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120V or 240V Three-Phase Delta

Three-phase delta installation measuring power coming from a power utility (grid). The color diagram below shows a 208V delta, but this also applies to a 120V delta or 240V delta.




  •  CAUTION: Since there is no neutral and none of the phases may be grounded, all conductive/metallic parts, including CT-plug screws and CT wiring should be considered live and hazardous!
  •  If one of the phases is grounded, wire that phase to the Neutral (N) pin on the eGauge.
  • The eGauge inputs can measure up to 277V L-N terminal. A 600V delta must be measured the same way as a 480V Delta.

  • The eGauge is a Blondel Compliant meter and will measure accurately the total load of a three-wire three-phase service using two CTs when correctly installed as outlined in this document. 

    This method of eGauge installation employs the Two-Wattmeter Method of power measurement which is based on Blondel's Theorem. Blondel's Theorem essentially states that you need one less CT than the number of current carrying conductors in your service to accurately meter the total load of the service. Further research on these topics, if needed is left to the reader.

    When completing an installation of this type it's particularly important to adhere to the wiring diagram included in this document.  CT orientation must be consistent and phase verification should always be performed to ensure that there is no phase mismatch between CTs and their respective Line voltages.