Three-phase power is a 3-wire Alternating Current (A/C) power circuit. Most US commercial buildings use a three-phase 4-wire 208Y/120V power arrangement because of its power density and flexibility. Compared to the more common single-phase, a three-phase power arrangement provides 1.732 (the square root of 3) times more power with the same current and provides seven (7) power circuits.
At present, a Sense Home monitor system can only monitor two of the three phases in three-phase panel setups. The most obvious limitation right now is that our hardware only includes two sensors to monitor current and so two wires to monitor voltage. This limitation does not exist if your Sense system is in a Sense-enabled meter.
While the hardware workaround is to monitor two of the three phases, it is important to realize that this is not an ideal scenario. There will be one phase that is left entirely unmonitored by Sense, and the homeowner must be OK with this.
A scenario where this works best is if the installation is in a condo or apartment unit. Typically, the main panel for the entire building is three-phase; however, each apartment or condo unit’s subpanel is receiving power from only two of the three phases. In this case, the setup would look the same as a common home's split-phase panel setup.
NOTE: If you are a Sense partner, you should make a note of this setup on the Phase type page of the Sense Pro app.