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  1. #1
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    Default Neutral bonding in multiple units

    This is new construction, a mid-sized home with a legal basement suite. Two meters and two 100 amp Eaton service panels. I called for the electrician to check for a bond of the neutral bus to the panel in both of these 100 amp service panels. I was looking for a strap from the back of the panel to the neutral bus. There is no long screw from the bus to the panel. The conduit is PVC.

    Am I missing something, new design or what?

    Under what circumstance in a duplex with two meter boxes, would one panel have neutral bonded to the panel and the other not bonded? Or must both always be bonded.

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    John Kogel, RHI, BC HI Lic #47455
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  2. #2
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    Default Re: Neutral bonding in multiple units

    Are they both service panels or one service feeding another panel?

    The wiring diagram will show the location of the bond screw or strap.

    All answers based on unamended National Electrical codes.

  3. #3
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    Default Re: Neutral bonding in multiple units

    You area in Canada and things are slightly different there, but ... if that were 'down here' ...

    The two separate disconnects would be required to be grouped together (they may be, you did not say either way), with some exceptions to that.

    Likewise, only one service is permitted to one structure, so I am wondering if there is another service somewhere.

    Another reason I say that is that you always show panels with extra dividers between the service section and the panel section and that is not present in either panel, plus both panels have 4-wire service entrance/feeder conductors - another reason to suspect they are not actually the service equipment.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  4. #4
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    Default Re: Neutral bonding in multiple units

    One service mast, two meters, no disconnects outside here in the frigid and frugal North.

    The two main breakers pictured are the two service disconnects. The first 2 pics depict the upper unit service panel, which is in the garage below that unit. The 3 and 4th pics show the suite panel, which is on the same wall but the other side of that wall in the suite.

    The dividers plates separating the main breaker from the branch circuits in the Canadian service panel are removed in the pics. I looked for a bonding screw in at least one of those service panel.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  5. #5
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    Default Re: Neutral bonding in multiple units

    I will post pics to prove it when I get back to the other HD. One service drop, one mast. Mast entering the top of the left meter can, which is marked Unit A. Unit B meter is to the right.
    Two meter cans in contact with each other at the base of the mast, no disconnect.
    In the garage, a 100 amp panel, that's in Unit A. The label shows a 'ground'ing screw, if present would be at the lower end of one of the neutral buses. The only screw there is the shiny short one in the pic, which is a short one that connects the two neutral bus bars. No it does not contact the back of the panel box. Did I say it is a short one?

    Unit B, the suite, panel is in a bedroom behind the garage. No bonding screw on either neutral bus. I know this is wrong and feel more sure of it now.

    My question then is this - the service conductors split ahead of the meters, of this I am certain. People in Unit A pay only for their share of the usage. The meters are not daisy-chained. No disconnect out there, either.
    Should the neutral bus be bonded to the panel box in both panels ? I believe so and I believe the boss will be fixing this, if he hasn't already.

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    Last edited by John Kogel; 08-03-2014 at 10:20 PM.
    John Kogel, RHI, BC HI Lic #47455
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  6. #6
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    Default Re: Neutral bonding in multiple units

    The pics don't show on my tablet, but it sounds like two services just fed by one set of service conductors.

    All answers based on unamended National Electrical codes.

  7. #7
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    Default Re: Neutral bonding in multiple units

    John,

    The photo of the label is blurry, but what is that black dot above the right neutral terminal bar showing, where the neutral is bonded to the enclosure/ground?

    No need to take more photos to "prove" what you are describing, I was asking questions so I could visualize what you had there.

    There is one service to the building (one service drop to both meters) - that is good.

    There are allowed to be as many meters as one wants, however, there are only allowed up to 6 main service disconnects, and there are only 2 main service disconnects there - that is also good.

    There should be one set of service entrance conductors from one meter to its service equipment, and another set of service entrance conductors from the other meter to its service equipment - we can only presume that to be the case.

    The service entrance conductors to each service equipment requires that the neutral be bonded to ground at the service equipment, that may be that black dot above the right neutral terminal bar? Otherwise, the neutral should be bonded to ground somewhere in there.

    The location of the disconnects is not good by our NEC, not sure how the CEC addresses this:
    - 230.72 Grouping of Disconnects.
    - - (A) General. The two to six disconnects as permitted in 230.71 shall be grouped. Each disconnect shall be marked to indicate the load served.
    - - - Exception: One of the two to six service disconnecting means permitted in 230.71, where used only for a water pump also intended to provide fire protection, shall be permitted to be located remote from the other disconnecting means.
    - - (B) Additional Service Disconnecting Means. The one or more additional service disconnecting means for fire pumps, emergency systems, legally required standby, or optional standby services permitted by 230.2 shall be installed remote from the one to six service disconnecting means for normal service to minimize the possibility of simultaneous interruption of supply.
    - - (C) Access to Occupants. In a multiple-occupancy building, each occupant shall have access to the occupant’s service disconnecting means.
    - - - Exception: In a multiple-occupancy building where electric service and electrical maintenance are provided by the building management and where these are under continuous building management supervision, the service disconnecting means supplying more than one occupancy shall be permitted to be accessible to authorized management personnel only.

    If the CEC is like the above, the two disconnects on opposite sides of the wall is a problem.

    Here is another thing to consider - the service entrance conductors now provide two paths back to the meter: the neutral conductor and the ground conductor, if one is loose or not bonded to the other, there is a loss of that path. Additionally, being as those are service entrance conductors, one being insulated and one being bare, and the bare conductor appearing to be smaller than the insulated conductor, and those conductors are in parallel ... they don't meet the requirements for parallel conductors.

    Hopefully, Jim will add more to that.

    I forgot to ask - what's with the house in the background of the photo showing the masts? And what's with the insulator on the mast of the house you are one?

    On the house in the background, what is connected to that insulator and where does it go - it goes to the other mast? There is a similar unused mast on the house you are on, will it be done the same way?

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  8. #8
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    Default Re: Neutral bonding in multiple units

    The neutral is commonly smaller than the hots, especially in a service cable. Even the calculations have an adjustment for the reduced neutral since some circuits like straight 240 does not need a neutral.

    If the meter contains the grounded as well as the grounding conductor this is the one spot that parallel paths are allowed or tolerated.

    All answers based on unamended National Electrical codes.

  9. #9
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    Default Re: Neutral bonding in multiple units

    Thanks, J & J.
    The black object on the label is a bonding screw which I searched for and did not find in either panel. I thought they might be concealed but of course the manufacturer would not conceal them. It is usually a bold brass screw.

    We do not have the requirement to group the discos together. And the disconnects are always indoors out of the weather.

    The insulator and second weatherhead is simply for cable TV and Internet. I had to tell my clients that too. "Don't worry about that.The cable guy will do the hook up when you move in."

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  10. #10
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    Default Re: Neutral bonding in multiple units

    PS, notice how tidy everything is in those panels? That is the standard.
    The authorities here don't allow sloppy work.

    Per the CEC, grounding and grounded are separated.
    Service and branch cicuits are separated.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  11. #11
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    Default Re: Neutral bonding in multiple units

    Here is the rule, here in this part of Canada.

    Duplex with a double meter can, that is one service mast, two meters side by side in one enclosure, the neutral is grounded, connected to the grounding conductor, in the meter base, not in the breaker panel.
    The two breaker panels are wired as s^bpanels, so that is why there is no bonding of the neutral bus in those panels.

    My house is a single family with a suite, but it is wired as a duplex, The two meter cans are joined so treated as one. No disconnect. Only in Canada.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

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