What is a common usage of NOR logic?

• A. Emergency stop pushbuttons
• B. Remote-start pushbutton
• C. Multiple stop pushbuttons
• D. A two-hand start circuit

Answer: (C)

NOR logic outputs a true signal only when every input is false. When you have several stop devices around a machine, you want the machine to run only if none of them are actuated. Wiring the stop pushbuttons in a NOR configuration means the run circuit stays enabled as long as no stop button is pressed (all inputs are false). If any stop button is pressed, at least one input becomes true, the NOR output goes false, and the machine stops immediately. This provides a simple, reliable way to implement a multi-point stop system. Other options describe different functions (emergency stop, remote start, two-hand start) that don’t reflect the all-clear condition NOR logic is best suited for.