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  1. Replies
    1$$
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    This would be a good book to read. IEEE...

    This would be a good book to read. IEEE Recommended Practice for Powering and Grounding Electronic Equipment

    Some of the later chapters have design and installation recommendations
    ...
  2. Thread: NYC power outage

    by ron
    Replies
    42$$
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    2,032

    As you might imagine, no recording and they...

    As you might imagine, no recording and they frowned when I took a picture from my cellphone from the audience. :D
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    If there are no 4W loads, then the neutral can be...

    If there are no 4W loads, then the neutral can be left at the utility disconnect and generator (bond the N-G at both utility disconnect and generator). No need to bring a neutral to the ATS or out...
  4. Thread: NYC power outage

    by ron
    Replies
    42$$
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    2,032

    I attended this lecture...

    I attended this lecture https://events.vtools.ieee.org/m/198911 in May and they were pretty forthcoming with what happened, at least what they knew at the time. Taft was a knowledgeable speaker and...
  5. Thread: NYC power outage

    by ron
    Replies
    42$$
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    2,032

    I was sent an oscillogram from a PQ meter at a...

    I was sent an oscillogram from a PQ meter at a client's data center in Pittsburgh that wanted me to evaluate a 5 cycle momentary undervoltage that they saw at ~7PM on Saturday. I don't have a 138kV...
  6. Thread: NYC power outage

    by ron
    Replies
    42$$
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    2,032

    At this point just that my office was in the dark...

    At this point just that my office was in the dark until about midnight.

    https://www.nytimes.com/2019/07/14/nyregion/nyc-power-outage-con-edison.html
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    12$$
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    For that reason, I do Neher McGrath calcs every...

    For that reason, I do Neher McGrath calcs every time, and we do a lot of UG ductbanks.
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    4$$
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    I think there is a misinterpretation of NFPA 101...

    I think there is a misinterpretation of NFPA 101 7.8.1.2.2 going on.

    You said that the Emergency fixtures are not connected to the occ sensors. Section 7.8 only refers to the emergency fixtures...
  9. Replies
    12$$
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    Without N-M calcs, you are just guessing. I've...

    Without N-M calcs, you are just guessing.
    I've seen pictures of burned up conductors that melted in ductbanks from lack of derate. Granted I work in the data center industry where a feeder is often...
  10. Replies
    12$$
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    830

    Underground low voltage is a real problem in my...

    Underground low voltage is a real problem in my opinion.

    From an enforcement standpoint, the NEC says that Engineering supervision is permitted but not required. Medium voltage underground...
  11. Determine the largest OCPD that could serve the...

    Determine the largest OCPD that could serve the skid (the customer may choose smaller, but who cares) and then choose bonding conductor based on table 250.122.

    Whether it is solidly grounded or...
  12. As you mentioned, everything has to do with the...

    As you mentioned, everything has to do with the load on the secondary. Also the rating of the 2500kVA transformer. If it is straight 2500kVA, then the FLA is 3010A and that is all it can safely put...
  13. 250.112(K) Skid-Mounted Equipment. Permanently...

    250.112(K) Skid-Mounted Equipment. Permanently mounted electrical equipment and skids shall be connected to the equipment grounding conductor sized as required by 250.122.

    250.122 is essentially...
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    4$$
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    Not necessarily. If the loads are 3 wire only,...

    Not necessarily. If the loads are 3 wire only, then no need to bring the neutral out of the generator if you do the N-G bond in the generator.
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    5$$
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    As pointed out, the LV tables are in Annex B, but...

    As pointed out, the LV tables are in Annex B, but Annex B is not enforceable.

    If you were just taking the prescriptive information from the code, what code requirement would make you derate a LV...
  16. Although TIA-607-A is a great reference, there...

    Although TIA-607-A is a great reference, there are plenty of other grounding and bonding references that differ slightly regarding what you describe such as IEEE Std 1100 (Recommended Practice for...
  17. Thread: 4 pole ATS

    by ron
    Replies
    33$$
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    1,295

    We do anything possible to leave the generator...

    We do anything possible to leave the generator with 3W only to an ATS so we don't have to deal with the issue. We bond N-G at the gen and leave the neutral there.


    Imagine you were the...
  18. If the taps are for meter sensing or other low...

    If the taps are for meter sensing or other low ampacity needs, we've used insulation piercing taps when there is room above the lugs.
    ...
  19. Replies
    51$$
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    Gar not cool i posted a chart from a...

    Gar

    not cool

    i posted a chart from a utility website showing 2X fault current. I’m always a life long learner although when the teacher is not nice, it makes it more challenging.
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    5$$
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    You said the 4160V gear is already in the room...

    You said the 4160V gear is already in the room with the (2) chillers. Why would the addition of a transformer make the replacement of one of the chillers make it a problem?
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    51$$
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    23168 I suspect the L-G fault current is 2X...

    23168
    I suspect the L-G fault current is 2X because you are dealing with only half the split phase winding, and only half of the impedance, but still all of the primary fault current as the primary...
  22. Are these actually 700 or 701 loads? Actually...

    Are these actually 700 or 701 loads? Actually Emergency or Legally required?

    Actually even if 702 loads, the code requires the transfer to be suitable for the indented use and designated and...
  23. Replies
    8$$
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    As additional info, I have found that when the...

    As additional info, I have found that when the AHJ makes a code reference for egress lighting levels, it is usually to the adopted building code first and if it doesn't have a reference, then they go...
  24. Replies
    8$$
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    Exit signs...

    Exit signs
    https://forums.mikeholt.com/showthread.php?t=184338

    For exit lights, it is based on the design of the light fixture and having the code required amount of FC on the floor.
  25. Thread: Battery Cables

    by ron
    Replies
    4$$
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    589

    Use DLO that is also RHH insulation rated. RHH...

    Use DLO that is also RHH insulation rated.
    RHH is a recognized insulation type and can be found
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