What ground voltages are available on a 120/240 3-phase 4-wire system?

In a 120/240 volt three-phase four-wire system, the common voltages available are associated with how the system is configured and the relationship between phase and neutral points.

The correct answer reflects the typical voltage output, where two of the phases provide 120 volts each relative to the neutral, and the voltage between the phases typically is 208 volts in a three-phase configuration when calculated through the line-to-line voltage in a wye connection configuration. This voltage arises from the equation for three-phase systems, where the line-to-line voltage is √3 times the phase voltage.

Thus, in sum, we have two phases at 120 volts to neutral and the line-to-line voltage as 208 volts, which accurately represents the potential voltage measurements that can be encountered in a 120/240 three-phase system. The inclusion of 120, 120, and 208 provides a comprehensive view of the differing voltages present across the system's phases.