A confined space is any enclosed or partially enclosed area that is not designed for continuous worker occupancy and has restricted means of entry or exit. Examples include storage tanks, silos, sewers, tunnels, vessels, manholes, and underground vaults.
Primary hazards
- Oxygen deficiency or enrichment
- Flammable or toxic gases
- Engulfment (grain, liquids, loose material)
- Entrapment due to converging walls or sloping floors
- Restricted movement during emergencies
Required controls
Entry typically requires a permit-to-work system, atmospheric monitoring, trained attendants outside the space, reliable communication, and a documented rescue plan that does not rely on calling 999.
UK regulations
Governed by the Confined Spaces Regulations 1997 and supported by HSE guidance L101.