Determining Alternate Power Needs (for electric pumps)

I was recently involved with a project concerning a structure in which the fire sprinkler flow requirements could not be met with the municipal water supply.  The fix for this is the installation of a fire pump.  In this instance the design called for an electric motor-driven fire pump.  The question to me was, "Is an alternate source of power required? If so, how can it be supplied, and what criteria must be met?"

Photo by, Crawfish Head

NFPA 1, Fire Code, section refers to NFPA 20 and NFPA 1:13.4 for pump installation requirements.  NFPA 1: requires the approval of all pump installations. 

NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection does not “intend to require a backup source of power for every installation using an electric motor-driven fire pump”. [NFPA 20:A.9.3.2(2)]  An alternate source of power is required only under one of the following conditions:
  • Normal power source is not reliable (as defined in NFPA 20:A.9.3.2)
  • Building height exceeds pumping capacity of fire department apparatus
  • No back-up pump is installed
Questions for alternate pump determination:
  1. Is the structure within the pumping capacity of the local fire department apparatus?
  2. Is the electric-motor driven pump connected to a “reliable” power source?
  3. Will a back-up pump be installed?
If it is determined that an alternate power supply is required, the power supply shall come from one of the following:
  • shall be provided with a generator (in accordance with section 9.6)
  • be connected to a power source independent of normal power (in accordance with section 9.2).
If a generator is to be used as the alternate power source its fuel capacity must be sufficient enough to provide 8 hours of operation at 100% of rated pump capacity.