HomeHSG141 Electrical Safety on Construction Sites
HSG141 is an HSE guidance publication on electrical safety on construction sites. It explains practical ways of meeting health and safety duties under the law. Following HSE guidance is not compulsory, but if you do follow it you will normally be doing enough to comply with the law, and HSE inspectors may refer to it when considering compliance. You can read the full HSG141 guidance here.
The guidance is aimed at those planning, managing, installing, maintaining and using electrical systems and equipment on site. It covers projects of all sizes, including new build, refurbishment and demolition. Importantly, it is not limited to portable tools and appliances. It also covers temporary distribution systems, existing electrical services in buildings, and the commissioning of permanent installations.
For PAT testing purposes, the value is that it places portable equipment into the wider picture of site electrical safety. The message is simple: inspection and testing matter, but so do equipment choice, safe supplies, cable protection, and day-to-day maintenance.
Choose safer equipment first
A key theme is reducing risk at source. Battery-operated tools are often the safest option, and they also remove trailing leads and extension cables. Battery charging still needs planning, whether that’s RCD-protected sockets on smaller sites or dedicated charging points on larger ones.
Where battery tools are not suitable, the guidance favours 110V reduced low-voltage systems. Using a 110V site transformer significantly reduces shock risk compared with standard 230V supplies, which is why 110V is widely used for portable tools on construction sites. For practical details (including testers, adaptors and what to watch for), see our article on PAT testing 110V equipment.
This doesn’t mean 230V tools must never be used, but they should not be the default choice where safer alternatives are practical. Where 230V portable tools are the only realistic option, extra precautions are needed because the potential severity of injury is greater if something goes wrong. Suitable RCD protection should be used, and RCDs should be checked daily using the test button.
Equipment must suit site conditions
Only equipment appropriate for a construction site should be used. The guidance warns against poor practices such as using twin and earth cable as an extension lead, using unsuitable standard 230V accessories, or allowing cables to remain exposed where they can be damaged or become a trip hazard.
Equipment should also be robust enough for the environment, with an IP rating suitable for the location and conditions, especially where dust or water may be present.
Maintenance and PAT testing
Portable tools used on site should be maintained so they remain safe, and inspection and testing intervals should be proportionate to the risks present. See our guide to carrying out a risk assessment for PAT testing frequency to help determine suitable inspection and test intervals.
Maintenance is best thought of as a combination of user checks, formal visual inspections, and combined inspection and testing. User checks are especially important on construction sites because equipment can be damaged between scheduled inspections. For more details, see our guide to user checks.
Damaged equipment must be taken out of use
Defective tools and equipment should be removed from use. Extension leads are commonly found to be damaged, and repairs often require specialist knowledge. In many cases, replacement is more appropriate than repair.
This aligns with good site PAT practice: the aim is not to “keep everything in service”, but to identify unsafe items and get them out of circulation quickly.
Generators and Class I / Class II equipment
The guidance also covers small single-phase generators used for remote tasks. It favours 110V reduced low-voltage supplies and/or double-insulated Class II equipment. Placing the generator close to the point of work reduces the need for extension leads and lowers the risk of cable damage.
Where Class I equipment is used with a small generator, only one item should be connected unless each circuit has RCD protection. For more background, see our article on Class I and Class II equipment.
Why frequent testing makes in-house skills worthwhile
Construction sites are hard on electrical equipment. Tools and leads are moved constantly, cables get trapped or crushed, and plugs and connectors take a lot of abuse. Because of this, inspection and testing is typically carried out far more often than in low-risk environments such as offices. In practice, many sites work to short test cycles (often around every 3 months for portable tools, leads and 110V equipment), backed up by frequent user checks.
Where testing is needed this often, being able to carry out inspection and testing in-house makes a lot of sense. It allows faults to be dealt with immediately, reduces downtime waiting for a contractor, and gives better control over records and defect management. If you’re looking to build that capability, our PAT testing courses are designed to give practical, hands-on competence rather than just theory.
Final thoughts
The overall approach is practical and risk-led. It’s not just about testing tools, but about choosing safer equipment first, using 110V or battery tools where possible, controlling the use of 230V equipment, protecting cables, inspecting equipment regularly and removing damaged items from use.