Confined Spaces

One of the highest-fatality work types. Most deaths are rescuers, not the original entrant. No entry without permit, atmospheric test, isolation, stand-by, rescue plan.

Bottom line

If a worker collapses in a confined space, the rescuer must NOT enter without air-supplied RPE. Most multiple-fatality events are sequential rescuers asphyxiating one after the other.

Quick Take

• Reg 4 definition: enclosed/partially enclosed; not designed for occupancy; risk of contaminants, O₂ outside 19.5–23.5%, engulfment, or restricted exit.
• Entry permit required every time — written, by competent person.
• Atmospheric test before entry: O₂ 19.5–23.5%, flammable < 5% LEL, contaminants below WES.
• Isolation by positive means — blanking, double-block-and-bleed, LOTO; not just closing a valve.
• Stand-by person outside, never in. Tested rescue plan ready.

1. Definition (Reg 4)

A confined space meets all four criteria:

1. Enclosed or partially enclosed.
2. Not designed or intended to be occupied by a person.
3. At normal atmospheric pressure when occupied.
4. Poses a risk from one or more of:
   • Atmosphere with potentially harmful contaminants.
   • O₂ deficiency or enrichment.
   • Engulfment in stored / free-flowing material.
   • Restricted means of entry/exit.

Examples: tanks, vessels, silos, pits, trenches > 1.5 m deep, ducts, sewers, underground wells, pipes, ceiling cavities, ships' holds, freight containers.

Classification follows the hazards present, not size. The same structure may or may not be a confined space depending on activity. Temporary controls (ventilation, monitoring) do not declassify — the space remains a confined space; controls just allow entry.

2. Identifying confined spaces

![[confined_spaces_img001.jpg|520]] Figure 1 — Confined-space determination flow. Walk every workplace; classify each candidate; sign and register.

Mandatory duties (Reg 34)

• Identify all confined spaces in the workplace.
• Register with hazards documented.
• Sign each entrance: warning against unauthorised entry.
• Barricade where practical (signage alone is not enough).
• Make register available to workers and HSRs.

Hazards are often invisible. Prior use is the strongest signal — what was stored or processed indicates likely contaminants, O₂ depletion, residue, or biological hazard.

3. Engulfment and bridging

![[confined_spaces_img002.jpg|520]] Figure 2 — Bridging hazard in silos: a crust of dry material forms over a void. Standing on the crust collapses it; the worker is buried in seconds. Common in silos containing grain, sand, sugar, fertiliser, sawdust.

4. Entry permit (Reg 67)

No entry without a written permit issued by a competent person.

Permit must include:

1. Space identification (location, unique reference).
2. Named entrants + authorised period.
3. Hazards from risk assessment.
4. Pre-entry controls: isolation, purging, ventilation, cleaning, signage.
5. During-work controls: continuous monitoring, PPE, RPE specifications.
6. Equipment exclusions (no ignition sources etc.).
7. Atmospheric test results (pass/fail).
8. Stand-by person identified.
9. Rescue equipment type + location.
10. Supervisor authorisation + entrant acknowledgement.
11. Exit sign-off — all persons and equipment accounted for.

Retention: until work complete, or 2 years post-incident if notifiable.

One permit = one space. Multiple entries to the same space may share one permit if conditions remain constant.

5. Atmospheric testing (Reg 71)

Pre-entry test, every time. Continuous monitoring during work.

Parameter	Acceptable
Oxygen	19.5–23.5% by volume
Flammable gas/vapour	< 5% of LEL absolute requirement
5–10% LEL	Exit unless continuous detector deployed
≥ 10% LEL	Immediate evacuation
Airborne contaminants	Below Workplace Exposure Standard (WES)

Purging (if required): use inert gas (nitrogen) — never pure O₂ or > 21% O₂ mixtures (extreme fire risk). Post-purge ventilation must restore O₂ to 21%. Re-test after purging.

6. Isolation (Reg 65)

A closed valve is not isolation. Isolation must be positive — physical, lockable, demonstrably blocking.

![[confined_spaces_img004.jpg|520]] Figure 3 — Pipe blanked with cap; nearest valve closed, locked, and tagged.

