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What? How come?

Working on a regular AC system (RTU , new to me)  my cohort said "we have 216v ,L1 to L2 .BUT, BUT we have 123v to ground L 1 &  123 V to ground L2! What What? How How come???


  • SWEI
    SWEI Member Posts: 7,356
    3ø Wye System

    With a tad of imbalance (should be 213V L-L if all is well.)
  • Kakashi
    Kakashi Member Posts: 88
    electrician time

    How is it wired in breaker box? Do you have 220 there?
  • Techman
    Techman Member Posts: 2,144

    Our measurements were at the AC unit disconnect. Do not know what is at the CB panel.
  • SWEI
    SWEI Member Posts: 7,356
    I thought you were posting another quiz

    In a three phase wye system, line to line voltage is equal to the √3 times the line to neutral voltage.

    123V line to neutral times 1.732 = 213 V line to line.

    Slight variations can be caused by nonlinear loading or the use of a DVM which does not measure true RMS AC.
  • Techman
    Techman Member Posts: 2,144

    Truth be told , I'm asking for a fellow wallie ! He didn't want to ask! Shame on him!!!!Your welome!

    SWEI- Thanks! I know about that stuff ,but I don't know about that stuff . Know what I mean?