Power factor and three-phaseQuestion 1016 of 1506

A balanced three-phase four-wire Y system has equal resistive loads on all phases. Why is the neutral wire still installed?

To carry most of the main load current
To raise the line voltage up to 240 V
To change the phase sequence of the supply
To keep load voltages steady if a load opens

Show answer

Correct answer: To keep load voltages steady if a load opens

With balanced loads it carries almost no current, but it keeps the phase voltages stable after a failure.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 7.2: Three-phase Power Systems

Questions last reviewed: 18 October 2026

Red Seal Electrician Practice needs JavaScript to run. Use its questions for practice. The real pass mark is usually 70%. Check it with your province or territory's apprenticeship office.