What is a common usage of AND logic?

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

Answer: (B)

AND logic means the output only activates when every required input is active. In industrial safety and control, this is used to ensure that a dangerous action can begin only when both conditions are met. A two-hand start circuit is the classic application: both pushbuttons must be pressed at the same time to start the machine. This guarantees that the operator’s hands are away from the hazardous area when the machine begins, which is exactly what AND logic is designed to enforce. If either button is released, the start command isn’t produced, so the machine won’t start.

The other options don’t fit this pattern. An emergency stop pushbutton provides a direct shutoff and is typically used as a single input that stops the machine, not as a requirement for starting. A remote-start pushbutton allows starting from a distance, which doesn’t require both hands. Multiple stop pushbuttons are about stopping from any location (often arranged so that pressing any one stops the machine), which aligns with OR-type behavior rather than AND.