480V 3 Phase is the standard power system voltage for US industrial facilities. American National Standards Institute (ANSI) classifies 208V, 240V and 480V 3 Phase power as low voltage power systems. Other ANSI voltage classifications are Medium, High, Extra High, and Ultra High Voltage that goes up to 1,100,000V.
When you’re used to working with 120V or 240V it sounds wrong call 480V low voltage, but there it is. You don’t typically see the higher ANSI voltage classifications unless you’re in power distribution or in a very large industrial facility that requires more 4 Mega Watts.
Most US industrial facilities use 480V 3 Phase instead of 208V or 240V because it provides 2.3 (480 /208) times more or 2.0 (480 /240) times power with the same current. More important is it provides the same power with less current which provides added benefits.
- Reduced construction costs with smaller electrical service, wiring, conduits, and electrical devices.
- Reduced energy costs with less energy lost to heat in the form or current resistance.
480V 3 Phase Wye
480V 3 Phase Wye is like 208V 3 Phase Wye in that they’re both 3 Phase 4 Wire power configurations that include a neutral wire. Most 480V power systems are a Wye configuration because
- Phase to neutral voltage is 277V or below 300V
- It can power 277V single phase lighting loads
A 480 3 Phase Wye power system is called 480V 3 Phase 4 Wire and 480Y/277V. These are technically more accurate because they refer to the neutral.
- The “4 Wire” in 480V 3 Phase 4 Wire refers to the neutral as 4th wire.
- The” Y” in 480Y/277V refers to the neutral as the center of the Y shaped power source.
480V 3 Phase Delta
480V 3 Phase Delta is a 3 Wire power configuration and does not include a neutral wire. Most 480V power systems are not a Delta configuration because the phase to ground voltage is 480V or above 300V.
I’m always surprised when an industrial facility uses a 480 3 Phase Delta power system. Most of the time they are older industrial facilities so it must be related to when the facility was built.