Confined Spaces
Confined spaces on construction sites β tanks, pits, trenches, tunnels β present unique hazards including atmospheric dangers. This topic covers confined space identification, atmospheric monitoring (oxygen levels, toxic gases, flammable vapours), entry permits, standby persons, rescue procedures, and the specific requirements under WHS Regulations.
Study Guide: Confined Spaces
Review these sample questions before starting the practice test.
Q1: Under the WHS Regulations, what defines a confined space?
- A. Any room smaller than 10 square metres
- B. Any underground area
- C. A locked storage container
- D. An enclosed or partially enclosed space not designed for human occupancy that may have a harmful atmosphere, engulfment risk, or restricted entry/exit β
The WHS Regulations define a confined space as an enclosed or partially enclosed space not designed or intended for human occupancy, with restricted entry/exit and risk of harmful atmosphere or engulfment.
Q2: Which Australian Standard specifically covers confined space entry?
- A. AS 1319
- B. AS 1940
- C. AS 2444
- D. AS 2865 β Confined Spaces β
AS 2865 (Confined Spaces) provides guidance on the safe entry, working, and rescue procedures for confined spaces, supplementing the WHS Regulations Part 4.3.
Q3: What is the normal oxygen level in breathable air?
- A. 15%
- B. 25%
- C. Approximately 20.9% β
- D. 30%
Normal atmospheric oxygen is approximately 20.9%. Entry into a confined space should not be permitted if the oxygen level is below 19.5% or above 23.5% without appropriate respiratory protection.
Q4: Before entering a confined space, what atmospheric testing is required?
- A. No testing is needed if the space looks clear
- B. A visual inspection only
- C. Only an oxygen test
- D. Testing for oxygen level, flammable gases, and toxic gases using a calibrated gas detector β
Before entry, atmospheric testing must check oxygen levels (19.5-23.5%), flammable gas concentrations (below 5% LEL), and toxic gases (below exposure limits) using a calibrated multi-gas detector.
Q5: What document must be completed before anyone enters a confined space?
- A. A building permit
- B. An insurance form
- C. A confined space entry permit β
- D. A time sheet
A confined space entry permit must be issued before entry. It records the hazard assessment, atmospheric test results, control measures, emergency procedures, and names of authorised entrants.
Q6: What is the role of a standby person (safety attendant) during confined space entry?
- A. To perform the work inside the space
- B. To go on lunch break while others work
- C. To complete paperwork in the site office
- D. To remain outside the confined space, monitor entrants, maintain communication, and initiate emergency rescue if needed β
The standby person remains outside the confined space at all times, monitors the condition of entrants, maintains continuous communication, and initiates emergency procedures if something goes wrong.
Q7: What is an oxygen-deficient atmosphere?
- A. An atmosphere with oxygen above 23.5%
- B. An atmosphere with no nitrogen
- C. Normal air
- D. An atmosphere with oxygen below 19.5% β
An oxygen-deficient atmosphere has an oxygen concentration below 19.5%. It can cause impaired judgement, loss of coordination, unconsciousness, and death. SCBA or airline respirators are required.
Q8: What does LEL stand for in atmospheric monitoring?
- A. Lowest Electrical Load
- B. Legal Exposure Limit
- C. Low Energy Level
- D. Lower Explosive Limit β the minimum concentration of a gas in air that can ignite β
LEL (Lower Explosive Limit) is the minimum concentration of a gas or vapour in air that can form an ignitable mixture. Confined spaces must not be entered if gas concentrations exceed 5% of the LEL.
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