Energy isolation is one of those requirements that every manufacturer knows about but surprisingly few get fully right. Regulation 19 of PUWER makes the obligation clear: employers must provide suitable means of isolating work equipment from all its sources of energy, and reconnection must not expose anyone to risk. The Electricity at Work Regulations 1989 reinforce this specifically for electrical systems. And yet, when incidents involving unexpected start-up or energy release are investigated, the same gaps appear again and again.
This article looks at the most common shortfalls in energy isolation practice across UK and European manufacturing, and what safety leaders can do to close them.
What PUWER Actually Requires
Regulation 19 states that every employer shall ensure that, where appropriate, work equipment is provided with suitable means to isolate it from all its sources of energy. The accompanying Approved Code of Practice (L22) expands on this considerably. Isolation means establishing a secure break in the energy supply in a way that prevents inadvertent reconnection. This applies to all energy types: electrical, hydraulic, pneumatic, mechanical, thermal, gravitational and stored energy sources such as capacitors or compressed springs.
The ACOP guidance goes further. Where stored energy is present and capable of causing harm, a means of dissipating that energy must be provided. Visual tags and warning notices must be used at isolation points. Only the appointed person should be able to re-energise the equipment. And anyone affected by the equipment returning to a live state must be informed before reconnection.
Unlike the US OSHA standard (29 CFR 1910.147), which prescribes a specific annual periodic inspection regime with documented certification, PUWER’s framework is less prescriptive but arguably broader. The HSE expects employers to demonstrate that their isolation arrangements are adequate through risk assessment, that equipment is regularly inspected, and that workers are trained and competent. The flexibility is intentional, but it also means that organisations without a structured approach can drift into non-compliance without realising it.
The Three Gaps That Keep Appearing
1. Isolation procedures that exist on paper but not in practice
Many manufacturers have written isolation procedures, sometimes inherited from a previous safety manager, sometimes created during a compliance push several years ago. The problem is that these procedures often do not reflect the current configuration of the equipment they cover.
Machines get modified. New energy sources are added during upgrades. Isolation points are reconfigured when panels are relocated. If the written procedure still references the original layout, a technician following it could miss an active energy source entirely. The HSE has investigated numerous incidents where workers were injured because isolation was incomplete, typically because the procedure they were following was out of date.
The fix is a formal link between equipment modification and procedure review. Anytime a maintenance work order involves changes to a machine’s energy sources or isolation points, the corresponding procedure should be flagged for review before the next lockout.
2. No structured approach to lockout hardware
PUWER requires that isolation is secure and that inadvertent reconnection is prevented. In practice, this means physical lockout devices — padlocks, hasps, valve lockouts, circuit breaker lockouts — applied at each isolation point. The system of control must ensure that all locks are removed before the isolating device can be re-engaged, and keys must not be passed to anyone other than the nominated personnel.
What often happens in reality is more informal. A facility might have a collection of padlocks in a maintenance toolbox, but no standardised system for how they are issued, tracked or controlled. Locks might not be uniquely identifiable to individual workers. There might be no hasp arrangements for situations where multiple people need to lock out the same isolation point simultaneously. And in some cases, there are simply not enough lockout devices available to cover every energy type present on a given machine.
Getting the hardware right requires a deliberate audit of what isolation points exist across your equipment, what types of devices are needed, and whether you have sufficient stock to support concurrent maintenance activities.
3. Competency that is assumed rather than demonstrated
PUWER requires that only competent persons carry out isolation and de-energisation. The HSE does not provide a rigid definition of competency — it is expected to be proportionate to the complexity and risk of the task. But the expectation is clear: employers must be able to demonstrate that the person performing the isolation has the knowledge, training and experience to do it safely.
In many facilities, competency is assumed based on job title or tenure. A maintenance technician with 15 years of experience is assumed to know how to isolate any machine on the floor. But experience alone does not guarantee familiarity with every energy source on every piece of equipment, particularly after modifications or new installations.
The most effective approach is to link isolation competency to specific equipment or equipment categories, document it, and review it periodically. A digital lockout/tagout system can support this by tying procedure access to verified training records. But even without digital tools, the principle holds: competency for energy isolation should be specific, documented and current.
Bridging PUWER and OSHA
For manufacturers operating across both UK and US jurisdictions, it is worth understanding how the two frameworks differ. OSHA is more prescriptive: it requires machine-specific written procedures, mandates an annual periodic inspection by a different authorised employee, and demands certified documentation with specific fields. PUWER is goal-based — it requires you to achieve safe isolation but gives you more latitude in how you demonstrate it.
A programme designed to meet OSHA requirements will generally satisfy PUWER as well, but not always the other way around. If your organisation operates internationally, building your isolation programme to the more prescriptive OSHA standard while incorporating PUWER’s broader risk assessment expectations is typically the most efficient path.
Practical Takeaways
If you want to pressure-test your own arrangements, walk the plant floor and pick three machines at random. For each one, verify that the isolation procedure matches the machine’s current configuration. Check that the correct lockout hardware is available and in good condition. And confirm that the person who would perform the lockout has documented competency for that specific equipment.
If all three pass, your programme is solid. If any of them require a phone call, a trip to the filing cabinet, or a moment of uncertainty — that is the gap worth closing.
About the author
Matthew Nugent is a chemical engineer and co-founder of The Lock Box, a European distributor of lockout/tagout and emergency safety equipment, and Zentri, a digital lockout/tagout platform for projects & manufacturers.
