Guarding, isolation and the controls that keep hands, fingers and lives intact
Machinery causes some of the most serious workplace injuries — amputations, crushing and worse. Under the HSWA you must manage the risks of plant: first try to eliminate the hazard, then guard it, and isolate (lock out) stored energy before anyone reaches into it. The AS/NZS 4024 standard is the recognised good practice, and designers, makers and suppliers share the duty.
Machines apply forces a human body can't withstand, and they don't stop for a careless moment.
The common machinery hazards — entanglement, crushing, cutting and shearing, being struck, and stored energy releasing unexpectedly — cause life-changing injuries. Unsafe or unguarded machinery has cost New Zealand workers fingers and hands and led to six-figure fines for the businesses involved. The reassuring part is that these injuries are highly preventable with the right controls in the right order.
Work down the hierarchy: remove the hazard, guard it, then rely on safe systems and training.
| Step | What it means |
|---|---|
| 1. Eliminate | Design out the hazard — can the dangerous part be removed, automated or accessed differently? |
| 2. Guard | Where you can't eliminate it, fit the correct guards and keep them in place — the primary machinery control. |
| 3. Safe systems | Isolation procedures, interlocks and prevention of unexpected start-up. |
| 4. Training & PPE | Competent operators, clear procedures, and PPE as the last layer. |
Emergency stops are an additional control, not a substitute for guards — and they don't isolate the machine, because they're part of the control circuit, not the energy supply.
Guarding is the workhorse of machine safety — when it's the right guard and it stays put.
A guard only protects people if it's correct for the hazard and remains in place during operation. WorkSafe points to the AS/NZS 4024 Safety of Machinery series as the current state of knowledge for safeguarding machinery and plant — covering risk assessment, the design of controls, interlocks and guarding, interlocking devices, and preventing unexpected start-up. You can use other standards, but you'd need to show they achieve an equivalent level of safety.
Most serious machinery incidents happen when someone reaches into a machine that wasn't properly isolated.
Before maintenance, cleaning, unblocking or any task that needs a guard removed or bypassed, the machine must be isolated and its stored energy controlled — so it can't start up or move unexpectedly. Have clear rules on when isolation is required (including for some cleaning tasks), a step-by-step lockout process, and a way to make sure no one can re-energise the machine while someone is working on it. This is where lockout/tagout earns its keep.
Safety is cheaper and better designed in than bolted on — which is why the law puts duties on the people who supply plant.
Under the HSWA, designers, manufacturers, importers and suppliers of plant must ensure, so far as is reasonably practicable, that it's without health and safety risks when used for its intended purpose — and during foreseeable tasks like cleaning, maintenance and repair. A poorly guarded machine creates a risk that flows downstream to every business and worker who uses it. (These upstream duties don't extend to second-hand plant sold as-is, so buyers of used machinery need to check it themselves.)
Plant registers, isolation procedures and checks in one place. Book a demo and we'll show you how it works — free 30-day trial included.
Entanglement, crushing, cutting and shearing, being struck, and the unexpected release of stored energy or start-up of the machine. These cause serious injuries like amputations, which is why guarding and isolation are so important.
The HSWA requires you to manage the risks of plant so far as is reasonably practicable. Where you can't eliminate a hazard, guarding is the recognised key control, and WorkSafe points to the AS/NZS 4024 Safety of Machinery series as the good-practice standard for safeguarding.
Lockout/tagout is isolating a machine and controlling its stored energy so it can't start or move while someone works on it. You need it before maintenance, cleaning, unblocking, or any task requiring a guard to be removed or bypassed. Some cleaning tasks need isolation even though they aren't maintenance.
No. An emergency stop is an additional control, not a substitute for a guard, and it does not isolate the machine — it's part of the control circuit, not the energy supply. To work safely on a machine you must isolate it and control its stored energy.
Yes. Designers, manufacturers, importers and suppliers must ensure, so far as is reasonably practicable, that plant is without health and safety risks for its intended use and foreseeable maintenance. Note these upstream duties don't extend to second-hand plant sold as-is, so check used machinery yourself.
