Automation
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110-BTQ-01-IGOT © 2024, Workplace Safety & Prevention Services (WSPS)
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Interlocks on Access Points
Interlocks are safety devices that interrupt and prevent machinery from operating when access
points, such as doors or guards, are open. They ensure the machine stops functioning before a
worker can reach any hazardous parts. Various interlocks, including mechanical, electrical, and
electronic, are each suited to different applications.
When implementing interlocks, it's vital to ensure that the time it takes to access the machine's
hazardous areas is longer than the time it takes for the machine to stop. Regular maintenance and
testing of interlocks are crucial to ensure they work correctly and provide the necessary protection.
It is also important to remember that machinery/automation equipped with interlocking or other
protective devices that signal a stop must have a Pre-Start Health and Safety Review completed by
an Ontario licensed Professional Engineer following Industrial Establishments – O. Reg. 851, section 7.
Implement corrective measures cited for compliance before operating or using the equipment.
Review these articles for more information:
Operating Machines Safely: 4 Obstacles and Tips to Overcome Them
Machine Guarding and Electrical Hazards
Warning Lights to Indicate Cycling of Equipment
Warning lights indicate when equipment is operating or cycling, alerting workers to avoid
hazardous areas.
Use standard color codes* to ensure clear communication and quick recognition.
Install warning lights in visible locations on or near the equipment to ensure all workers can
easily see them.
Regularly check and maintain warning lights to ensure they function correctly and replace
any faulty lights promptly.
Integrate warning lights with the equipment's control system to automatically activate during
operation cycles.
* Green typically indicates a normal operating condition.
Yellow is generally a warning signal, that indicates an abnormal condition that requires attention.
Red indicates a critical or emergency condition, that requires immediate attention (e.g. fault, shutdown, etc.)
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