Electrical power supplied on three separate outputs with a phase difference of 120 degrees between any two of the outputs. Three-phase power is usually what's delivered to the service entrance of a building from the electrical utility. At the panel, the three phases are split into three single-phase legs. Large panel mount and multi-kVA UPS systems exist that function with three-phase power. Tripp Lite offers no three-phase products at this time. See single phase.