Why would a machine use a limit switch for a safety interlock?

• A. To ensure the machine guard is in place before operation
• B. To regulate speed
• C. To monitor temperature
• D. To indicate fault

Answer: (A)

Using a limit switch as a safety interlock focuses on ensuring the protective guard is in place before the machine can operate. The switch is arranged so it is actuated only when the guard is closed. When closed, the switch completes the control circuit and allows the machine to start; if the guard is opened, the circuit is broken and operation is prevented or halted. This directly links guard position to machine safety, stopping access to moving parts and reducing injury risk. Other functions like regulating speed, monitoring temperature, or indicating faults don’t verify guard placement and therefore aren’t fulfilling the same safety role.