Legal considerations when fitting a safety light curtain to used machinery

A safety light curtain can make an older press, conveyor, punch, or packaging machine safer by detecting entry into a hazardous zone and sending a stop signal. On a used machine, however, installing the sensor is a risk-control project rather than a simple electrical upgrade. The machine’s original design, control system, guarding, stopping time, and operating procedures all affect whether the safeguard is legally defensible.

Australian businesses must manage machinery risks under work health and safety or occupational health and safety legislation. The applicable rules depend on the state or territory where the equipment operates. New South Wales, Queensland, South Australia, Tasmania, the Australian Capital Territory and the Northern Territory broadly follow the model WHS framework, while Victoria and Western Australia apply separate legislation and regulators.

A light curtain may reduce access to a danger point, but it does not automatically make a machine compliant. A poorly positioned device can leave a gap, allow a person to reach the hazard before the machine stops, or create unexpected restart risks. Used equipment may also contain undocumented modifications, obsolete relays, damaged wiring, or control logic that cannot reliably accept a protective stop command.

For that reason, the project should combine engineering assessment, legal review, electrical verification and worker consultation. The aim is to show that risks were identified, controls were selected using the hierarchy of controls, and the completed safeguard performs as intended throughout normal production, cleaning, maintenance and fault conditions.

Identify the duty holder and machine history

The business that operates the equipment generally has the primary duty to provide and maintain a safe work environment. Officers may also have due diligence obligations, while designers, manufacturers, importers, suppliers and installers can carry responsibilities connected with the machine’s design and supply. These duties can overlap when a company buys a used machine and then substantially modifies it.

Begin by collecting the machine’s make, model, serial number, age, previous use, manuals, electrical drawings, declarations and maintenance records. Confirm whether the machine was imported, rebuilt, relocated or previously fitted with guards. A second-hand machine without reliable documentation should be treated as requiring a fresh risk assessment rather than being presumed safe because it operated elsewhere.

State regulators can issue improvement or prohibition notices where guarding or control measures are inadequate. Keeping a written decision trail helps demonstrate that the business considered foreseeable misuse, access by contractors, operator training and changes in production. The file should explain why a light curtain was selected and identify any remaining risks that require other controls.

Apply Australian machinery safety standards

The AS 4024 series is a key reference for safeguarding industrial machinery in Australia. Relevant parts address general safety principles, guards, presence-sensing protective equipment, safety distances and control-system performance. International standards such as ISO 13849-1 and IEC 62061 may also help determine the required performance level or safety integrity level for the protective function.

Standards are not legislation in themselves, but regulators, engineers and courts may regard them as evidence of reasonably practicable risk control. The current edition and scope should be checked for the particular machine. A risk assessment may reveal that the curtain must achieve a specified safety performance, use monitored dual-channel circuits, or connect to a safety-rated controller rather than an ordinary programmable relay.

Electrical work must also be considered. Emergency stops, isolation, protective bonding, control panels and machine wiring may fall within requirements referenced by AS/NZS 60204.1 and state electrical rules. A licensed electrician or competent machinery safety professional should verify the installation, especially where the retrofit changes a switchboard, safety relay, motor control circuit or variable-speed drive.

Calculate stopping distance and safe placement

The curtain must be positioned far enough from the hazard that a person cannot reach the danger point before hazardous motion has stopped. This requires measuring total stopping time, including sensor response, safety-controller processing, contactor or drive delay and the mechanical stopping time of the machine. The required separation distance also depends on the approach speed used in the relevant calculation.

A common mistake is to measure only the distance from the beam to the die or blade. Operators may reach between beams, over the top, around the side or through an opening below the sensing field. Resolution, beam spacing, mounting height, machine layout and foreseeable body access all matter. A safety assessment should consider whether a person can remain inside the protected area without being detected.

Stopping performance can deteriorate with worn brakes, pressure changes, product loads, temperature or drive faults. Test results should therefore reflect realistic operating conditions, including the worst credible cycle. The test instrument, method, measured times and final safety distance should be recorded and repeated after significant maintenance or control-system changes.

