Keep people away from the moving parts — and keep the guards working
Unguarded machinery causes some of the worst workplace injuries — entanglement, crushing and amputation from moving parts and nip points. The answer is to safeguard the danger zone, and in New Zealand the benchmark is the AS/NZS 4024 Safety of Machinery series. Fixed guards, interlocked guards and presence-sensing devices each have a place, but they only protect people if they are designed properly, never overridden, and backed by good isolation for servicing.
WorkSafe expects duty holders to use the AS/NZS 4024 Safety of Machinery series as the current state of knowledge for safeguarding machinery and plant. It is the primary standard to benchmark against — covering risk assessment and reduction (4024.1201), the design of guards (4024.1601), interlocking devices (4024.1602), prevention of unexpected start-up (4024.1603), emergency stops (4024.1604), and reach distances and opening sizes. You can use other standards, but you must show they reach the same level of safety or better.
All machinery should be reviewed against the standard — new, imported, old, or retrofitted.
| Type | How it works |
|---|---|
| Fixed guards | Physical barriers over nip points and moving parts, needing a tool to remove. The first choice where access is not needed during operation. |
| Interlocked guards | The machine cannot run, or stops, when the guard is opened. Must be designed so failure or loss of power does not expose anyone, and so the machine cannot restart with someone inside. |
| Presence-sensing | Light curtains, beams or pressure mats that stop the machine when the danger zone is entered. |
| Other devices | Two-hand controls, trip and emergency-stop devices, and distance guarding where higher-order guards are not practicable. |
Most serious machinery incidents trace back to a small set of failures: interlock mechanisms removed or overridden, light beams switched off, an interlock used as a shortcut to start the machine, ineffective lock-out and isolation, and supporting systems failing — for example a hydraulic or pneumatic system losing pressure and letting a ram fall. Guards being used as a start shortcut, or removed for cleaning and not replaced, are recurring patterns.
Guarding protects people during normal operation. For servicing, cleaning, unjamming and maintenance — when guards are opened or people reach in — you also need effective isolation so the machine cannot start unexpectedly. See energy isolation & lockout-tagout and plant & machinery safety. Specify guarding to AS/NZS 4024 when you buy or lease machinery, because retrofitting is far more expensive — see upstream duties.
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WorkSafe expects duty holders to use the AS/NZS 4024 Safety of Machinery series as the benchmark for safeguarding machinery and plant. Other standards can be used only if they achieve the same level of safety or better.
Fixed guards over nip points and moving parts, interlocked guards that stop the machine when opened, presence-sensing devices such as light curtains and mats, and devices like two-hand controls and emergency stops.
A guard linked to the machine controls so the machine cannot run, or stops, when the guard is opened. It must be designed to fail safely and to prevent the machine restarting with someone inside the guarded area.
Yes. All machinery should be reviewed against AS/NZS 4024, whether it is new, imported, old or retrofitted.
Usually because guards or interlocks are overridden or removed, light beams are switched off, interlocks are used as a start shortcut, isolation is ineffective, or a hydraulic or pneumatic system fails and lets a part fall.
