Confined Spaces Classifications

Explanation of Low, Medium and High Risk

The two defining features of a confined space, according to regulation, are:

1) the space is enclosed and
2) the presence of a specified risk.

Upon identifying a confined space persons must undertake a risk assessment to determine the nature of specified hazards that could be encountered and the probability of encountering them. This will then lead to the classification of the confined space at low, medium or high risk and trigger the use of equipment and procedures appropriate to the confined space environment.

The terms ‘Low’, ‘Medium’ and ‘High’ risk confined space entry and the competency/training requirements for each are explained below.

Low Risk 

Low risk entries do not require the use of escape breathing apparatus, either because the risk of a hazardous atmosphere is very low or the time taken to get out of the space would be less than the time taken to don an escape set. Generally these entries will, be made by a single entrant, have simple and unobstructed entry/exit, have adequate natural ventilation, have no likely risk of flooding and may involve lone working. Training for Low Risk Entries

  •  Definition of a confined space and low, medium, high definitions
  •  Duties under the regulations, including preventing the need for entry and risk assessment
  •  Atmospheric hazards, gases and use of gas detectors
  •  Safe systems of work and permits to work
  •  Roles, responsibilities and topman / bottom man duties
  •  Inspection and use of tripods, winches, fall arrest equipment and harnesses
  •  Practical exercises and assessments

Medium Risk 

Medium risk entries require the use of escape breathing apparatus, either because the risk of a hazardous atmosphere is significant or the time taken to evacuate increases risk to entrants, ie distance travelled or where there is more than one entrant.There is a realistic expectation of encountering a specified risk either due to the intrinsic hazards within the space or the introduction of hazards due to work activity.There will always be one or more people - positioned outside the confined space - who have designated responsibilities for controlling the entry and dealing with emergencies. 

High Risk 

High risk entries are generally defined as those entries where full working breathing apparatus is required, either because there is a known hazardous atmosphere or because the likelihood/risks associated with a hazardous atmosphere occurring are significant. This may be due to intrinsic hazards within the space or introduced/task based hazards.

Other hazards including, the presence of heat, physical hazards (ie awkward/complex access, size restrictions) or other hazards may necessitate classifying the entry as high risk. High risk entries require the presence of personnel who have designated responsibilities for dealing with emergencies.