What is a Confined Space

Understanding Confined Spaces in Victoria

In Victoria, a confined space is defined under Part 3.4 of the Occupational Health and Safety Regulations 2017 (OHS Regulations). Identifying whether a space meets this definition is critical, as confined spaces require specific safety procedures, including permits, atmospheric testing, and emergency planning.

For a space to be legally classified as a confined space under Victorian law, it must meet all of the following criteria:

1. The space is not designed or intended primarily for human occupancy

  • The space is designed for purposes other than regular human presence.
  • Common examples include tanks used for liquid storage, sewers for waste flow, or silos for grain.
  • While workers may need to enter for maintenance or repairs, the space is not meant for continuous occupation.

2. The space has restricted means of entry and exit

  • Entry and exit points may be small, narrow, or require the use of ladders or confined openings.
  • Consideration should be given to whether it would be difficult to remove an unconscious person in an emergency. If rescue or emergency evacuation would be hindered by restricted access, this may indicate the space is confined.

3. The space is entered at atmospheric pressure

  • A confined space must be at normal atmospheric pressure while a person is inside.
  • Spaces that are pressurized or operate under a vacuum whilst a person is inside, are not classified as confined spaces under this definition.

4. The space presents a risk to health and safety from one or more of the following hazards:

A confined space must have a specific hazard that could endanger workers, including:

  • Unsafe oxygen levels
  • Harmful airborne contaminants (e.g., toxic gases, vapours, dusts)
  • Engulfment risks (e.g., liquids, flowing solids such as grain or sand)

If a space meets all four criteria, it is legally classified as a confined space, meaning that specific safety controls must be implemented. If any one of the criteria is not met, the space may still be hazardous, but it is not legally considered a confined space under Victorian law.

Breaking Down Confined Space Hazards

1. Unsafe Oxygen Levels

Oxygen levels in the air are critical for breathing and bodily function. WorkSafe Victoria defines safe oxygen levels as between 19.5% and 23.5%. Anything outside this range is unsafe.

Low Oxygen (<19.5%) – Oxygen Deficiency

  • Can cause dizziness, confusion, loss of consciousness, and death.
  • Causes include:
    • Rusting or corrosion of metals inside the space (which consumes oxygen).
    • Decomposing organic material (e.g., waste in a sewer).
    • Displacement by other gases (e.g., nitrogen leaks).

High Oxygen (>23.5%) – Oxygen Enrichment

  • Increases the risk of fire, as materials burn more readily in a high-oxygen environment.
  • Causes include:
    • Leaking oxygen cylinders.
    • Certain chemical reactions inside the space.

2. Airborne Contaminants

These include toxic, irritant, or suffocating gases that can cause illness or death. Common examples include:

  • Carbon monoxide (CO) – A colourless, odourless gas that can cause poisoning or death at high levels.
  • Hydrogen sulfide (H₂S) – Found in sewers; smells like rotten eggs at low levels but can numb the sense of smell and be fatal at high concentrations.
  • Solvents and fumes – Used in cleaning or painting processes, leading to dizziness, nausea, and nerve damage.

3. Engulfment Risks

Engulfment occurs when a worker is trapped, buried, or drowned inside a confined space due to:

  • Flowing solids collapsing (e.g., grain, sand, sugar).

Engulfment does not necessarily mean total burial—even partial burial can trap a person and make escape impossible.

How to Determine if a Space is a Confined Space

Step 1: Apply the Four-Part Definition

Ask:

  1. Is it not designed for human occupancy?
  2. Is access restricted, and would it be difficult to remove an unconscious person?
  3. Is it entered at atmospheric pressure?
  4. Does it contain one or more confined space hazards?

If all four apply, it is a confined space under Victorian law.

Step 2: Conduct a Risk Assessment

Even if a space is not legally a confined space, it may still be dangerous. Employers should conduct a risk assessment to determine the best safety controls.

Step 3: Check if Confined Space Entry Requirements Apply

If a space is determined to be a confined space, the following apply:

  • A Confined Space Entry Permit is required before entry.
  • Atmospheric testing must be conducted.
  • A trained standby person must monitor workers inside the space.
  • Emergency rescue procedures must be in place.

Final Thoughts

Understanding what defines a confined space in Victoria is essential for workplace safety. A confined space must meet all four legal criteria, including restricted entry, being at atmospheric pressure, and the presence of hazardous conditions.

Employers must conduct proper risk assessments, use gas monitoring, and follow legal entry requirements to prevent injuries and fatalities in confined spaces. By following WorkSafe Victoria’s guidelines, businesses can ensure compliance with the law and protect workers from life-threatening hazards.