What type of contacts are always associated with stop pushbuttons?

Stop pushbuttons are typically associated with normally closed contacts. This design ensures that when the stop pushbutton is in its resting state (not pressed), the circuit remains closed and allows current to flow. The moment the stop button is pressed, it opens the contacts and interrupts the flow of current, hence stopping the machine or process.

Using normally closed contacts for stop functions provides a fail-safe mechanism. If a wire were to break or a component failed, the normally closed contacts would ensure that the machine does not continue operating unexpectedly, thus providing a safety advantage in industrial settings.

In contrast, normally open contacts would only complete the circuit when activated, which would be inappropriate for functions requiring immediate interruption. Momentary contacts, whether open or closed, are designed for temporary action, which would not provide the necessary reliability and safety for a stop function where immediate disengagement is critical.