Electrical Power Distribution in America

49.9 % Coal 20.4% Nuclear 20.3% Natural Gas 6% Hydro Electric 3.4% Other

Power Plant Generation  Turbines Output 11KV to 22KV

Generated Power Distribution  Power Plant Turbine Output Voltage Transformed to Higher Voltage 155,000 volts to 765,000 Volts Higher voltage, lower current = less line loss

End User  High Distribution Voltage Transformed Down  Common Commercial Substation Voltage 12,000 Volts  Residential 7,200 Volts

Commercial End User  Transformed From 12,000 Volts, 3 Phase 480/277 Volts Three Phase 208/120 Volts Three Phase

480/277 Volt Rules of Thumb  Phase Conductors Marked Brown, Orange, Yellow Brown, Orange, Yellow Neutral – White Ground – Green Brown to Orange, Yellow to Orange, or Yellow to Brown  Voltage reading between phases (Brown to Orange, Yellow to Orange, or Yellow to Brown) 480 volts Brown to White, Orange to White, or Yellow to White  Voltage reading phase to neutral (Brown to White, Orange to White, or Yellow to White) 277 volts

208/120 Volt Rules of Thumb  Phase Conductors Marked Black, Red, Blue White - Neutral Green – Ground  Voltage Reading Between Phases (Black to Red, or Red to Blue or Black to Blue) 208 Volts  Voltage Reading Phase to Neutral (Black to White, Red to White, Blue to White) 120 Volts

Residential End User  Transformed From 7,200 Volts 240/120 Volts Single Phase

Residential Single Phase  3 Wire’s coming into your home Black and Red Wires are Hot 1 White is Neutral  Voltage between the two hot wires (Black to Red) 240 volts  Voltage between hot and neutral (Either the Black to White or the Red to White) 120 volts