Download 208V vs 120V FAQ

208V vs 120V FAQ
Can my server use 208V?
Most 2005 and later power supplies for electronic equipment use auto-sensing 100-250V input
voltages. Some earlier models used "switchable" 120-240V p.s.s.
What makes using 208V better than 120V?
The main reason that 208V is better is 120V has wasted heat. The higher the voltage used, the
lower the amps used, lowering the wasted heat in several ways:
1. Even though amps is a measure of the volume of electric energy, a given watt-load would incur
less resistance through the same cord size when less amps are required.
For a 250W server:
@ 120V, the amps draw is (from: Watts=Volts* Amps) = 2.08 Amps
@ 208V, the amps draw is = 1.20 Amps
Even over small copper wires, the heat in the cord is reduced when using 208V.
2. A/C electrical energy using two wires (a circuit) at 120V uses one "hot" wire and one "neutral"
circuit return wire, which is normally grounded. The neutral wire bleeds a small (5%) loss to the
ground when compared with the same wattage loads in a normal colocation electrical setup.
A 3phase 2-wire 208V (3 circuits: A+B, B+C, & C+A) uses less energy in comparison to a singlephase 120V (3 circuits: A+N, B+N, & C+N) burning the same wattage. The neutral wire is used
conventionally for low voltage circuits; it was developed in the USA in the early 1900's as a safer
circuit, with one wire grounded. A 208-volt circuit is more efficient.