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Chapter references are from NFPA 110, 1999 edition unless otherwise noted.
  • Level 1 EPS systems need to be in a separate room with a 2-hour fire rating or in an appropriate enclosure outside of the building. EPS equipment like battery chargers and transfer switches may be in the same room, but no other equipment is allowed in the room. Chapter 5-2.1

    EPSS equipment except for transfer switches may not be installed in the same room with normal electrical service. Chapter 5-2.2. However, transfer switches may be installed with normal electrical service provided clearances are twice that required in NFPA 70, National Electric Code, 1999 edition, table 100.26 (a). That would be a minimum of 6 feet or 8 feet depending upon the arrangement of the other equipment in the room. This exception is removed with the 2005 edition of NFPA 110.

    NFPA 110, 2005 edition, chapter 7.2.2 disallows EPSS equipment from being installed in the same room as normal service equipment where the normal service equipment voltage is rated at above 150 volts to ground or greater than 1000amps.

  • Storage is not allowed in the EPSS room. Chapter 5-11.1
  • Ready access to the equipment is required with a minimum of 30 inches clearance all around the EPSS. Chapter 5-2.5. The clearance is expanded to 36 inches in the 2005 edition. Chapter 7.2.5, 2005 edition

    In addition, units installed outside must be 5 ft. from combustible walls or openings. NFPA 37, 1998 edition, chapter 3-4.4.1

  • City water cooling systems are not allowed. Chapter 5-8.2 and NFPA 70, 1999 edition, chapter 700-12 (b) (3)
  • Adequate ventilation is required by chapter 5-7.2. The engineer or contractor will need to calculate the size of the air intake and exhaust louvers against the EPSS’s heat rejection through the radiator and into the room from the engine in order to keep the temperature rise in the room below 20o F. He will have to take the airflow created by the engine fan into consideration and keep the static pressure in front of the radiator within the manufacturer’s recommendations. He can do this. It’s not as hard as it sounds.
  • All accessories needed to serve the EPSS, like the electrically powered fuel pump, must be supplied electricity from the load side of ATS. Chapter 5-12.5

Be Careful!

Generators and automatic transfer switches as well as their appurtenant devices employ high voltages that can hurt you. Do not attempt to work with this equipment unless you are qualified. Observe all rules and cautions found in the manufacturer’s manuals as well as NFPA 70E, Standard for Electrical Safety in the Workplace.

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