Design the protective stop correctly

A light curtain is only one part of a safety function. Its output should initiate a controlled stop that prevents access to the hazard, and the circuit should detect faults such as a welded contactor, broken wire or failed safety relay. Automatic restart after the beam is restored is usually unsafe where a person could still be exposed, so a separate, deliberately operated reset may be required from a location with clear visibility.

For complex machinery, a safety-rated programmable controller may coordinate the curtain with gates, emergency stops, muting devices and mode selection. Muting is particularly sensitive: it should operate only when the movement of materials genuinely requires it, with appropriate timing, sensors and anti-tamper measures. Bypassing or masking the device for convenience can create a foreseeable dangerous practice.

Where a specialist assessment is needed, a local engineering or automation provider can help review the proposed architecture and commissioning evidence. Businesses exploring digital upgrades may also find value in automation guidance when integrating a protective device with existing production controls without sacrificing safety functions.

Manage isolation, access and maintenance

Workers must be able to isolate all relevant energy sources before cleaning, clearing jams, setting tooling or repairing the machine. This can include electrical, pneumatic, hydraulic, gravitational, thermal and stored mechanical energy. A light curtain does not replace lockout and isolation because it may be bypassed, defeated or unable to control energy that remains stored in the equipment.

Isolation points should be clearly identified, lockable and covered by a documented procedure. The procedure should state how to stop the machine, isolate supplies, dissipate stored energy, verify zero energy and return the equipment to service. In Australia, everyday practices vary between a small workshop in Adelaide, a food plant in Melbourne and a logistics operation in Sydney, but the need for effective isolation remains the same.

The risk assessment should address foreseeable bypassing. Operators may tape over a sensor, enter through an unprotected side or use a maintenance mode incorrectly if the safeguard interrupts production too often. Physical fixed guards, interlocked gates, suitable access arrangements and task-specific training may be needed alongside the light curtain.

Verify the retrofit and train workers

Commissioning should include functional tests for beam interruption, power loss, reset behaviour, restart prevention, fault detection and emergency stopping. Test every access route and operating mode, including manual, setup, automatic and fault recovery modes. Confirm that the machine cannot restart when a person is in a protected area or when the curtain is blocked.

A competent person should sign off the risk assessment, electrical checks, safety-function validation and operator instructions. The business should retain drawings, component specifications, software versions, test records, training attendance and corrective actions. In Victoria, where the Occupational Health and Safety Act 2004 applies rather than the model WHS laws, this evidence remains valuable for demonstrating systematic risk management.

Training should explain the purpose and limitations of the safeguard rather than presenting it as an invisible wall. Workers need to know how to report nuisance trips, damaged components and unusual stopping behaviour. Contractors and labour-hire personnel should receive equivalent information before operating or servicing the machine.

Consider procurement, funding and digital integration

When buying a used machine, put safety requirements into the purchase contract. Require disclosure of modifications, available technical files, known faults and previous incidents. Budget for guarding, control upgrades, isolation hardware, validation and training instead of treating the purchase price as the full cost of ownership.

A light curtain can also produce useful status data, but production monitoring must not weaken the safety circuit. For example, event logging may help identify repeated interruptions or maintenance needs, while the protective stop should remain independent from ordinary productivity software. Digital transformation projects should separate safety-rated functions from convenience automation and cybersecurity controls.

Small and medium-sized businesses can investigate practical support through local programs that connect companies with vetted automation providers and subsidy pathways. Workshops on factory digital transformation, IT investment and online efficiency can help managers compare implementation options. A low-code workshop illustrates how digital tools can improve administration, although safety functions require specialist engineering validation rather than ordinary workflow automation.

Australian market conditions also influence the project. A regional manufacturer may rely on a local electrician and interstate spare-parts supplier, while a Sydney or Brisbane business may need to coordinate installation around continuous shifts and contractor access. Choosing supported components, documenting equivalent replacements and planning periodic testing can reduce downtime when imported equipment becomes difficult to service.

A used machine retrofit should proceed only after the hazard assessment, legal duties, safety distance, control architecture and validation plan are clear. Businesses seeking an assessment or implementation pathway can contact the program team to discuss automation support, provider matching and possible funding options. Have the machine records, photographs, control drawings and proposed production changes ready so the review can focus on practical, verifiable risk reduction.