Which device is used to detect human presence in the guarded space?

• A. Safety fences
• B. Floor markings
• C. Light curtains
• D. Tooling

Answer: (C)

Detecting presence in a guarded space relies on a device that actively monitors entry and can trigger an immediate shutdown for safety. Light curtains achieve this by creating a grid of infrared beams across an access point. When any beam is interrupted by a person, the safety system detects the intrusion and stops the machine, keeping the worker safe inside the guarded area. This combination of real-time detection and rapid response is essential for protecting people in hazardous zones.

Safety fences are physical barriers that prevent entry but don’t provide automatic detection once someone is inside; floor markings are just visual guides and don’t trigger any protective action; tooling refers to equipment used to process or hold parts and does not function as a presence-detection device.