How do normally open and normally closed contacts differ in state when the control coil is de-energized?

• A. NO is closed and NC is open when the control coil is de-energized.
• B. NO is open and NC is closed when the control coil is de-energized.
• C. Both NO and NC are open.
• D. Both NO and NC are closed.

Answer: (B)

In a relay or contactor, contacts are categorized as normally open and normally closed, and their behavior is described in the de-energized (rest) state. When the control coil is not energized, a normally open contact sits open, meaning no current can pass through it. A normally closed contact, on the other hand, stays closed, allowing current to flow.

So, with the coil de-energized, the normally open contact is open and the normally closed contact is closed. This is why the correct description is that NO is open and NC is closed when the control coil is de-energized. If the coil were energized, the normally open contact would close and the normally closed contact would open.