Interlock Guard
An interlock guard (or interlocked guard) is a movable physical barrier monitored by a machine's control system, preventing hazardous motion from starting or automatically stopping it when the guard is not closed. It ensures workers cannot access hazardous areas while machinery operates, as defined by WorkSafeBC, CSA Z432:23, and CCOHS, requiring compliance with safety standards for effective protection.
On the shop floor, interlock guards are used where workers need routine access to hazardous areas, such as loading, unloading, or clearing jams, on machines like tumbler drums, conveyors, robotic cells, and presses. They function by allowing hazardous motion only when the guard is closed, requiring a separate start control, and stopping motion immediately if the guard is opened. For SafeDesk compliance with WorkSafeBC, machines with movable guards must be inventoried and classified as requiring interlocked guards, referencing BC OHSR Part 12 and CSA Z432:23. Interlock guards are operational safeguards, not substitutes for lockout during maintenance, which requires de-energization under Part 10.
What is the difference between a guard and an interlock guard under WorkSafeBC?
A guard is a physical barrier preventing access to moving parts, while an interlock guard is that barrier attached to and monitored by the control system, ensuring hazardous functions cannot operate unless the guard is closed and stop if opened, providing functional safety behavior beyond physical separation.
Which standards govern the design of interlock guards in BC/Canada?
BC OHSR Part 12 and the BC Safeguarding of Machinery Guidance require compliance with CSA Z432:23 Chapter 9.5 for interlocked guards. ISO 14119 provides detailed categories of interlocking devices, and ANSI B11.19 is referenced in U.S. contexts for performance requirements.
How do interlocked guards interact with lockout/tagout under WorkSafeBC?
Interlocked guards are operational safeguards for normal operation, but for maintenance or servicing, OHSR Part 10 requires de-energization and lockout using energy isolating devices or control system isolating devices. Interlocks alone do not satisfy lockout requirements and must never be treated as lockout devices.