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What do I need in a Safe System of Work for Confined Space?

Once a risk assessment has been carried out (see our earlier risk assessment article) a safe system of work (SSoW) then needs to be devised.


confined space
confined space

The safe system of work for any given task is a formal procedure, laid out as a step by step set of instructions that documents the way in which a task should be carried out to ensure that it is undertaken safely.


The SSoW should take into account the risks that have been highlighted in the risk assessment, and clearly state how the control measures from the risk assessment will be used or implemented to keep the workers and the environment safe throughout the project. It should also detail how any tools or equipment in use are to be set up and operated. A simple example would be if a hard hat has been specified as a control measure in the risk assessment. Make sure that this is clearly stated in the safe system of work that a hard hat is part of the work crew’s personal protective equipment (PPE).

In a confined space, injuries are likely to be more severe and the injured person(s) more difficult to rescue - so it is important to work safely and the surest way of communicating essential information is through the use of a written safe system of work.

As defined in HSE ACOP L101 2014 for confined spaces, there are 20 points that, if each is carefully considered and accounted for, will produce a robust SSOW

  1. Supervision – how will the job be managed

  2. Competency – are those doing the work suitably trained

  3. Communications – how will accurate messages within the team be certain

  4. Testing the Atmosphere – is gas detection equipment required

  5. Gas Purging – does the vessel require flushing with an inert gas

  6. Ventilation – should forced venting be used, or is there sufficient natural venting

  7. Removal of Residues – is there existing material, such as sludge, needs taking out first

  8. Isolation from Flowing Material – is there protection against material flows, are these locked off

  9. Isolation from Electrical/Mechanical – is all live power isolated that should be

  10. Selection and Use of Suitable Equipment – ensure the entrants have the correct equipment to carry out their work task safely, consideration needs to be given as to whether intrinsically safe equipment is required

  11. Personal Protective Equipment – do the entrants require specific PPE to ensure their safety

  12. Gas Cylinders and Combustion Engines – have these been correctly isolated, including consideration for exhaust fumes if they will remain active

  13. Gas Supplied by Pipes – are there any gas supplies in the area that require protection or isolation

  14. Access and Egress – how will entrants get in and out of the confined space safely, particularly in an emergency

  15. Fire Prevention – what is being done to minimise fire risks, including suitable fire safety equipment

  16. Lighting – what is being done to ensure the entrants can see suitably, area lighting and task lighting

  17. Static Electricity – is this a hazard and what steps can be taken to prevent static build up

  18. Smoking – ensure that smoking areas which pose an ignition risk are not near to the worksite

  19. Emergency and Rescue Arrangements – how will the entrants get out of the confined space safely in the event of an emergency, will it be self-rescue or is a standby rescue required

  20. Limiting Work Time – do the conditions mean that working time should be limited to minimise worker fatigue, e.g. very warm environment or cramped working conditions

Breathe Safety are always keen to help. If you have any further questions feel free to speak to one of our team: 0330 828 0887 Follow us on our social media to be the first to know when the new blog posts come out.

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