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  1. #1
    Join Date
    Mar 2007
    Location
    Western Montana
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    261

    Default Bonding ground to service neutral at mast?

    4-unit motel in a rural area, a real do-it-yourself haven. Original construction in 1938, significant remodel and conversion to 4plex in the 60's, then more stuff since (but that is another story). Wiring is mostly all ungrounded ragwrap, and the service panels don't seem to even offer a grounding terminal.

    I see what appears to be a system grounding conductor at the top of the service masthead that is attached to the service neutral. The grounding wire then runs down inside the metal mast to a metal raceway, and then THROUGH the center service panel. I cannot see any actual bonding connection inside the raceway, or inside the service panel. The grounding wire then disappears behind the metal exterior siding (both under the electrical panel, and at the top behind the top of the mast head).

    QUESTION: I think I can see some twisted logic in the intention (even though I never see the wire physically bonded to anything). But, can, or should, a grounding conductor attach (bond) to the service neutral ????
    Or, does any of this make any sense at all?

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  2. #2
    Join Date
    Mar 2007
    Location
    Chicago, IL
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    2,797

    Default Re: Bonding ground to service neutral at mast?

    Can't say what it's "for", and it may have been easier to see in person, but it appears to me that it would not a have been hard to miss the extra conductor at the weather head - nice reminder to look closely at everything, and not see only what you expect to,

    Michael Thomas
    Paragon Property Services Inc., Chicago IL
    http://paragoninspects.com

  3. #3
    Join Date
    Mar 2009
    Location
    Colorado Front Range
    Posts
    601

    Default Re: Bonding ground to service neutral at mast?

    Part of the answer to your question is that the service neutral winds up being grounded in a properly wired installation. Most frequently the neutral and all the grounds come together in one spot at the service disconnect.

    In the setup you seem to have the neutral is grounded at the mast. The neutral, also serving now as an equipment ground, is bonded to the meter/disconnect at the neutral connection in the housing.

    The gutter should also have a lug where the ground is attached to bond it to the rest of the system, and the nipples from the gutter to each of the meter/disconnects should each have a bonding bushing and connection to the ground wire.

    For the short distance from the top of a mast to the neutral buss in a service disconnect the neutral wire can serve as the neutral, equipment ground, and electrode grounding conductor. Just depends on how things are set up.

    All of this is is with the assumption that the ground wires that disappear eventually wind up at grounding electrodes. In this case, if metallic water lines are present they would need to be used. An additional grounding electrode is required if a water line is used as one, and this is typically, but not required to be, a ground rod.

    Missing here is info on the bonding of the gutter and nipples, and where the disappearing ends of the ground wires end up. Also a problem is the split bolt the ground at the top of the mast is attached to - it is missing a seperator bar to keep the aluminum and copper apart in the connection.


  4. #4
    Bob Winchester's Avatar
    Bob Winchester Guest

    Default Re: Bonding ground to service neutral at mast?

    Violation #1 and most obvious is the copper and aluminum connection together at the service mast in the pictures.
    Violation #2 is the parallel conductors that are not done according to NEC guidelines. This bare grounding conductor passes down the pipe with the service conductors to the meter socket and chances are it goes to something in the trough or meter sockets or service disconnects where the neutral is already bonded to ground. The rest of the information on grounding and bonding is missing. There are more than likely many more violations that were not allowed when this service was built in whatever year that was. Part of this falls under grounding and part of it falls under bonding and this is where most people lump it all together and screw things up. If you write this up incorrectly you will have a bigger mess on your hands. Simply say service grounding and bonding are illegal and be done with it. Without looking inside the meter sockets and the rest of the parts of the service you can not pick and choose very well and you chance making yourself look bad. If you try to include everything and leave something out there goes the egg on your face. There could be 5 or more violations here but we don't know enough to tell. Cutting the seal on the meters is not the best idea because only qualified personnel are allowed to do so.
    The metal nipples from the meter sockets to the trough can only be bonded at one end. When you bond both ends you make another parallel conductor problem that violates the NEC. There are books on bonding and grounding if this is all very confusing to you. There are experts to ask as well.


  5. #5
    Join Date
    Mar 2009
    Location
    Colorado Front Range
    Posts
    601

    Default Re: Bonding ground to service neutral at mast?

    The metal nipples from the meter sockets to the trough can only be bonded at one end. When you bond both ends you make another parallel conductor problem that violates the NEC.

    It is virtually impossible to eliminate all parallel paths unless you prohibit metal nipples. While only one end of the nipples are required to be bonded, the fact is that the locknuts used on the other end are permitted to provide the ground connection in most applications (the nipples on the service side require a bonding bushing or similar on one end)- meaning the connection you seem to think is prohibited is still there. Adding a bonding bushing on the other end does absolutely nothing to the situation except provide a better connection on that end. Anbody that's ever built an electrical service knows some of the neutral current winds up flowing through the enclosures - it's impossible to eliminate all of it without installing an insulator of some kind.

    Depending on where and when this was done, and the utility involved, this may have been the "required" way of doing things at the point in time it was done. And, I suspect, the utility may have been the only "say so" entity in existance at construction time.


  6. #6
    Join Date
    Mar 2007
    Location
    South-West Michigan
    Posts
    469

    Post Re: Bonding ground to service neutral at mast?

    Incorrect as-is, based on the photos. More disconcerting is the evidence of arcing at the sharp bend in the service hot conductor in the (last?) photo.

    Randall Aldering GHI BAOM MSM
    Housesmithe Inspection
    www.housesmithe.com

  7. #7
    Bob Winchester's Avatar
    Bob Winchester Guest

    Default Re: Bonding ground to service neutral at mast?

    Bill,
    You just don't bond the 2nd end of the nipple and since concentric knockouts don't count they do not constitute a bonding path. We are worried about code compliance when it comes to bonding. Personally I always use PVC nipples in a case like this but metal nipples are not a violation. Bonding both ends is however. I've seen the bonding conductor run through the nipple to the other end and then terminated in the 2nd enclosure. This used to be the norm in Grand Rapids Michigan but now they finally figured it out. I can't tell you how many violations I've written on this one matter over the years. I think they finally got it. Maybe I did fix stupid in that case. lol
    Talk about current taking another path other than the neutral conductor, every service with a grounding electrode system bonded to the neutral in compliance with the NEC or IRC produces some stray voltage since there is another grounding electrode at the transformer and neutral is bonded there. The code requires the grounding and it is where stray voltage comes from but we still do it that way because the code says so. Change all 3 wire service entrancees to 4 wire and we could eliminate the stray voltage caused here. Then if we lost a neutral in the trees another problem would arise. We would have much more loss due to voltage imbalance from the broken neutral. It's not perfect but it's the best we have to go with at this time.
    This became a deep discussion in a home inspector forum. Pardon us for getting so technical.


  8. #8
    Bob Winchester's Avatar
    Bob Winchester Guest

    Default Re: Bonding ground to service neutral at mast?

    Good observation Randy. Also the feeder from this breaker MUST be 4 wire. We haven't even started in on the entire installation, just the copper wire connecting at the mast.
    After the breaker is a feeder, it's no longer a service conductor. The burn in the enclosure would get me to turn the service off the main breaker and demand an upgrade here in Michigan. Inspectors have that authority when something is not kept in good repair and a danger is spotted. If the owner turned the breaker back on and ignored the demand for upgrade then the entire service could be shut off by the utility. We have to protect the idiots out there.


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