When a 120/208-volt, 3Ø, 4-W supply system delivers power to a load, what does the line voltage equal?

The line voltage in a 120/208-volt, 3-phase (3Ø), 4-wire system specifically refers to the voltage measured between any two line conductors. In this system, the phase voltage (the voltage measured from any one phase to neutral) is 120 volts. However, the line voltage, which is the voltage across two phases, is 208 volts.

To derive this, you can use the relationship between line voltage (V_L) and phase voltage (V_Ph) for a 3-phase system:

V_L = √3 × V_Ph

Substituting the known phase voltage into the equation:

V_L = √3 × 120 volts ≈ 208 volts

Thus, the line voltage accurately equals 208 volts when the supply system delivers power to the load. This understanding is critical when working with 3-phase systems in electrical design and installation.