NO/ NC

[kwired]

Fairly simple example.

Switch actuated by refrigerator door to turn on interior light when the door is opened.

Switch is normally closed when in an uninstalled and unused "off the shelf" state.

But when in use is usually "held open" any time the door is shut, which may very well be considered it's normal state while in use even though it is technically a normally closed switch.

 

[ActionDave]

Fairly simple example.

Switch actuated by refrigerator door to turn on interior light when the door is opened.

Switch is normally closed when in an uninstalled and unused "off the shelf" state.

But when in use is usually "held open" any time the door is shut, which may very well be considered it's normal state while in use even though it is technically a normally closed switch.

Still call it normally closed.

 

[kwired]

Still call it normally closed.

Correct, but in this application it is normally closed held open.

 

[Besoeker]

contacts are shown in the de-energized state (shelf state)

Yep. It is no more complicated than that.

 

[zbang]

Yep. It is no more complicated than that.

Well.... All this applies to a switch or contacts that will return to a certain state when an external stimulus is removed. Your bog-standard toggle switch will not, and IMHO then doesn't have a "normal" state until you define something that ties the contact position to the external state: "down is normal", "off position is normal", "stop button pulled out is normal". Some of these are assumed but some won't be.

(Way back when I did alarm systems, in the computers we used the terms Active and Restored to refer to the binary states of an input, didn't care about the contacts at that point.)