Mike Dolt Enterprises
Mike Dolt Enterprises
User: anbm
Asked on: Friday, March 25, 2011 at 12:08 am EDT
Answered on: Tuesday, May 14, 2024 at 3:14 am EDT
Question: All items described below are 480V/3PH.We have (2) existing generators to feed a paralleling gear.We add a new fire pump ATS that serves the building fire pump, the ATS utility feeder was tapped into building utility xfmr secondary side.We plan to connect ATS emergency feeder to above paralleling gear, however the paralleling gear has no space left to add a new breaker in distribution sections to serve fire pump.Can we tap into paralleling gear bus to feed the fire pump ATS (assuming we will comply with 10' tap rule)? Because this is fire pump, I read through 695 but not sure if I missed anything that prevents this connection.
Yes, you can tap into the paralleling gear bus to feed the fire pump ATS, provided that you comply with the 10' tap rule.
NFPA 70: National Electrical Code (NEC) Section 430.24 Exception No. 2 allows for a tap from a feeder to a fire pump controller if the tap is not over 10 feet long and the overcurrent protection device of the tap conductor is not over 125% of the ampacity of the feeder conductor.
NFPA 110: Standard for Emergency and Standby Power Systems Section 5.3.
4.1 requires that the fire pump controller be connected to the emergency power source through one of the following methods: A separate feeder from the emergency generator A separate section of the paralleling gear with its own overcurrent protection A tap from the emergency power source busIn this case, the paralleling gear has no space left for a separate section. Therefore, a tap from the paralleling gear bus is an acceptable option, provided that it meets the requirements of NEC Section 430.24 Exception No. 2.
Additional Considerations: Ensure that the tap conductor is sized appropriately for the load of the fire pump. Install an overcurrent protection device at the tap to protect the tap conductor. Document the tap connection in the electrical system documentation. Flag for review