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Thread: shared neutral

  1. #1
    Join Date
    Jun 2010
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    19

    shared neutral

    Hi ,
    i have some em fixtures with built in batteries, the engineer screwed up and sourced the feed from a motorized breaker panel so there is no constant hot available to feed the em battery ballast,
    His solution is to bring a hot wire only from another panel and use the 1 neutral from the motorized breaker panel for both circuits and ballasts.
    seems wrong to me but i cant find any code issue..

    is there a code issue with this install ???????

  2. #2
    Join Date
    Sep 2016
    Location
    Longmont, CO
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    Absolutely!

    300.3 Conductors.


    (B) Conductors of the Same Circuit. All conductors of the
    same circuit and, where used, the grounded conductor and all
    equipment grounding conductors and bonding conductors shall
    be contained within the same raceway, auxiliary gutter, cable
    tray, cablebus assembly, trench, cable, or cord, unless otherwise
    permitted in accordance with 300.3(B)(1)through (B)(4).

  3. #3
    Join Date
    Feb 2009
    Location
    Durango, CO, 10 h 20 min without traffic from winged horses.
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    Quote Originally Posted by dj94 View Post
    His solution is to bring a hot wire only from another panel and use the 1 neutral from the motorized breaker panel for both circuits and ballasts.
    seems wrong to me but i cant find any code issue..

    is there a code issue with this install ???????
    Yes, it is a code issue and it is a huge safety issue.

    Think about it. You go to the panel and turn off the breaker go back to whatever you are working on and test for power and verify that the power is indeed off so you start breaking connections and now one of those neutral wires that was at zero volts to ground is now 120V or 277V above ground because it's being fed from a different breaker, in a different panel that you didn't know about, and you get the nastiest shock of your life on something that you correctly killed the power to and correctly verified the power was off.

    Tell the EE he needs to learn some more about electrical circuitry before he makes another suggestion that might get somebody hurt.
    Once in a while you get shown the light
    In the strangest of places if you look at it right. Robert Hunter

  4. #4
    Join Date
    Jun 2010
    Posts
    19
    Quote Originally Posted by Jim1959 View Post
    Absolutely!

    300.3 Conductors.


    (B) Conductors of the Same Circuit. All conductors of the
    same circuit and, where used, the grounded conductor and all
    equipment grounding conductors and bonding conductors shall
    be contained within the same raceway, auxiliary gutter, cable
    tray, cablebus assembly, trench, cable, or cord, unless otherwise
    permitted in accordance with 300.3(B)(1)through (B)(4).
    hi Jim ,
    i see the code reference but if i carry a neutral and don't use it at the other end that covers the requirement.
    still not telling me i cant land the hot only without some interpretation correct?

  5. #5
    Join Date
    Jun 2010
    Posts
    19
    Quote Originally Posted by ActionDave View Post
    Yes, it is a code issue and it is a huge safety issue.

    Think about it. You go to the panel and turn off the breaker go back to whatever you are working on and test for power and verify that the power is indeed off so you start breaking connections and now one of those neutral wires that was at zero volts to ground is now 120V or 277V above ground because it's being fed from a different breaker, in a different panel that you didn't know about, and you get the nastiest shock of your life on something that you correctly killed the power to and correctly verified the power was off.

    Tell the EE he needs to learn some more about electrical circuitry before he makes another suggestion that might get somebody hurt.
    Hi Dave ,
    I see your point fully but the EE wont back off of this without a direct code violation, for instance if each fixture is marked

    "Danger 2 sources of power BP1-37 and RP-37"

    wouldn't that "cover" the safety issue with the due diligence we put in by labeling the lights ??

  6. #6
    Join Date
    Feb 2009
    Location
    Durango, CO, 10 h 20 min without traffic from winged horses.
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    Quote Originally Posted by dj94 View Post
    hi Jim ,
    i see the code reference but if i carry a neutral and don't use it at the other end that covers the requirement.
    still not telling me i cant land the hot only without some interpretation correct?
    If you have a wire in a pipe that you are not using then it's not a circuit conductor it's just a spare white wire plus if it is metal conduit you need to meet 300.20.
    Once in a while you get shown the light
    In the strangest of places if you look at it right. Robert Hunter

  7. #7
    Join Date
    Sep 2016
    Location
    Longmont, CO
    Posts
    105
    Quote Originally Posted by dj94 View Post
    hi Jim ,
    i see the code reference but if i carry a neutral and don't use it at the other end that covers the requirement.
    still not telling me i cant land the hot only without some interpretation correct?
    the hot and neutral (or whatever current carrying conductors of a circuit) must be run together. When they are in close proximity, they cancel eachother's magnetic fields. If this is not done, it can cause heating, radio interference at the least; especially in metallic conduit. sorry for the late reply, I was out on Friday.

  8. #8
    Join Date
    Jun 2006
    Location
    Ohio
    Posts
    20,259
    Quote Originally Posted by dj94 View Post
    hi Jim ,
    i see the code reference but if i carry a neutral and don't use it at the other end that covers the requirement.
    still not telling me i cant land the hot only without some interpretation correct?
    Quote Originally Posted by dj94 View Post
    Hi Dave ,
    I see your point fully but the EE wont back off of this without a direct code violation, for instance if each fixture is marked

    "Danger 2 sources of power BP1-37 and RP-37"

    wouldn't that "cover" the safety issue with the due diligence we put in by labeling the lights ??
    Perhaps this will help...

    210.4 Multiwire Branch Circuits.

    (A) General.
    Branch circuits recognized by this article shall
    be permitted as multiwire circuits. A multiwire circuit shall be
    permitted to be considered as multiple circuits. All conductors
    of a multiwire branch circuit shall originate from the same
    panelboard or similar distribution equipment.



    Informational Note No. 1: A 3-phase, 4-wire, wye-connected
    power system used to supply power to nonlinear
    loads may necessitate that the power system design allow
    for the possibility of high harmonic currents on the neutral
    conductor.

    Informational Note No. 2: See 300.13(B) for continuity of
    grounded conductors on multiwire circuits.

    (B) Disconnecting Means. Each multiwire branch circuit
    shall be provided with a means that will simultaneously
    disconnect all ungrounded conductors at the point where
    the branch circuit originates.



    Informational Note: See 240.15(B) for information on the
    use of single-pole circuit breakers as the disconnecting means.

    (C) Line-to-Neutral Loads. Multiwire branch circuits
    shall supply only line-to-neutral loads.

    Exception No. 1: A multiwire branch circuit that supplies
    only one utilization equipment.

    Exception No. 2: Where all ungrounded conductors of the

    multiwire branch circuit are opened simultaneously by the
    branch-circuit overcurrent device.

    (D) Grouping. The ungrounded and grounded circuit conductors
    of each multiwire branch circuit shall be grouped
    by cable ties or similar means in at least one location within
    the panelboard
    orother point of origination.

    Exception: The requirement for grouping shall not apply if
    the circuit enters from a cable or raceway unique to the
    circuit that makes the grouping obvious or if the conductors
    are identified at their terminations with numbered wire
    markers corresponding to the appropriate circuit number.
    90.1 Purpose.

    (A) Practical Safeguarding.
    The purpose of this Code is
    the practical safeguarding of persons and property from
    hazards arising from the use of electricity. This Code is not
    intended as a design specification or an instruction manual
    for untrained persons.

    ...
    I'll never get there. No matter where I go, I'm always here.

  9. #9
    Join Date
    Dec 2010
    Posts
    1,113
    Where did MWBC sneak in?
    The more they overthink the plumbing, the easier it is to stop up the drain

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