A limit switch that is normally opened is open when in its default state. Which option correctly describes this?

• A. It is closed at rest
• B. It is momentary when actuated
• C. It is open at rest
• D. It is normally closed

Answer: (C)

A limit switch described as normally open means the contacts are not connected in the switch’s resting, unactuated state. In that default position the circuit is open, so no current flows. When the actuator is engaged, the contacts move to close the circuit and allow current to pass. That’s why the correct description is “open at rest.” The other statements describe different ideas: a normally closed switch would be closed at rest, a momentary action refers to how long the actuated state lasts rather than the rest state, and sometimes a switch can be maintained or momentary after actuation, but that doesn’t change the rest-state behavior described by normally open.