Which voltages are available to ground on a 240 3-phase 3-wire system?

Which voltages are available to ground on a 240 3-phase 3-wire system?

• A. 120, 120, 240
• B. 240, 240, 0
• C. 277, 277, 277
• D. 120, 240, 120

Answer: (B)

In a 240-volt 3-phase 3-wire system, the system comprises three conductors carrying equal voltages that are 120 degrees out of phase with each other. The primary voltage between any two phases in a balanced system is 240 volts. When considering voltages available to ground in this configuration, it's important to understand that in a 3-wire system, you typically reference the measurements to the ground. With a 240-volt 3-phase alignment, the voltage from each phase to ground is indeed 240 volts. The return path of the neutral or ground is absent in a 3-wire system; thus, there’s no reference point for calculating a differing ground voltage. This can be contrasted with other configurations. For example, in a 4-wire system or when neutral is present, you would encounter other voltage levels available to ground. The indicated answer reflects that all three phases in this 3-wire system can exhibit 240 volts at ground, therefore making the answer consistent with the configuration of a 240-volt system.

In a 240-volt 3-phase 3-wire system, the system comprises three conductors carrying equal voltages that are 120 degrees out of phase with each other. The primary voltage between any two phases in a balanced system is 240 volts.

When considering voltages available to ground in this configuration, it's important to understand that in a 3-wire system, you typically reference the measurements to the ground. With a 240-volt 3-phase alignment, the voltage from each phase to ground is indeed 240 volts. The return path of the neutral or ground is absent in a 3-wire system; thus, there’s no reference point for calculating a differing ground voltage.

This can be contrasted with other configurations. For example, in a 4-wire system or when neutral is present, you would encounter other voltage levels available to ground. The indicated answer reflects that all three phases in this 3-wire system can exhibit 240 volts at ground, therefore making the answer consistent with the configuration of a 240-volt system.