In the USA the two commonly supplied shore-power voltages are 120 Volts (60Hz) AC and 240 Volts (60Hz) AC. The standard in Europe is 230 Volts (50Hz) AC. All of these supplies are single phase, but there are differences in the supply wire configurations and consequently in the power distribution panel structure. The chart below illustrates the differences.
| USA, 120 Volt-60Hz | USA, 240 Volt-60Hz | EUROPE, 230 Volt-50Hz |
|---|---|---|
| HOT NEUTRAL SAFETY GROUND | HOT HOT NEUTRAL SAFETY GROUND | HOT NEUTRAL SAFETY GROUND |
| The USA 120 V (60Hz) supply typically has three wires, 1-hot, 1 neutral, and 1-safety ground. 120V (60Hz) is obtained between the hot and neutral leads. | The USA 240V (60Hz) supply typically has 4 wires, 2-hot, 1-neutral, and 1-safety ground. 120V (60Hz) is obtained between either hot lead an neutral, with 240V (60Hz) obtained between the 2 hot leads. | The EUROPEAN 230V (50Hz) supply consists of 3 wires like the US. 1-hot, 1-neutral, and 1-safety ground. 230V (50Hz) is obtained between the hot and neutral lead. |
| Double-pole main circuit breaker protects both the hot and the neutral leads. *See note below | Main breaker protects both hot leads. Triple-pole breaker may be used to also protect neutral. | Double-pole main circuit breaker protects both the hot and the neutral leads. *See note below |
| Branch circuit breakers are single-pole, switching the hot lead. | Branch breakers for 240V circuits are double-pole switching both the hot leads. Branch breakers for 120V circuits are single-pole, breaking just the hot lead. | Branch circuit breakers are single-pole, switching the hot lead. |
| Has hot bus connected to the line side of the branch breakers. Has separate buses for neutral and safety ground. | Has 2 separate hot buses connected to branch breakers. Has separate buses for neutral and safety ground. | Has hot bus connected to the line side of the branch breakers. Has separate buses for neutral and safety ground. |
*Note:
Standard European practice and ABYC requirements include ground-fault protection for the entire AC system as well as critical branch circuit GFCI protection.
Please reference: Technical Brief "AC Ground Faults, the Boater, and ABYC—Understanding Equipment Leakage Circuit Interrupters (ELCIs) and Ground Fault Circuit Interrupters (GFCIs) to make your boat safer." for more information.
