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Thread: Why is a sub*panel not "effectively" bonded when connected to main panel by emt?

  1. #11
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    Quote Originally Posted by drcampbell View Post
    Single-point grounding prevents many, many problems. Not just in buildings, but also in vehicles, boats, aircraft, audio-video, concert stages ... almost everywhere electricity is used.
    Rock star pastor is electrocuted as he conducts baptism service
    FYI: http://www.religionnewsblog.com/1452...ues-contractor. (The contractor who built the baptistry and specifically installed the heating elements.)

  2. #12
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    This is exactly why I asked this question

    Quote Originally Posted by LarryFine View Post
    To put it simply, at no point beyond the point in the main disconnect (usually) where the EGC system (enclosures, GECs, etc) is bonded to the neutral, should the neutral ever be grounded again. It should be insulated from anything grounded as if it were an energized conductor.
    I appreciate that the neutral and ground should never be bonded beyond the main disconnect and that is why I asked this question. I know that NEC allows bare ground wire in EMT conduit, but in this case the bare copper "ground" connects the neutral bars in the main panel and the sub-panel. Common sense tells me that at some point, this bare copper ground has to "short" against the EMT conduit, creating a second (or more) point of connection between the neutral and grounding systems. If this concern is correct, am I better off having the electrician: a) remove the bare copper wire between the neutral bars in both panels or b) leave the bare copper wire, but change the connection to the grounding bars in both boxes? At this time there is no grounding bar in the sub-panel as all circuit grounds are run to the bonded neutral bar in the main panel. I asking for advice as I work in an area with no building inspectors to rely upon, and I would like to ensure that I am building a safe house. Thanks!

  3. #13
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    Quote Originally Posted by cowdr4 View Post
    I appreciate that the neutral and ground should never be bonded beyond the main disconnect and that is why I asked this question. I know that NEC allows bare ground wire in EMT conduit, but in this case the bare copper "ground" connects the neutral bars in the main panel and the sub-panel.
    Are you saying the EGC's are landed on the neutral bar in the "sub-panel?

    Quote Originally Posted by cowdr4 View Post
    Common sense tells me that at some point, this bare copper ground has to "short" against the EMT conduit, creating a second (or more) point of connection between the neutral and grounding systems.
    It doesn't matter, the EGC's (copper wire and EMT) are going to be tied together at each end anyways. How is this going to create a second connection to the Neutral.

    Quote Originally Posted by cowdr4 View Post
    If this concern is correct, am I better off having the electrician: a) remove the bare copper wire between the neutral bars in both panels or b) leave the bare copper wire, but change the connection to the grounding bars in both boxes? At this time there is no grounding bar in the sub-panel as all circuit grounds are run to the bonded neutral bar in the main panel. I asking for advice as I work in an area with no building inspectors to rely upon, and I would like to ensure that I am building a safe house. Thanks!
    The neutrals and EGC's must tie together in the service equipment (main Panel or disconnect) and they must be isolated in the sub-panel.



    Roger
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  4. #14
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    Quote Originally Posted by cowdr4 View Post
    I appreciate that the neutral and ground should never be bonded beyond the main disconnect and that is why I asked this question. I know that NEC allows bare ground wire in EMT conduit, but in this case the bare copper "ground" connects the neutral bars in the main panel and the sub-panel. Common sense tells me that at some point, this bare copper ground has to "short" against the EMT conduit, creating a second (or more) point of connection between the neutral and grounding systems. If this concern is correct, am I better off having the electrician: a) remove the bare copper wire between the neutral bars in both panels or b) leave the bare copper wire, but change the connection to the grounding bars in both boxes?At this time there is no grounding bar in the sub-panel as all circuit grounds are run to the bonded neutral bar in the main panel. I asking for advice as I work in an area with no building inspectors to rely upon, and I would like to ensure that I am building a safe house. Thanks!
    Reply to blue: That conductor should be insulated (and identified with white or gray color that designates it as a grounded conductor) so it can't make inadvertent contact with non current carrying conductive components.

    Reply to red: They should probably have installed a grounding bar in the second panel and landed those conductors there.

    Though the enclosure for a panelboard is technically called a cabinet, 250.148 more less says if those grounding conductors pass through a box - they need to all bond to one another and to the box. Not sure where your circuits come to. If they enter the first panel but not enough spaces and you had nipple to the second panel to get them to a breaker, then landing those grounds in the first panel isn't a problem. If they pass through the second panel we then must question whether 250.148 is supposed to apply here as well. Most people would put a ground bar in the second panel and land them there though with little additional thought about it.


    ‚ÄčIs there neutral conductors landed on the neutral bus of the second panel?
    I live for today, I'm just a day behind.

  5. #15
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    Quote Originally Posted by cowdr4 View Post
    I appreciate that the neutral and ground should never be bonded beyond the main disconnect and that is why I asked this question. I know that NEC allows bare ground wire in EMT conduit, but in this case the bare copper "ground" connects the neutral bars in the main panel and the sub-panel. Common sense tells me that at some point, this bare copper ground has to "short" against the EMT conduit, creating a second (or more) point of connection between the neutral and grounding systems. If this concern is correct, am I better off having the electrician: a) remove the bare copper wire between the neutral bars in both panels or b) leave the bare copper wire, but change the connection to the grounding bars in both boxes? At this time there is no grounding bar in the sub-panel as all circuit grounds are run to the bonded neutral bar in the main panel. I asking for advice as I work in an area with no building inspectors to rely upon, and I would like to ensure that I am building a safe house. Thanks!
    The subpanel needs a separate ground bar. The bare #6 needs to land on this instead of the neutral bar. You seriously need to get the electrician to check this or get another electrician.
    If you aim at nothing, you will hit it every time!

  6. #16
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    ECG lands on neutral bar in sub-panel

    Quote Originally Posted by roger View Post
    Are you saying the EGC's are landed on the neutral bar in the "sub-panel?

    It doesn't matter, the EGC's (copper wire and EMT) are going to be tied together at each end anyways. How is this going to create a second connection to the Neutral.


    The neutrals and EGC's must tie together in the service equipment (main Panel or disconnect) and they must be isolated in the sub-panel.
    Roger
    1. Yes, the bare so-called (by the electrician) "ground" wire from main to sub-panel connects to the neutral bar in the sub-panel.
    2. Concern in this case is that the EGC is tied into the neutral bar in sub-panel, which will "short" against EMT creating a second connection between neutral and EGC.
    3. Sounds like I need to have the electrician remove this wire.

  7. #17
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    Quote Originally Posted by cowdr4 View Post
    3. Sounds like I need to have the electrician remove this wire.
    I agree and will add that it would be money well spent to hire an independent inspection service to inspect the whole job, the cost isn't that much for peace of mind.

    Roger
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  8. #18
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    I think the question has been effectively answered. It's getting to the point that it's hard to answer any further without getting into DIY. So I am closing the thread.
    I recommend getting the electrician to check this or if he doesn't agree, get another one that knows the code.
    If you aim at nothing, you will hit it every time!

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