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Neutral and Earth Ground Question

Discussion in 'Electrical Engineering' started by Peter, May 28, 2005.

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  1. Peter

    Peter Guest

    I have a question about house wiring.

    In my house, our earth ground (green) goes to a metal strip in the circuit
    breaker box and then out to a 10ft pole in the ground I believe?

    Other people are telling me that all the green wires should be tied to
    neutral in the fuse box.

    Is this true and/or where do I find out how the latest house wiring
    codes??? As in, what catagory would I search for???


    Thanks
     
  2. SQLit

    SQLit Guest

    Your looking for Services, article 230 in the NEC.

    Ground rods installed for residential are usually 8 feet long.

    Grounds and neutrals are always tied together at the service, (meter
    location). And separated every where else. Your vague as to the exact
    installation so definite answers are impossible.

    Assumption is that you reside in North America
     
  3. John Gilmer

    John Gilmer Guest

    Including the "main" CB box?

    EMWTK
     
  4. Fred

    Fred Guest

    The neutral conductor is grounded only once and at the main service entrance
    only..

    In Canada the neutral bar in a "service entrance panel" is grounded to the
    panel via a brass screw that bonds the neutral bar to the panel steel
    enclosure. The main ground conductor is also bonded to the panel metal
    enclosure. This brass screw in effect bonds the neutral bar to the main
    ground conductor. This screw is to be removed on sub panels connected to
    the main panel.

    Fred
     
  5. Bob Weiss

    Bob Weiss Guest

    Ground and neutral are bonded at the "main service disconnect". In
    most residential services, that is the main breaker in the panel, so the
    neutral is grounded inside the main panel. If the service includes an
    outdoor main disconnect switch, the neutral is bonded there, and kept
    separated downstream.


    Bob Weiss N2IXK
     
  6. John Gilmer

    John Gilmer Guest

    IOW: In your typical service CB box with a BIG breaker at the top, there
    isn't any difference between GROUND and NEUTRAL.

    (Well, maybe a little. If you run short of screws for grounds/neutrals you
    should double up on the groups but not on the neutrals.)
     
  7. John Gilmer

    John Gilmer Guest

    True. It's means that neutral and ground aren't under the same screw or in
    the same "hole." But otherwise, there isn't a separate buss for ground and
    neutral.
     
  8. daestrom

    daestrom Guest

    Maybe it's just me, but all the service panels I've been in (admittedly only
    a few), there are exactly as many holes in the neutral bar as there is in
    the ground-bus bar, and that number is more than the number of 'slots' for
    circuit breakers. So unless you have two circuits coming from every
    breaker, finding an empty hole for the neutral (in the neutral bus) and an
    empty hole in the ground bus (even when neutral and ground are not bonded
    such as a sub-panel) hasn't been all that much of a problem.

    The only problem I've ever had is when some jerk runs a whole series of
    circuits right over the top of a section of neutral bus so you can't get to
    the holes. But that's a different story.

    daestrom
     
  9. ehsjr

    ehsjr Guest


    If the bus bar is listed for the use (2 wires in the same hole)
    it's not a problem, so the "exception" is already built in. As
    far as solving the problem of not enough holes, just add another
    bus bar.

    Ed
     
  10. John Gilmer

    John Gilmer Guest

    ..
    Didn't someone already cite the NEC words that say that NEUTRALs don't
    "share." "Grounds" can share. I suspect that in many panels, the "next
    time" you modify or add a circuit, you consider "curing" these violations.

    Frankly, if you are running short of screws, you can alway "multiplex" your
    grounds by any one of a number of approved ways. If neutral and ground are
    already firmlybonded to the panel case, legal grounding can be just by
    bonding to the metal of the panel inclosure.

    A short term interruption of "ground" should not hurt anything whereas a
    short term interruption of neutral mgiht easily damage or destroy lots of
    expensive "stuff."
     
  11. The fact that the neutral carries current and is therefore subjected to
    thermal cycling. If not terminated in individual terminals the
    connection will loosen if the thermal cycling is not the same and of
    course it never would be.
     
  12. Roy Q.T.

    Roy Q.T. Guest

    From: Peter
    I have a question about house wiring.
    In my house, our earth ground (green) goes to a metal strip in the
    circuit breaker box and then out to a 10ft pole in the ground I believe?
    Other people are telling me that all the green wires should be tied to
    neutral in the fuse box.
    Is this true and/or where do I find out how the latest house wiring
    codes??? As in, what catagory would I search for???
    Thanks

    ------------->

    The neutral and grounding busses in your house, by your description are
    correct., people assume differing positions on grounding issues but the
    NEC is speciic on the matter., and the only place required to have the
    neutral and ground tied together as you say is at the Meter/Disconnect.

    If you have 2 isolated busses in your breaker panel (1)with the green
    wires & (1) with the white wires ) count yourself lucky you have a truly
    Bonded & Grounded Panel.

    You can find more about this subject if you look up " Bonding " in your
    search engine.

    In Excisting Bonded Residential Panels the Bonding & Neutral Buss Bars "
    Do Not Require Jumping " nor being connected to each other in any way ~
    that has already been negotiated at the meter panel or service
    disconnect panel.

    ®oy
     
  13. John Gilmer

    John Gilmer Guest

    Yep, that's the "no, no."
    But this happens "all the time." (Well, maybe not "all the time," but
    close. If a box is large enough there is no restriction on having more
    than one circuit pass through. But it's clear that all the GROUNDS are
    bonded together, especially if it is a metal box.
    That has potential problems in that the "ground" and "neutral" of a circuit
    may easily remain connected while both are connected from the
    "ground/neutral." IF the corresponding HOT wire remains connected, you can
    easily have a section of "ground" that's actually HOT.
     
  14. ehsjr

    ehsjr Guest

    What article?
    Ed
     
  15. John Gilmer

    John Gilmer Guest

     
  16. ehsjr

    ehsjr Guest

    Thanks!
     
  17. Phil
    I just reread your reply and I'm going to have to ask you when I
    suggested trying to "pig tail" several large conductors into a single
    connection? You say you have seen this done. What materials were used
    to do it because I cannot imagine how that could be done.
     
  18. Ben Miller

    Ben Miller Guest

    Think about what happens if those two wires are removed together. You would
    disconnect the grounded conductor and the equipment grounding conductor, but
    the circuit would still be connected to the ungrounded side of the line.
    This would be extremely dangerous if there was any leakage current or fault.

    Ben Miller
     
  19. Ben Miller

    Ben Miller Guest

    And I assume you will have an appropriate listing agency test and label
    them, so they are code compliant? Why not use the lugs that are commercially
    available, designed for the purpose, and verified by UL, as Tom Horne has
    suggested?

    Ben Miller
     
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