Approved methods (or equivalent)

1. Pipe removal: extract valve / spool / expansion joint near the space; blank or cap; tag for traceability.
2. Spade insertion (full-pressure spade/blank) between flanges near the space; tag purpose.
3. Double-block & bleed: close & lock two valves in series with a drain/vent valve locked open between them.

Mechanical / electrical ![[confined_spaces_img003.jpg|520]] Figure 4 — LOTO at all isolation points. Each entrant applies their own personal lock.

• LOTO every energised system with moving parts.
• Remove agitators, blades, or wedge / chain them immobilised.
• De-energise hydraulic, pneumatic, electrical, thermal, chemical stored energy.
• Keys held only by the worker who applied the lock; spares under controlled access.

7. Stand-by person (Reg 69)

One trained, competent stand-by person remains outside at all times.

![[confined_spaces_img005.jpg|520]] Figure 5 — Stand-by person with rescue equipment ready. Sign on the access. Never enters except for rescue, and only with appropriate RPE.

Duties:

• Continuous communication with entrants (voice, radio, hand signals).
• Monitor conditions; observe activity where practicable.
• Recognise distress signs (slurred speech, irregular breathing, collapse).
• Have rescue equipment immediately to hand (harness, lifeline, lifting gear).
• Authority to order evacuation if conditions change.
• Initiate emergency procedures and summon help.

No other work: full attention required.

8. Rescue plan (Reg 74)

Mandatory written plan. Tested. Never rely on emergency services as the primary mechanism.

Cover:

• Location accessibility; distance to medical care.
• Communications: how alarm is raised, 24/7 activation including night/weekend.
• Rescue equipment type, size, suitability; immediately accessible.
• Rescuer capability: training, fitness, BA / lifeline / equipment competency.
• Rescuer protection: air-supplied RPE if atmosphere is unsafe (assume unsafe if entrant unconscious from O₂ or contaminants).
• First aid: trained personnel, equipment on site.
• Pre-coordinated emergency-services arrangements (backup, not primary).

Rescue from outside the space wherever possible. If entry is required, rescuers wear air-supplied RPE.

Procedures must be rehearsed.

9. Training (Reg 76)

All relevant workers — entrants, stand-by, supervisors, rescuers — must be trained in:

1. Nature of hazards (O₂ depletion, contaminants, fire/explosion, engulfment, biological).
2. Why each control is essential and how to apply it.
3. PPE & RPE selection, fit-testing, use, storage, maintenance.
4. Permit content and what it means.
5. Emergency procedures, alarm activation, evacuation, rescue role-play, first aid.

Supervisors count as "relevant workers" — equivalent training.

Records: 2 years.

10. Common pitfalls / quick wins

Do

• Maintain a register of confined spaces; sign every entrance.
• Write standardised permits — laminate; one per space type.
• Test atmosphere every entry, even into spaces previously found "clean".
• Position rescue equipment outside every permitted space.
• Rehearse rescue annually with local emergency services.
• Use double-block-and-bleed — single-valve isolation has killed people.
• Continuous gas monitoring during occupancy with alarm to stand-by.

Don't

• Ventilate to "declassify" — the space stays classified.
• Let stand-by multitask. Full attention only.
• Let stand-by enter for rescue without air-supplied RPE.
• Rely on emergency services as the primary rescue mechanism.
• Use oxygen to ventilate — extreme fire risk.
• Skip the test because "we always work this tank" — conditions change.

11. Cross-references

• See also: [[excavation_work]] (deep trenches), [[welding_processes]] (welding inside vessels), [[managing_electrical_risks]] (LOTO of energised equipment)
• Foundations: [[risk_management_process]]
• Glossary (confined space, LEL, WES, BA): [[glossary_and_key_concepts]]

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Source: model_code_of_practice-confined_spaces-nov24.pdf (Safe Work Australia, model Code of Practice, CC-BY-NC 4.0). Edition: November 2024 (supersedes July 2020). Reg 4 definition, entry-permit and atmospheric-testing requirements carried forward unchanged. Last verified against SWA: 2026-04-28.