Single Phase vs. Three Phase Power

Power is commonly distributed in one of two ways - single phase or three phase power systems.  What is the difference?

At high level, single phase systems distribute power using AC (alternating current) across typically a 2-wire system (one wire carrying power, one wire being neutral).  

In contrast, three phase systems distribute power also using AC, but in 3 phases that are 120 degrees out of phase with one another (typically across 4-wires - 3 power wires and one neutral wire)

In practical terms, typically single phase power is used in household applications where as three phase power is commonly used in industrial / commercial applications (also seen more and more in data center applications).

Three phase power allows for the level of power to remain consistent due to the overlapping phases and typically requires less wiring / conductive material than an equivalent single phase system.


Samsara PM20s can be used to monitor three-phase power or single-phase power. Samsara PM10s can monitor single-phase power and are designed to provide breaker-level visibility in sub-junction boxes.

Used together, PM20s and PM10s provide end-to-end insight into three-phase and single-phase energy usage across an enterprise campus. 

See the PM-family Installation Guide for more details: