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  1. #1
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    Default 3-wire vs 4-wire

    This panel was fed by 3 wires from the service equipment. Service equipment (100A) at the outside garage wall; this new panel (60A) at the inside garage wall had the 3 wire feed. This new panel supposedly was recently installed and permitted. However, without a 4 wire feed... The panel itself is not grounded nor are any of the circuits grounded. The neutral is a floating neutral, and separated from the grounding bus bar. So there is no connection between neutral and ground... But how do they expect to achieve 'ground'...?
    Dunno -- am I missing something? DSC02627 (Small).JPG

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  2. #2
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    Thumbs down Re: 3-wire vs 4-wire

    Metal conduit from service panel to this secondary panel maybe? Without that , looks like they need a grounding conductor pulled in...

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    Alton Darty
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  3. #3
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    Default Re: 3-wire vs 4-wire

    Quote Originally Posted by Alton Darty View Post
    Metal conduit from service panel to this secondary panel maybe?
    While that would remove the issue, that looks like NM cable/SE cable and neither would be run in metal conduit, plus a grounding bushing would be required.

    Pulling in a grounding conductor isn't the correction needed, replacing that wiring with four-wire cable would be.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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    Default Re: 3-wire vs 4-wire

    AD & JP - thank you both. Your observations have clarified the picture for me. Those are the clues that I was missing. And I feel confident now about my recommendations to them about this panel.

    The service panel was a Sylvania/Zinsco that was packed so tight with wires that the cover could not be put on without pinching the wires. Also there was a little issue with original installer ganging together all of the neutral wires at the bus bar.DSC02616 (Small).JPG

    I appreciate your comments,
    thanks, Chris


  5. #5
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    Default Re: 3-wire vs 4-wire

    When I zoom in on the photo, it almost looks like there may be a grounding conductor with that cable as there are two NM cables to the right of it and looks to be three bare grounding conductors going to the left of that feeder cable - which would leave the question of: are there three grounding conductors and one is from the feeder; are there three NM cables to the right and I only see two; are there only two grounding conductors to the left of the feeder; and if there are three grounding conductors, is one larger than the other two (one looks to be larger, and looks to go over to the top left corner ... where it disappears and is no longer seen).

    I would verify as best possible that there was no grounding conductor from that feeder cable (sure looks like there is not), and I am sure that is what you did - and if no grounding conductor, then there is a problem.

    With the grounding conductors supposed to be run in the same conduit (or be the metal conduit), or be run in the same cable sheath, as the other conductors - there is no way to just 'add a grounding conductor to the feeder' ... that feeder cable would need to be replaced.

    Could you see through that small gap at the top of the panel and see it that was a connector for the NM feeder cable or if it was metal conduit (if metal conduit, it would solve one issue and potentially raise another issue).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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  6. #6
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    Default Re: 3-wire vs 4-wire

    I think I see the grounding conductor for the feeder in the 7th screw from the right. It should not have been hard to see the conductor emerging from the sheath while on site.

    - - - Updated - - -

    There are 6 breakers and 7 grounding conductors in the ground bar. The feeder and panel are correct.

    All answers based on unamended National Electrical codes.

  7. #7
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    Default Re: 3-wire vs 4-wire

    Quote Originally Posted by Jim Port View Post
    I think I see the grounding conductor for the feeder in the 7th screw from the right. It should not have been hard to see the conductor emerging from the sheath while on site.

    - - - Updated - - -

    There are 6 breakers and 7 grounding conductors in the ground bar. The feeder and panel are correct.
    Jim has better eyes than I do, and if I zoom in, I can see 6 NM cables (not counting the feeder cable), which would be 6 grounding conductors, and as Jim said, there are 7 grounding conductors in the ground bar, which leaves one for the feeder cable ... so that one I questioned at the top and to the left of the feeder cable must be the grounding conductor from the feeder.

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

  8. #8
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    Default Re: 3-wire vs 4-wire

    Gentlemen you are right. The grounding wire was somewhat hidden behind the NM cable. I didn't stop to count the numbers of ground wires versus the number breakers, but obviously that is the key.
    Again thank you for your observation, and pointing out what should have been obvious to me.
    Good lesson: Don't be hasty.
    Chris


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    Default Re: 3-wire vs 4-wire

    If you look at the top left knockout bushing, just after the trimmed insulator jacket, there appears to be thick twisted AL strand wire descending to the left. As the strand starts to descend it is wrapped with copper grounds.
    Am I imagining this?


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  10. #10
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    Default Re: 3-wire vs 4-wire

    Quote Originally Posted by ROBERT YOUNG View Post
    Am I imagining this?
    Yes.

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

  11. #11
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    Default Re: 3-wire vs 4-wire

    Looks like the light reflecting off the black conductor.

    - - - Updated - - -

    Looks like the light reflecting off the black conductor.

    All answers based on unamended National Electrical codes.

  12. #12
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    Default Re: 3-wire vs 4-wire

    Don't be hasty, don't be lazy, two good mottos.

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

  13. #13
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    Default Re: 3-wire vs 4-wire

    Quote Originally Posted by Jerry Peck View Post
    Yes.
    Well there goes that idea, shot full of holes.

    Robert Young's Montreal Home Inspection Services Inc.
    Call (514) 489-1887 or (514) 441-3732
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  14. #14
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    Default Re: 3-wire vs 4-wire

    Why all the 30A circuits in the Zinsco/Sylvania panel?


  15. #15
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    Default Re: 3-wire vs 4-wire

    There are only 2 - 30 AMP circuit breakers. One at the top and one at the bottom. The rest that look like that same green colored breakers are actually the pale blue 15 amp single breakers. May be faded by time... So goes the Zinsco.


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