PUWER – Combat confusion re control systems

Obligations under PUWER are well accepted across industry believes Mark Smailes, Managing Director of Safety Systems Technology. Here he highlights a worrying tendency where companies believe that it’s not necessary to update the control systems of work equipment in response to PUWER assessments. A belief that, as Mark writes below, has absolutely no justification and is potentially dangerous.

 Most companies now understand that all work equipment is covered by the Provision and Use of Work Equipment Regulations 1998 – usually known simply as PUWER – and that these wide-ranging regulations are designed to ensure that work equipment is safe for use. Nevertheless, it is worth reiterating that PUWER assessment is not a one-off process. The assessment must be repeated at appropriate intervals, and it always refers to the latest standards and not, for example, to the standards that may have been applicable when the equipment was first brought into service.

Regulation 6 of PUWER requires equipment to be inspected after installation and before being put into service, and also after assembly at a new site or in a new location. In addition, for equipment that is exposed to conditions causing deterioration, inspection is also required “at suitable intervals” and each time that exceptional circumstances liable to jeopardise the safety of the equipment have occurred.

Since almost all work equipment is subject to wear and tear, which can be interpreted as “conditions causing deterioration” it is clear that regular PUWER assessments are essential. In reality the majority of companies comply – at least on the face of it – with this requirement. The result is that the machines themselves are regularly upgraded to comply with the latest standards. Typical upgrades include enhanced guarding arrangements, the addition of more safety sensors and simple improvements.

Unfortunately, there’s an important part of the machine that’s hidden away and, at least partly for this reason, is often overlooked. This is, of course, the control system. It’s not always simply a case of “out of sight, out of mind” however – there are companies that genuinely believe it is unnecessary to upgrade control systems and even safety-related control systems as part of the PUWER compliance process.

Quite why this belief has taken hold is hard to understand, as PUWER clearly covers these aspects of machinery in some detail, in the following regulations: Regulation 14 – Controls for starting or making a significant change in operating conditions; Regulation 15 – Stop controls; Regulation 16 – Emergency stop controls; Regulation 17 – Controls; Regulation 18 – Control systems; Regulation 19 – Isolation from sources of energy.

These six regulations clearly lay down minimum requirements relating to how work equipment should be controlled and operated, as well as how any safety-related control system for the equipment should work. PUWER inspections carried out in line with Regulation 6 must therefore include an assessment of whether the requirements of Regulations 14 to 19 are met. If they are not, then the control system and safety related control must be upgraded to ensure legal compliance with PUWER.

Put bluntly, a new guard or an extra safety mat installed as the result of a PUWER assessment may indeed enhance the safety of a machine, but the machine is still not PUWER compliant unless the control system has also been assessed and all necessary improvements made.

When assessing control systems, close attention to Regulation 18 of PUWER and the associated guidance notes is necessary. This regulation primarily requires employers to ensure that, so far as is reasonably practicable, all control systems are safe, and that they are chosen making due allowance for the failures, faults and constraints to be expected in the planned circumstances of use.

It is worth noting that, although not explicitly stated in the regulation, the control system should maximise safety not only for those operating the machine, but also for anyone else who may work on it including, for example, maintenance staff who may find it necessary to directly access the components making up the control system.

Regulation 18 also requires that the operation of the control system shall not create any increased risk to health and safety, and – significantly – that, as far as is reasonably practicable, any fault or damage to the control system or loss of supply … cannot result in additional or increased risk to health and safety. The final requirement of this regulation is that the control system shall not impede the operation of any control associated with the machine stop or emergency stop functions.

The guidance notes directly associated with Regulation 18 are numbered 267, 268, 269 and 270. Notes 267 and 268 deal principally with definitions, but 269 is rather more interesting as it discusses the fail-safe behaviour of control systems. While the concept of such behaviour may seem obvious, the note points out that fail-safe operation is not always the same as bringing a machine to an immediate stop. Halting some chemical processes, for example, can create more hazards than allowing them to continue.

Finally, Note 270 states that there are many national, European and international standards that relate to control systems, and mentions in particular BS EN 60204-1 and BS EN ISO 13849-1:2006, both of which provide invaluable guidance on the design of control systems to maximise their performance in relation to safety. The standards are, of course, aimed at new machinery, but they may nevertheless be used a guide to the performance that should be expected when carrying out PUWER assessments on the control systems of existing work equipment.

To summarise, it’s never acceptable to ignore a machine’s control system when conducting PUWER assessments. Making visible modifications to enhance the safety of a machine may give the feeling of a job well done, but it can also create a false sense of security if the control system is not up to the task required of it – fitting a new guard, for example, won’t compensate for an inadequate control system!

Though assessing control systems may seem daunting, we’ve seen that the PUWER regulations themselves – to which direct reference should always be made when carrying out assessments – contain a lot of useful information and guidance.

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