The Raritan Blog

Data Center: Know the Difference Between Three-Phase & Single-Phase Power

Rick Gonedes
August 3, 2017

Throughout North America, homes are powered by 120-volt single-phase electricity. A typical residential circuit breaker box reveals four wires coming into our homes: two “hot” wires, a neutral wire and ground. The two "hot" wires carry 240 VAC, which is used for heavy appliances like electric ranges and dryers. However, the voltage between both hot wire and the neutral wire is 120 VAC, which powers everything else in our homes. However, electricity generating manufacturing plants in North America transmit three-phase power at super high voltages ranging between 230 kV and 500 kV. A close look at high tension power lines reveals three separate conductors, each of which carries current, plus a neutral conductor. Three-phase power is less costly to distribute because transmission lines for three-phase power don't need the same heavy gauge copper wires as a single-phase transmission line would need. Further, three-phase offers flexibility at the service connection and can give customers not only the customary 120 VAC service but also 208 VAC. Virtually every industrial building, including yours, receives three-phase power, as it offers many advantages over single-phase.

Designing or retrofitting a data center to use three-phase power pays off, but some centers do not understand the benefits three- phase power brings. Let's take a look at the differences between single and three-phase power to understand why three-phase power not only delivers real cost savings but creates a more efficient data center.