Commercial Refrigeration II Practice Exam 2026 - Free Refrigeration Exam Practice Questions and Study Guide

A potential relay is a voltage-sensing device where the default condition is the coil being de-energized. In that unenergized state the contacts are closed, meaning the circuit is complete. When the sensed voltage reaches its set threshold and energizes the coil, the magnetic action pulls the contact open, interrupting the circuit. So, the default state of the contacts is normally closed. The idea of “open only during actuation” describes what happens when the coil is energized, not the default state, and “shorted when energized” isn’t how relay contacts operate.