Electrical Power Electrical Power Distribution in Distribution in

AmericaAmerica

49.9 % Coal49.9 % Coal

20.4% Nuclear20.4% Nuclear

20.3% Natural Gas20.3% Natural Gas

6% Hydro Electric6% Hydro Electric

3.4% Other3.4% Other

http://www.eia.doe.gov/emeu/mer/pdf/pages/sec7_4.pdf

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 BrownBrown, , OrangeOrange, , YellowYellow Neutral – White Ground – Green

Voltage reading between phases (BrownBrown to to OrangeOrange, , YellowYellow to Orange to Orange, or , or YellowYellow to to BrownBrown)

480 volts

Voltage reading phase to neutral (BrownBrown to White, to White, OrangeOrange to White, or to White, or YellowYellow to to WhiteWhite)

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