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  1. Replies
    11$$
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    386

    I think that he means that the probability of a...

    I think that he means that the probability of a random arc flash event happening while the guys are sitting there is non-zero.
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    5$$
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    159

    Is 6W DC STC even enough to overcome the...

    Is 6W DC STC even enough to overcome the self-discharge of the battery?
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    130$$
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    4,982

    I once caught a "friend" of mine who was...

    I once caught a "friend" of mine who was pilfering from me that way. I painted the surfaces of some of the spots that were being hit with a silver nitrate solution and watched for the black stains on...
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    72$$
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    2,117

    That's what I thought. Could that be the source...

    That's what I thought. Could that be the source of the current the OP is seeing?
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    72$$
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    2,117

    CAVEAT: I just wandered into this discussion, I...

    CAVEAT: I just wandered into this discussion, I haven't read every entry, and it's not in my normal bailiwick, but I have a general question:

    If the secondary side of the service transformer has...
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    12$$
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    412

    Relax. Of course my designs are all well equipped...

    Relax. Of course my designs are all well equipped with ECG conductors. I am not an expert on internal inverter design, but the way ground fault detection has been explained to me by the manufacturers...
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    12$$
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    412

    FWIW, many inverters are now transformerless and...

    FWIW, many inverters are now transformerless and do not (cannot) use the EGC to detect ground faults.
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    43$$
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    768

    If it does nothing else, this discussion supports...

    If it does nothing else, this discussion supports my point that this should be expressly and explicitly addressed in 690 and/or 705. If it's this controversial (and it is), the code writers should...
  9. Replies
    43$$
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    768

    It's never going to happen. We are limited to the...

    It's never going to happen. We are limited to the size of the service with a supply side interconnected PV system.

    Still reading the rest of your response...
  10. Replies
    12$$
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    412

    Is the DC side grounded or ungrounded? It makes a...

    Is the DC side grounded or ungrounded? It makes a difference; inverters for ungrounded systems do not (cannot) use reference to ground to detect ground faults.
  11. Replies
    5$$
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    282

    Typically you cannot use a 480V delta primary...

    Typically you cannot use a 480V delta primary because the inverter needs the neutral as a voltage reference. I have been around this tree a few times; originally I was counseled by an inverter FAE to...
  12. Replies
    43$$
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    768

    But it does. I have always run the EGC from the...

    But it does. I have always run the EGC from the PV system back through (and bonded to) the disco to the source. I have always sized it for the OCPD of the disco, but as I have found if I had sized it...
  13. Replies
    43$$
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    768

    That has been a concern to me with line side PV...

    That has been a concern to me with line side PV taps to a service where the tap is an order of magnitude or more smaller than the service. I don't see where even tying the neutral to ground in the...
  14. Replies
    43$$
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    768

    I do not disagree in principle, but what are...

    I do not disagree in principle, but what are those requirements if they are more than what is in Table 250.66? As I said, whether you consider it an EGC sized to the OCPD of the disco via Table...
  15. Replies
    12$$
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    412

    One thing about your drawing, and I don't know if...

    One thing about your drawing, and I don't know if it is germane, is that in the inverter all the grounds are (usually, anyway) tied together. Your drawing shows isolation between the EGC and the GEC...
  16. Replies
    43$$
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    768

    I get that, but looking at Exhibit 250.30 in the...

    I get that, but looking at Exhibit 250.30 in the 2011 NEC Handbook, it shows two taps in parallel on a service drop, one with #3 current carrying conductors and one with 3/0 CCC's. The ground wire is...
  17. Replies
    43$$
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    768

    With PV, which is the load end? Current flows one...

    With PV, which is the load end? Current flows one way under normal conditions and the other in the event of a fault. And according to the AHJ where I am, a supply side interconnection is not a tap,...
  18. Replies
    43$$
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    768

    I ran a few test cases and found little...

    I ran a few test cases and found little difference between EGC (250.122) and GEC (250.66) sizing for the same tap. Sometimes the GEC was one size larger, but sometimes the EGC was larger. Note that...
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    43$$
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    768

    Hmmm. I have designed and installed several...

    Hmmm. I have designed and installed several commercial PV systems in four different AHJs' territories with supply side taps and I have in all cases connected the EGC (sized for the OCPD in the disco)...
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    16$$
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    418

    You did, but phrased a bit differently. No biggie.

    You did, but phrased a bit differently. No biggie.
  21. Replies
    43$$
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    768

    OK, but in PV systems which are interconnected...

    OK, but in PV systems which are interconnected with a supply side tap, there is typically (always?) an EGC from the PV system through the disconnect back to the existing service sized to the OCPD in...
  22. Replies
    43$$
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    768

    Maybe (probably) I am not understanding you....

    Maybe (probably) I am not understanding you. Neutral and EGC pass through the disco back to the tap. Neutral and EGC are bonded in the service at or near the tap. All conductors are sized correctly....
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    43$$
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    768

    We have had debates on this in here, but really,...

    We have had debates on this in here, but really, what difference could it make? Typically the AC disco in a supply side tap is 10' or less as the wire flies from the tap point, and the neutral and...
  24. Nor in Texas.

    Nor in Texas.
  25. Replies
    14$$
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    462

    My mom had a dog that did that. The invisible...

    My mom had a dog that did that. The invisible fence did nothing but keep him from coming back in once he got out.
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