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  1. That's true, but there's still a high impedance...

    That's true, but there's still a high impedance connection to ground in the inverter.



    They can and do, in the pre-operation Riso test.
  2. Yes. If you rely just on electrodes you could...

    Yes. If you rely just on electrodes you could compromise the effectiveness of the GFDI. The bonding jumper between electrodes would probably also provide effective ground-fault detection, but in...
  3. FWIW, you are completely wrong. :p First of...

    FWIW, you are completely wrong. :p

    First of all, the pre-operation test (Riso) performed by TL inverters measures the resistance between each conductor and ground, as explained at 2:30 in this...
  4. An EGC to the inverter is still required to make...

    An EGC to the inverter is still required to make sure that the GFDI detects ground faults on the array. There has to be an adequate path for fault current in order for a fault to be detected.

    To...
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    If the inverter requires a neutral, then I don't...

    If the inverter requires a neutral, then I don't see why you wouldn't run a neutral to the disconnect and bond it there. It's the same as what would be done for all other service disconnects of any...
  6. First of all, your drawing doesn't show an EGC...

    First of all, your drawing doesn't show an EGC connection between the array and the inverter. This is a serious problem for the functioning of the ground-fault protection device in the inverter and...
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    And it is the fault we are worried about with...

    And it is the fault we are worried about with respect to an effective ground fault pathway.
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    What is the overcurrent protection on the line...

    What is the overcurrent protection on the line side of that disco? There is none (or rather, it's whatever is on the utility transformer).

    The available fault current on each side of that...
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    It does work, but countries that do it don't rely...

    It does work, but countries that do it don't rely on homeowners. See below.



    I think the point applies to any countries that wire dwelling units with TT systems. So apparently Japan, France,...
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    Yes, maintenance adds to expense. So does...

    Yes, maintenance adds to expense. So does quality control at the factory. So I think you are just repeating part of what I said in a roundabout way. As for OCPDs, there have been some threads here...
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    I made my comment because I didn't think your...

    I made my comment because I didn't think your explanation was very complete. I'd say it is the same thing, electrically, as far as I'm concerned. I'd only agree that the intentionally grounded...
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    So instead we intentionally build in the same...

    So instead we intentionally build in the same thing, just at 120V instead of 240V? :huh:
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    I think he meant what he said. Read it again. ...

    I think he meant what he said. Read it again.



    You really can't ever assume that loads will be consistently there, so under no circumstance could you ever have backfed supply that exceeds the...
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    That comment was addressing the last part of his...

    That comment was addressing the last part of his question, namely why 120% and not some other (higher) number.



    Yup. 8-)
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    I concur that this is 100% correct. If the...

    I concur that this is 100% correct.



    If the bus rating is equal to or greater than the sum of all sources of power, then he is correct. If the rating is not equal, then he is not correct and...
  16. Thread: PV LOTO

    by jaggedben
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    None of that really concerns the NEC or seems to...

    None of that really concerns the NEC or seems to be relevant to the original subject of this thread.

    I will just add that California has pretty good guidelines on fire setbacks and at this point...
  17. Thread: 705.12(C)

    by jaggedben
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    The section is clearly written with the intention...

    The section is clearly written with the intention of applying to large facilities where parts of the distribution on the load side of the legal service point may resemble a utility distribution...
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    600V RMS DC is just 600V DC.

    600V RMS DC is just 600V DC.
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    (Or to put it another way...) Yes it is. ...

    (Or to put it another way...)



    Yes it is. The NEC does not generally distinguish between AC and DC for voltage and current ratings. And 690.31 explicitly approves all wiring methods in the...
  20. Thread: PV main

    by jaggedben
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    Well, take a look at 705.32.

    Well, take a look at 705.32.
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    Voltage sensing on the neutral is required by...

    Voltage sensing on the neutral is required by most inverters. 3 phase meters measure the neutral current, single phase meters do not, but I think that's irrelevant to the subject here.

    A...
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    For calculating line currents, see this article:...

    For calculating line currents, see this article:
    http://solarprofessional.com/articles/design-installation/calculating-3-phase-line-currents?v=disable_pagination

    It's not simple math for an...
  23. Thread: PV LOTO

    by jaggedben
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    Is the main concern that the fire department...

    Is the main concern that the fire department would refuse to fight a fire on the building?

    If so, I think the solutions would be...

    1) Install a DC disconnect close to the array.
    2) Educate...
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    I don't think I've ever heard of an inverter that...

    I don't think I've ever heard of an inverter that had an N=G bond at the inverter. I'm pretty sure that would violate a UL standard, at least for utility interactive inverters. (There might be some...
  25. I agree that if the conductors supplying the...

    I agree that if the conductors supplying the combiner are a feeder, then no neutral is required.

    If the conductors are service conductors, then it may be a highly debatable question. One of the...
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