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separation of control wiring for Emergency or in this case Hospital EES

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    separation of control wiring for Emergency or in this case Hospital EES

    Designing a very small Type 1 hospital EPSS system. The generator is outside, LS, Crit and Equip Branch ATS's in Emergency electrical room in the building. For the 2#14 start (or possibly 4#14 for start/control wiring monitoring as per caterpillar method), does the LS need to be isolated from Crit and Equipment and Critical be isolated from LS and Equipment? These will be run outside so not in MI for the 2 hour rating required under 700.10.

    Thanks,

    Mike
    Mike Shields, PE
    Boston, MA

    #2
    I have always taken the requirements of NFPA 70 517.31 and NFPA 99 6.4.2.2.1.4 to mean that branch separation begins at the load side of the transfer switches. Also, the requirements of 700.10 do not apply to hospitals. That portion of 700.10 is explicitly removed by NFPA 99-2018 section 6.7.6.2.1.5 as well as NFPA 70 TIA 17-8 (attached).
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      #3
      Yeah - I know that NFPA 99 tried to extricate itself from 700-10 along with three other paragraphs but that "extraction text" didn't make it into Article 517 and therefore IS NOT part of the National Electrical Code and unless your state modifies any of this, and more importantly, not a part of the Electrical Code for the state you're working in. You're right about separation starting on the output of the ATS's but they only made that crystal clear in the last code cycle with changes to 517.26 I believe it was.
      Mike Shields, PE
      Boston, MA

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