What Is a Confined Space?
A confined space is an enclosed or partially enclosed area not designed for continuous human occupancy, which has restricted entry or exit, and which may present specific hazards due to its configuration. Construction confined spaces include: excavations and trenches; manholes and vaults; tanks and vessels; crawl spaces under buildings; and enclosed ductwork. The hazards associated with confined spaces — oxygen deficiency, toxic or flammable atmospheres, engulfment, and restricted rescue access — have caused many deaths and serious injuries in the construction industry.
The Health and Safety at Work (General Risk and Workplace Management) Regulations 2016 set out requirements for managing confined space hazards. WorkSafe’s guidance on confined space work provides detailed practical guidance on safe working procedures.
The Safe Entry Permit System
A confined space entry permit is a documented authorisation system that ensures that every confined space entry is properly planned, that hazards have been identified and managed, and that emergency rescue arrangements are in place before anyone enters. The permit system requires: identification of the specific confined space and the work to be done; assessment of the hazards present; specification of the controls to manage those hazards (atmospheric testing, ventilation, personal protective equipment, rescue equipment); and sign-off by a competent person before entry.
Atmospheric Hazards
The most immediately life-threatening confined space hazards are atmospheric: oxygen-deficient atmospheres (below 19.5% oxygen) cause rapid incapacitation and death; toxic gases (hydrogen sulphide in sewers, carbon monoxide from combustion) are extremely dangerous; and flammable atmospheres can ignite. Before entering any confined space where atmospheric hazards might be present, the atmosphere must be tested using a calibrated multi-gas detector, and the result must confirm safe conditions before entry proceeds.