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Thread: standby generator ground fault protection

  1. #1
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    standby generator ground fault protection

    I have an optional standby generator servicing a structure. It is 1500 amps, 480/277. NEC 700.27, 701.27 (emergency systems and required standby) allow ground fault indication but Article 702 has no exception to the ground fault protection requirement for an optional standby generator so ground fault protection must be installed, correct?

  2. #2
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    of course..


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  3. #3
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    Ground fault must be installed as required for feeder/service, no matter. 700/701 allows alarm only. 702 requires trip on ground fault.

  4. #4
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    The issue of ground fault protection is addressed in NEC Article 700 for emergency generators and in Article 701 for legally required standby generators but there is nothing about ground fault protection in Article 702 for optional standby generators. My question is related to optional standby generator systems.

    Message 3 of 11 (7,440 Views)

  5. #5
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    Quote Originally Posted by wyboy View Post
    I have an optional standby generator servicing a structure. It is 1500 amps, 480/277. NEC 700.27, 701.27 (emergency systems and required standby) allow ground fault indication but Article 702 has no exception to the ground fault protection requirement for an optional standby generator so ground fault protection must be installed, correct?
    You are correct. Since 700 and 701 can deal with systems that are life safety they are allowed to continue to operate with a ground fault condition. Art 702 systems have to trip on ground fault.

  6. #6
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    Quote Originally Posted by wyboy View Post
    I have an optional standby generator servicing a structure. It is 1500 amps, 480/277. NEC 700.27, 701.27 (emergency systems and required standby) allow ground fault indication but Article 702 has no exception to the ground fault protection requirement for an optional standby generator so ground fault protection must be installed, correct?
    Correct. Additionally, you may want a second CT lead for the generator controller ground fault relay.

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