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Thread: Backfeeding via multiple subpanels

  1. #11
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    (Sigh)

    It has essentially nothing to with PG&E owning the meter, and certainly nothing to do with the NESC. The disco requirements come from PG&E's PUC-approved interconnection agreement for a generating site. Otherwise it would be entirely up to the AHJ.

    But yes, clarify the PG&E requirements before getting the permit, if you can.

  2. #12
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    Quote Originally Posted by jaggedben View Post
    It has essentially nothing to with PG&E owning the meter, and certainly nothing to do with the NESC. The disco requirements come from PG&E's PUC-approved interconnection agreement for a generating site. Otherwise it would be entirely up to the AHJ.

    But yes, clarify the PG&E requirements before getting the permit, if you can.
    Doesn't the utility req. for a PV disco adjacent to the meter come from the NESC?

    The utility wants to be able to disconnect the PV system from the meter, when there is a main breaker with the meter, sure the PV is technically "off" when you close the main, but there are still potentially live wires coming from the PV into the cabinet. Hence the common sense of having a switch or 3 adjacent to the meter main so the utility worker *knows* the PV is not connected.

    If there is/are no PV disco adjacent to the meter main, you have a load side connection with breakers elsewhere.

  3. #13
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    Quote Originally Posted by PVfarmer View Post



    Actually, it's a matter of PG&E owning the meter.
    I say their jurisdiction ends at the meter main load side breaker terminals.
    The utility absolutely has a say in what you can connect to their system and what you can't if it is capable of backfeeding the grid. I deal with this stuff all day, every day.

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    Quote Originally Posted by ggunn View Post
    It's not a code issue, it's a matter of what the AHJ wants, and different AHJ's want different things.

    The utility absolutely has a say in what you can connect to their system and what you can't if it is capable of backfeeding the grid.

    I deal with this stuff all day, every day.
    I find these two statements totally contradictory.
    The OP's building inspector isn't going to explain what PG&E *requires*.

    And no utility makes up special requirements, they have greenbooks.
    Here is PG&E's, the reason why you can't do what the OP is proposing may be in here.
    https://www.pge.com/en_US/business/s...al-online.page

    But I still think it's as simple as: there are no 400A breakers rated for 3 sets of conductors.

    Have you seen a 400A breaker with that capability in your everyday dealings?

  5. #15
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    KG808/OP-
    There may be some relevant info here, the first two links should be pdfs from Eaton.
    https://www.google.com/search?q=appl...s+molded+eaton

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    Quote Originally Posted by PVfarmer View Post
    Doesn't the utility req. for a PV disco adjacent to the meter come from the NESC?
    I don't think so, but instead of speculating about where PG&E's requirements come from, why not get them straight from the horses mouth. I regret not posting that link earlier.

    The utility wants to be able to disconnect the PV system from the meter, [/QUOTE]

    What I think they care about is disconnecting the PV system from their grid in the unusual case where a backfeed causes problems. They care less whether the PV system stays connected to the load side of the meter. A smart meter with a shutoff capability is one way they can meet their needs without requiring a discreet disconnect. But those don't come rated more than 320A. (I believe that's 320A continuous, so a 400A rated panel may still qualify, but I could be wrong and that's where the actual text of the panel label or a letter from a manufacturer will determine the outcome.)

  7. #17
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    Quote Originally Posted by PVfarmer View Post
    But I still think it's as simple as: there are no 400A breakers rated for 3 sets of conductors.

    Have you seen a 400A breaker with that capability in your everyday dealings?
    Quote Originally Posted by PVfarmer View Post
    KG808/OP-
    There may be some relevant info here, the first two links should be pdfs from Eaton.
    https://www.google.com/search?q=appl...s+molded+eaton
    Not relevant or helpful to the OP. 400A main could be feeding a panelboard which feeds all three subpanels, or any of several other arrangements. There's no reason to believe the OP has a problem with the equipment on site, that would be a whole other thread. Keep it on topic.

  8. #18
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    Quote Originally Posted by jaggedben View Post
    400A main could be feeding a panelboard which feeds all three subpanels, or any of several other arrangements.
    You'd rather argue with me than read- why?
    Not reading their comments is...
    "Not relevant or helpful to the OP."

    I already suggestested the italicized back in comment #3. The OP did not say "oh we already have that", so...where'd you get it from?

    Quote Originally Posted by Kg808 View Post
    Option A: Ground mount all of the panels and just back feed straight to the main.

    I have tied my backfeed OCPD into many sub panels before. But never ran into this situation to use multiple roof spaces and sub panels to backfeed one main/meter.

  9. #19
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    Quote Originally Posted by PVfarmer View Post
    Not reading their comments is...
    "Not relevant or helpful to the OP."
    Being an inexperienced person who doesn't know how to read their vocabulary is what's not helpful. "just back feed straight to the main" has meant the main panel, most of the hundreds of times people have said to me in the course of my work. It does not imply a supply side connection. But even if I'm making a wrong assumption there, it's off topic. The OP just asked if an AHJ will allow multiple PV sources to be connected at various locations. Line or load side at the main makes no difference to the answer to his question.

  10. #20
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    Ok... let's all play nice huh? you guys are going back and forth on semantics here. I understand I could've been a little more clear with my wording on my OP.

    Pv farmer: I understand why you're concerned about 3 load side terminals on a main breaker. It's a 400a panel with a 200A split. 200A main feeding straight to the main house sub panel and a 200A main with attached 12/24 space distribution at the main panel. With 2 100 A breakers feeding sub panels at the other 2 structures.

    and yes the main concern I had was wether or not I could mount on 3 separate buildings for the same pv system. Sorry if I over complicated it. The ampacities of the panels and breakers were just for a better picture of the system as a whole.

    All these replies have been great help though. PGE has responded and said they have no problem with it as long as the signage is clear. Waiting on response from the AHJ.

    Thanks again for the help.

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