How can you identify normally open vs normally closed contacts in a schematic?

• A. NC contacts open when energized; NO contacts close when energized.
• B. NO contacts close when energized; NC contacts open when energized.
• C. NO contacts stay open at all times; NC contacts stay closed at all times.
• D. The symbols indicate mechanical vs electronic contact.

Answer: (B)

Normally open versus normally closed contacts are defined by how they behave when the controlling device is not energized and when it is energized. A normally open contact is open in the resting, unenergized state and will close when the coil or actuator is energized. A normally closed contact is closed in the resting state and will open when energized. The answer aligns with this behavior, stating that NO contacts close when energized and NC contacts open when energized. In schematics you can often spot them by the symbol: NO shows as a contact with a gap that closes when actuated, while NC appears as a contact that is closed at rest and opens when energized. If you test with a continuity meter, NO will show continuity only when energized, whereas NC will show continuity at rest and lose it when energized.