Forums » Electrical Engineering

3 ph without one leg.

    • 7 posts
    March 1, 2019 1:40 PM PST

    A distribution to the panel board which feeding a 3 ph load, is done with only two phases a and b but c is missing. Is  this  a violation of code???

    • 148 posts
    March 1, 2019 1:47 PM PST

    This comes up a lot on other forums and the consensus is that it is not a violation.  Obviously you will only have 2 phases active unless you jump to phase C from one of the others.  In either case there is nothing in the NEC that suggest this is a violation unless you might want to use 110.3(B).  I don't believe the instructions state that all 3 phases must be used.  

     

    (B) Installation and Use. Listed or labeled equipment shall be
    installed and used in accordance with any instructions included
    in the listing or labeling.

    • 37 posts
    March 1, 2019 1:55 PM PST

    This panel board will be dedicated only for 1 phase consumer but not 3 ph consumer?

  • March 1, 2019 2:38 PM PST
    Rechart Grand said:

    A distribution to the panel board which feeding a 3 ph load, is done with only two phases a and b but c is missing. Is  this  a violation of code???

    I need some more context.  It feels like we are only getting only half the story.  Or I'm not clear on what you are saying.

    My translation is:

    You have a panelboard feeding 3-phase loads, which, of course means the panelboard has to be 3-phase.  However, the feed to the panelboard is only two legs of the three phases

    If this is so, I wouldn't worry about the code.  The load is not going to work.  And that is going to irritate the owner.  And nobody wants an irritated owner with a cricket bat chasing one down.

    So, I'm thinking, I am not clear on what you are saying.

    carl