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Thread: Shared Neutrals

  1. #1
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    Shared Neutrals

    Repeate question I'm sure.
    I'm installing 2 30a 120v circuits for a small Network closet in our office. It will be used for our 2 UPS's in the data rack.
    My question is:
    Can I run 1 #10 neutral along with my 2 #10 hots to feed the circuits or do I need 2 neutrals?
    If I read it correctly I only need 1 neutral.

    http://www.ecmweb.com/sites/ecmweb.c...5ecmCQfig2.gif

    Thanks

  2. #2
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    Call a licenced electrician.....

  3. #3
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    Quote Originally Posted by cdslotz View Post
    Call a licenced electrician.....
    Apprentices are allowed to ask questions.
    "Electricity is really just organized lightning." George Carlin


    Derek

  4. #4
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    Quote Originally Posted by Fly-Guy5 View Post
    Repeate question I'm sure.
    I'm installing 2 30a 120v circuits for a small Network closet in our office. It will be used for our 2 UPS's in the data rack.
    My question is:
    Can I run 1 #10 neutral along with my 2 #10 hots to feed the circuits or do I need 2 neutrals?
    If I read it correctly I only need 1 neutral.

    http://www.ecmweb.com/sites/ecmweb.c...5ecmCQfig2.gif

    Thanks
    Yes, as long as you put it on a 2 pole breaker or use a tie bar on 2 single pole breakers. and they are on opposite phases.
    But, You need to read installation manual first. MFGR. may require a private neutral for each UPS.
    Sometimes I don't know whether I'm the boxer or the bag.

  5. #5
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    Phoenix, AZ USA
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    Quote Originally Posted by Fly-Guy5 View Post
    Repeate question I'm sure.
    I'm installing 2 30a 120v circuits for a small Network closet in our office. It will be used for our 2 UPS's in the data rack.
    My question is:
    Can I run 1 #10 neutral along with my 2 #10 hots to feed the circuits or do I need 2 neutrals?
    If I read it correctly I only need 1 neutral.

    http://www.ecmweb.com/sites/ecmweb.c...5ecmCQfig2.gif

    Thanks
    By NEC you can share neutrals as long as you use handle ties to "interlock" the two breakers. So the circuits need to be next to each other in the panel. If this is not possible, then you need separate neutrals.
    The reason for this "as I see it, as a former service technician", If you are working on a circuit, you should have it turned off (in general for safety), If you have that circuit off, and the circuit that shares it's neutral is NOT turned off (hence the handle tie) then you can get zapped on the neutral when you take it apart, because it is still serving the other circuit.
    As an estimator let me request that you ALWAYS ADD DEDICATED NEUTRALS, fatten up those estimates boys!

  6. #6
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    As pointed out, the NEC allows sharing of neutrals, but the NEC is not a design manual.

    Some would be concerned about triplen harmonics and ask for dedicated neutrals.
    Ron

  7. #7
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    You have to become a member to ask a question.....and anyone can become a member...right?

  8. #8
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    Quote Originally Posted by cdslotz View Post
    You have to become a member to ask a question.....and anyone can become a member...right?
    Anyone who is in the electrical field may participate in this forum.
    "Electricity is really just organized lightning." George Carlin


    Derek

  9. #9
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    Can you account for the possibility of triplen harmonics with a larger, but still shared, neutral? I know I've seen it, but don't know if that was work done to Code at the time.

  10. #10
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    Quote Originally Posted by MAC702 View Post
    Can you account for the possibility of triplen harmonics with a larger, but still shared, neutral? I know I've seen it, but don't know if that was work done to Code at the time.
    Yes, some vendors call that a Super Neutral.

    http://www.afcweb.com/mc-metal-clad-...sized-neutral/
    Ron

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