What is L101?
L101 is the HSE's Approved Code of Practice (ACOP) and guidance for the Confined Spaces Regulations 1997. It provides detailed practical guidance on how to comply with the legal requirements for safe work in confined spaces.
A confined space is any place that is substantially enclosed (though not always entirely) where serious injury can occur from hazardous substances or conditions within the space or nearby. Examples include storage tanks, silos, reaction vessels, enclosed drains, sewers, open-topped chambers, ductwork, and poorly ventilated rooms.
Every year, people are killed or seriously injured in confined spaces in the UK. Many of these deaths also involve would-be rescuers who enter without proper equipment or training. L101 provides the framework to prevent these tragedies.
Who Needs This Document?
L101 is essential reading for:
- Employers whose workers enter or work in confined spaces
- Self-employed persons who work in confined spaces
- Managers and supervisors responsible for planning and overseeing confined space work
- Health and safety professionals advising on confined space procedures
- Contractors carrying out work in tanks, vessels, sewers, and similar spaces
- Facilities managers responsible for buildings with confined spaces
- Water and utilities companies with staff working in sewers, chambers, and tanks
- Manufacturing and process industries using vessels, silos, and enclosed plant
- Construction companies working on sites with excavations, tunnels, and enclosed areas
Key Topics Covered
Identifying Confined Spaces
L101 explains how to identify a confined space. It is not just about size - a confined space is defined by the risks present, not dimensions. Key indicators include:
- Substantially enclosed spaces
- Risk of serious injury from hazardous substances (gases, vapours, liquids)
- Risk from lack of oxygen or oxygen enrichment
- Risk of fire or explosion
- Risk of free-flowing solids causing engulfment
- Risk from high temperatures
Risk Assessment
Before any work in a confined space, a suitable and sufficient risk assessment must be completed. L101 guides you through:
- Identifying the hazards specific to the space
- Evaluating who might be harmed
- Determining what precautions are needed
- Recording the assessment
- Reviewing and updating as circumstances change
Avoiding Entry Where Possible
The Regulations require that entry to confined spaces is avoided wherever reasonably practicable. L101 provides guidance on:
- Modifying the work so entry is not required
- Using remote equipment, cameras, or long-reach tools
- Designing out the need for entry in new installations
Safe Systems of Work
Where entry cannot be avoided, a safe system of work must be in place. L101 covers:
- Appointment of competent supervisors
- Competence and training of workers
- Isolation procedures (mechanical, electrical, process)
- Atmospheric testing and monitoring
- Ventilation requirements
- Use of suitable breathing apparatus
- Personal protective equipment
- Communications systems
- Permit-to-work systems
Emergency and Rescue Arrangements
A critical requirement is having suitable emergency and rescue arrangements in place before work begins. L101 details:
- Planning for foreseeable emergencies
- Rescue equipment and its positioning
- Training rescue personnel
- Raising the alarm procedures
- First aid arrangements
- Never entering to attempt rescue without proper equipment
Legal Status
L101 has special legal status as an Approved Code of Practice. While not the law itself, following the ACOP provides a clear route to compliance with the Confined Spaces Regulations 1997. If you are prosecuted for a breach of the Regulations and it is proved that you did not follow the relevant provisions of the ACOP, a court will find you at fault unless you can show you complied with the law in some other way.
In practical terms: follow L101 and you are very likely complying with the law. Deviate from L101 without good reason and documented alternatives, and you may struggle to defend yourself if something goes wrong.
Why It Matters
Confined space incidents are among the most deadly in occupational health and safety. Key statistics:
- Around 15 people are killed each year in the UK in confined space incidents
- Many fatalities involve would-be rescuers who attempt to save a colleague without proper equipment
- Atmospheric hazards (toxic gas, lack of oxygen) are the most common cause of death
- Incidents often happen in spaces people do not recognise as confined spaces
The consequences of getting confined space work wrong can be:
- Fatal injuries to workers and rescuers
- Serious criminal prosecution of individuals and companies
- Unlimited fines and potential imprisonment for gross negligence
- Destruction of business reputation and loss of contracts
- Civil claims from injured workers and their families
L101 provides the blueprint for preventing these outcomes. By following its guidance, you can ensure work in confined spaces is planned, managed, and executed safely.
Key Requirements Summary
| Requirement | What L101 Says |
|---|---|
| Avoid entry | Do not enter a confined space if the work can be done another way |
| Risk assessment | Complete a specific assessment for the confined space and task |
| Safe system of work | Establish procedures covering isolation, atmosphere, PPE, and supervision |
| Competence | Only competent, trained personnel should enter or supervise |
| Emergency arrangements | Have rescue procedures and equipment ready before entry |
| Permits | Use permit-to-work systems for higher-risk entries |
Further Resources
- Confined Spaces Regulations 1997 (legislation.gov.uk)
- HSE Confined Spaces web pages
- INDG258 - Safe work in confined spaces (free leaflet)
This page summarises the ACOP L101. For full legal compliance, obtain and read the complete document from HSE. This summary is not a substitute for professional advice or the full ACOP text.