PUWER unexpected startup of machinery

This Article is a sub-topic of the PUWER Guide
Apr 05, 2023

PUWER Inspection Learning

Measures to prevent unexpected start up during routine tasks in hazard zones protected by interlocked movable guard or protective devices.

Where access to the hazard zone is required during normal operation, and the cumulative frequency of tasks is weekly or greater the machine designer may choose to use an interlocked movable guard or protective devices (to initiate an appropriate control response to achieve a safe condition for dangerous moving parts).

Typical Control Measures

When interlocked movable guards are used to prevent access to the hazard zone during normal operation they shall be designed and positioned such that during normal operation they are prevented from closing with persons in the hazard zone. For example; when the interlocked movable guard is open, and the operator is undertaking their routine task, it is not physically possible to close the interlocked movable guard – as the operator obstructs it, or the gap between the interlocked movable guard (or protection device) and machine should normally be sufficiently small to prevent anybody remaining in it without being detected – from the control position (where the machine is started from). Note, the interlocked movable guard shall be designed to mitigate the risk of closing under the effect of gravity.

Useful References

L22; reg 11, Machinery Directive/Supply Regulations EHSR 1.2.2,

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