by any governmental agency having jurisdiction. These systems are intended to automatically supply power to selected loads (other than those classed as emergency systems) in the event of failure of the normal source.” Legally required standby systems shall be energized in 60 seconds as per NFPA 70 requirements.
    1. Legally required standby systems cover loads which when stopped during any power supply interruption could create hazards or hamper rescue of fire-fighting operation such as the following loads:
      1. Heating and refrigeration systems.
      2. Communications systems.
      3. Ventilation and smoke removal systems.
      4. Sewage disposal.
      5. Lighting systems
  4. As per NFPA 20, fire pump shall be energized within 10 seconds of power interruption.
  5. As per NFPA 101, the following requirements are applicable:
    1. Lighting shall be energized within 10 seconds (in line with NFPA 70).
    2. Smoke Control or exhaust shall be energized within 60 seconds (in line with NFPA 70).
    3. The following loads shall be energized within 60 seconds (deviates from NFPA 70 and NFPA 20 requirements and applicable only to high rise buildings):
      1. Electric fire pump
      2. Jockey pump.
      3. Air compressor serving dry-pipe and pre-action systems.
      4. Emergency command center equipment and lighting.
      5. Not less than one elevator serving all floors.
      6. Mechanical equipment for smokeproof enclosures.
      7. Smoke control mechanical equipment.
      8. Stairway video monitoring equipment.

Thank You.

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