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A safe system of work is a formal, planned way of doing a task that removes hazards where possible and controls the rest. It sets out who does what, in what order, with what equipment and precautions. Every employer is required to provide one, and on a construction site it is the thread that runs through risk assessments, method statements and permits to work.
The law behind it
- Health and Safety at Work etc. Act 1974, section 2(2)(a). Employers must provide and maintain plant and systems of work that are, so far as is reasonably practicable, safe and without risks to health.
- Section 2(2)(c). Employers must provide the information, instruction, training and supervision needed to make the system work.
- Management of Health and Safety at Work Regulations 1999. Regulation 3 requires the risk assessment that decides what the system must control, and regulation 5 requires arrangements to plan, organise, control, monitor and review preventive measures.
- Electricity at Work Regulations 1989. Regulations 12 to 14 require safe isolation, precautions on equipment made dead, and allow live work only where it is unreasonable for it to be dead, reasonable to work live, and suitable precautions are taken.
Our guide to the Management of Health and Safety at Work Regulations 1999 covers the management duties in more detail.
How it fits with RAMS and permits
| Document | What it does | How it relates to the safe system |
|---|---|---|
| Risk assessment | Identifies hazards and decides the controls | The starting point. It tells you what the system must control. |
| Method statement | Sets out the sequence of the task | Usually the written form of the safe system for a construction task. |
| Permit to work | Formally authorises high risk work and confirms precautions are in place | A tool within a safe system for the most dangerous jobs. HSE says a permit does not, by itself, make a job safe. |
| Safe system of work | The whole planned way of working | Combines people, equipment, environment, sequence and supervision. |
Read more in our guides to RAMS and permits to work.
How to develop a safe system of work
- Assess the task. Look at the people, the equipment, the materials and the environment. Use the risk assessment.
- Identify the hazards. Include what happens if something goes wrong, such as a rescue from a confined space.
- Define the safe method. Remove hazards where you can, then set out each step with its controls, using the hierarchy of controls.
- Implement it. Write it down where the risk justifies it, brief the team, provide equipment and supervise.
- Monitor and review. Check it is followed and works. Review after changes, incidents or near misses.
Worked example: cleaning out a site concrete mixer
A short example to show the parts of a safe system. A real one would match the actual mixer, its manual and the site.
| Element | Content |
|---|---|
| Task | Cleaning hardened concrete from the drum of a 110V electric site mixer at the end of each day. |
| Hazards | Entanglement in the rotating drum, electric shock, cement burns to skin and eyes, manual handling, noise from chipping. |
| Who can do it | Operatives trained on this mixer and briefed on this system. |
| Equipment and PPE | Lockable isolator or plug lock, padlock and danger tag, long handled scraper, waterproof gloves, eye protection, long sleeves, wellingtons. |
| Isolation | Switch off, unplug from the supply, fit a plug lock or lock the isolator, attach a danger tag, and try to start the mixer to prove it is dead. |
| Sequence | 1. Isolate and prove dead. 2. Rinse drum with water. 3. Remove loose material with the scraper from outside the drum. 4. Never put hands or tools in a rotating drum. 5. Remove lock only when the person who fitted it is satisfied all are clear. 6. Restore power and test run with guards in place. |
| Emergency | Eye wash station nearby, first aider known, cement on skin washed off immediately with clean water. |
| Supervision and review | Supervisor checks isolation is used. System reviewed if the mixer, location or team changes. |
A simple template
- Task and location
- Hazards identified
- Who is authorised and the competence needed
- Equipment, PPE and permits needed
- Isolation or other preparation
- Step by step sequence
- Emergency and rescue arrangements
- Supervision and monitoring
- Review date and triggers
- Briefing record
Situations that always need a defined safe system
- Work on or near electrical systems, including isolation and lock off
- Confined spaces
- Excavations near underground services, following HSE guidance HSG47
- Hot works
- Lone working, following HSE guidance INDG73
- Work on or near live traffic, railways or water
- Maintenance on plant and machinery
Training that helps
For managers who design safe systems, the NEBOSH Managing Risks course and IOSH Managing Safely both cover risk control in depth. For wider teams, our permit to work eLearning, lone working eLearning and electrical safety eLearning are quick online options.
Where this fits in SMSTS and SSSTS
Safe systems of work, permits and isolation are tested on both courses, and supervisors are expected to make sure the agreed system is followed. Our free SMSTS mock test and SSSTS mock test let you check your knowledge before the course or a refresher, and you can email yourself the results sheet at the end.
When you are ready, the five day SMSTS course is for site managers and the two day SSSTS course is for supervisors. If your certificate is due, the SMSTS refresher and SSSTS refresher keep it current.
Frequently asked questions
What is a safe system of work?
A planned, formal way of carrying out a task that removes hazards where possible and controls the remaining risks, setting out who does what, in what order and with what precautions.
Is a safe system of work a legal requirement?
Yes. Section 2(2)(a) of the Health and Safety at Work etc. Act 1974 requires employers to provide and maintain safe systems of work, so far as is reasonably practicable.
Is a safe system of work the same as a method statement?
Not quite. A method statement is usually the written form of the safe system for a task, but the system also includes training, supervision, equipment and monitoring.
Does every task need a written safe system?
No. Low risk tasks may only need simple instructions. The higher the risk, the more formal and detailed the system should be, up to a permit to work for the most hazardous jobs.
Read the source
The Health and Safety at Work etc. Act 1974, section 2; the Management of Health and Safety at Work Regulations 1999, regulations 3 and 5; the Electricity at Work Regulations 1989, regulations 12 to 14; HSE guidance HSG250 on permits to work, HSG253 on isolation, HSG47 on avoiding danger from underground services and INDG73 on lone working. Facts checked on 6 October 2026.
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