What are the line-to-line voltages in a 3Ø, 4-W supply system delivering 120/208 volts?

In a three-phase (3Ø) electrical system, the line-to-line voltages can be determined based on the configuration of the supply. In a 3Ø, 4-wire system that delivers a voltage specification of 120/208 volts, the voltage of 120 volts refers to the line-to-neutral voltage, while the 208 volts represents the line-to-line voltage.

The reason the line-to-line voltage is correctly identified as 208 volts is due to the relationship between line-to-neutral voltage and line-to-line voltage in a three-phase system. The formula to convert the line-to-neutral voltage (which is 120 volts in this case) to line-to-line voltage is to multiply the line-to-neutral voltage by the square root of 3 (approximately 1.732). Thus, when you calculate 120 volts × √3, you arrive at about 208 volts.

This understanding is crucial for any electrical technician as it highlights the fundamental principles behind three-phase systems and helps ensure proper voltage configuration in installations and maintenance.