Wise manufacturers understand that effective machinery guarding is their first and best defence against machinery injuries. Notwithstanding this, too many machines are imported and installed in in the UK with machine guards that fail to meet the relevant ISO standards and so are not PUWER compliant. The lesson from a memorable enforcement case is clear: a new machine may seem to have guarding protection, but a single short tunnel guard can still be all it takes to cause operator injury and trigger a prosecution.
Why Tunnel Guards Matter: The Length Factor
Tunnel guards are a specific type of machine guard comprising a fixed barrier fitted around feed or input or discharge points so material can flow but distancing workers’ hands from the moving parts of a machine. Their effectiveness hinges on one design detail: length. If the guard does not extend far enough, it can be “defeated” by reaching round it or over it to the danger zone, so completely negating machine guarding effectiveness.
EN ISO 13857 lays out minimum reach-prevention distances; for example, a 50mm square opening must be at least 850mm from a hazard. When those calculations are ignored, guards become decorative rather than protective. In fact, in our view, they are worse than useless as they give a very false sense of security.
Imported Machinery: A Broader Compliance Challenge
Guarding issues on overseas-built machines are rarely limited to just tunnel guards. Across a range of industries we routinely find:
- Missing or underspecified perimeter fencing.
- Inadequate interlocking devices that can be bypassed.
- Insufficient and/or out of reach emergency stop controls.
- Electrical panels wired to out-of-date standards.
- CE or UKCA markings applied without proper evidence.
Regarding CE marketing, because the CE mark is often self-declared, UK duty-holders cannot assume that purchased machinery is actually compliant just because it has a certificate. PUWER obliges employers to inspect every new or second-hand machine before first use and put right any shortcomings. This responsibility extends beyond tunnel guards to encompass guarding and indeed all safety-critical systems.
Case Study: When Compliance Gaps Turn Critical
The Incident
We were called in after a UK soft toy manufacturer had installed an imported fibre-processing machine designed with a discharge system including a flange and full-length discharge chute. However, to accommodate their production layout, the company had modified the installation by removing the original discharge arrangement so as to fit allow faster material throughput. Although the device was still fitted with the tunnel guard provided by the machine’s manufacturer, it was short enough to still allow access to the spiked roller
The Critical Failure
The tunnel guard’s length fell short of EN ISO 13857 standard, creating a reach-through hazard that the original design had eliminated. When an operator attempted to clear a blockage, the inadequate guard failed its primary function and the rotating spiked roller caught their hand, resulting in severe injury.
The Legal Consequence
The subsequent HSE investigation revealed that the missing discharge chute and inadequate guard length created a foreseeable risk. The manufacturer had ignored this and in not fitting a suitable guard and ensuring CE marking, failed to meet the ISO standards. Because they were not compliant with PUWER the manufacturer was held accountable and fined accordingly.
The lesson: both systemic non-compliance and tunnel guard specifics contributed to a preventable accident. The company learned and its lesson the hard way. We reviewed the machine set up and how it was used and recommended a tunnel guard that was compliant without hindering effective machine operation.
Technical Requirements for Compliant Tunnel Guards
Effective tunnel guard design requires adherence to specific standards:
- Length Calculation: Safety distances must be determined using EN ISO 13857 tables, not simply estimated.
- Secure Construction: Fasteners used must require specific tools or be welded to deter removal (ISO 14120).
- Operational Integration: Guards should enable routine monitoring without creating bypass temptations.
- Interlock Compatibility: Where movable sections are necessary, ISO 14119:2025 mandates elimination of any “motivation to defeat” safety devices.
It is becoming the norm for modern tunnel guards to incorporate interlocking devices to prevent machine operation when guards are not properly positioned.
A Five-Point Compliance Framework for Effective Implementation
- Mandatory PUWER inspection on arrival. Treat every imported machine as high-risk until proven otherwise.
- Verify guard dimensions against standards. Measure all tunnel guards against EN ISO 13857 requirements and when needed.
- Comprehensive documentation. The Declaration of Conformity, technical file, and stop-time data for all interlocks should be readily available.
- Engage competent safety specialists. Use third-party surveys to identify compliance gaps efficiently and provide effective independent verification.
- Establish regular audit protocols. Guards can be damaged or simply deteriorate over time. To ensure PUWER compliance periodic re-inspection throughout the equipment lifecycle is necessary.
The Strategic Value of Proactive Compliance
Quality tunnel guard (and machine guarding in general) specification represents more than regulatory compliance. We’ve seen how manufacturers who take a responsible and proactive approach to machine guarding are able to demonstrate systematic risk management capability that in turn creates sustainable competitive advantages.
We consistently see that manufacturers who invest in comprehensive machine guarding compliance (including tunnel guards) and holistic machine safety upgrades consistently report:
- Reduced unplanned stoppages due to safety incidents and equipment damage.
- Enhanced operator confidence leading to optimum throughput and improved operator-employer relations.
- Lower maintenance costs through prevention of access-related equipment damage.
- Improved insurance positioning and smoother customer safety audits.
Moving Forward: A Systems Approach to Machinery Safety
Tunnel guards remain a frontline defence at feed and discharge points. There’s no flexibility in terms of the dimensional requirements. However, they must be viewed within the wider context of machinery guarding compliance.
Particular vigilance is required when it comes to installing imported machinery. Every imported machine must undergo rigorous PUWER assessment, as CE or UKCA marks provide limited assurance of UK compliance. This assessment extends beyond tunnel guards to encompass all guarding and electrical safety systems.
The case study demonstrates how a single inadequate tunnel guard can cause severe personal injury, trigger prosecution and incur significant financial consequences and reputational damage. Conversely, organisations prioritising comprehensive safety compliance from installation create sustainable competitive advantage through reduced risk exposure, improved operational reliability, and enhanced workforce confidence.
The evidence is compelling: proper tunnel guard specification together with imported machinery compliance are not optional, rather they are essential factors in achieving operational excellence. Fit the right guard, to the right standard, verify complete machine compliance and maintain UK manufacturing’s reputation for both productivity and safety.
Frequently Asked Questions
What is the main purpose of a tunnel guard? A tunnel guard is a fixed barrier fitted around a machine’s feed, input, or discharge points. Its primary purpose is to allow material to flow through while distancing workers’ hands from the hazardous moving parts of the machine.
Why is the length of a tunnel guard so important? A tunnel guard’s effectiveness is critically dependent on its length. If the guard is too short, an operator can still reach over or around it into the danger zone, which completely negates its protective function. To be compliant, its length must be calculated based on the safety distances specified in the EN ISO 13857 standard.
Does a CE or UKCA mark mean an imported machine is fully compliant in the UK? No, a CE or UKCA mark alone does not guarantee compliance. Because these marks are often self-declared, UK employers have a legal duty under PUWER to inspect every new machine before use to identify and correct any safety shortcomings. This responsibility covers all guarding, electrical, and safety-critical systems.
Contact us today to fins out more about tunnel guards and other machinery guarding solutions