What counts as a confined space, and why a trench usually does not

The test has three limbs, and the third one carries four risks

WHS Regulation 5 defines a confined space as an enclosed or partially enclosed space that:

• is not designed or intended to be occupied by a person
• is, or is designed or intended to be, at normal atmospheric pressure while any person is in the space, and
• is or is likely to be a risk to health and safety from an atmosphere without a safe oxygen level, from contaminants that may cause injury from fire or explosion, from harmful concentrations of airborne contaminants, or from engulfment.

Note what is absent: any reference to size, to headroom, or to how hard the space is to get out of. A cramped crawl space with clean air and no engulfment risk is not a confined space under this definition. A large tank that has held solvent is.

The line that catches people out

The Code puts the principle plainly: A confined space is determined by the hazards associated with a set of specific circumstances and not just because work is performed in a small space.

Read that as an operational instruction rather than a definition. It means the classification is not a property you can paint on a structure once and file. The Code says the same thing from the other direction: the same structure may or may not be a confined space depending on the circumstances when it is entered. A silo that is safe when empty and ventilated is a different proposition after a load of grain goes in.

What is not a confined space, including the one that surprises people

The Code lists exclusions. A mine shaft or the workings of a mine is not a confined space for these purposes. Nor are places intended for human occupancy with adequate ventilation, lighting and safe entry and exit. Nor, generally, are spaces designed to be occasionally occupied where there is a readily and conveniently accessible means of entry and exit via a doorway at ground level, and the Code's own examples are a cool store entered by forklift and a fumigated shipping container with a large ground level opening. In both, the reasoning is escape and rescue rather than air quality.

Then trenches. This is the one worth reading twice: Trenches are not considered confined spaces based on the risk of structural collapse alone, but will be confined spaces if they potentially contain concentrations of airborne contaminants that may cause impairment, loss of consciousness or asphyxiation.

So the deadliest thing about most trenches, collapse, is not what makes them a confined space. Trench collapse is governed by the excavation duties instead. A trench becomes a confined space when the air in it might hurt you, which is a different control set, a different permit and a different rescue plan.

Entry does not mean climbing in

The definition of entry is narrower than most site practice assumes: Entry into a confined space means a person’s head or upper body is in the confined space or within the boundary of the confined space.

Leaning through a hatch to look, or to reach a valve, is entry. If the space is a confined space, every duty that attaches to entry attaches to that lean, including the permit. This is the single most commonly breached line in the Code, because it does not feel like entering anything.

The permit, and the timing trap inside it

A confined space entry permit must be issued for each time work is to be carried out in a confined space, and each permit only applies to one confined space while allowing one or more workers into it. It is not a site-wide authorisation and it is not annual.

Now the part that catches out even careful operators. The Code states: A confined space entry permit is also required when a person enters a confined space to conduct the initial hazard identification or risk assessment.

You need the permit before the assessment that informs the permit. That is not circular in practice, it just means the first entry is itself permitted work, on the information available then, and the Code notes the permit may need to be revised after the risk assessment is completed. The failure mode it exists to stop is obvious once stated: the person who dies is very often the one who went in briefly, first, to have a look.

On records, permits are kept for at least two years after the work if a notifiable incident occurs in connection with it.

Signs, and why they are not the control

Before work starts, signs must be erected to prevent entry of persons not involved in the work, warning against entry by anyone not listed on the permit, placed at each entrance. They must stay up while the space is accessible, which the Code spells out as including preparation and pack-up, not only the work itself.

And then the sentence that tells you what the Code thinks of signage as a control: Signposting alone should not be relied on to prevent unauthorised entry to a potential confined space. It calls for security devices, locks and fixed barriers. A sign informs a person who is already choosing to comply; a lock stops one who is not.

Who is a competent person

The term does a lot of work in this Code, and its definition is broader than a ticket: A competent person is one who has acquired through training, qualification or experience the knowledge and skills to carry out the task. Experience counts, and a certificate on its own does not discharge the duty if the knowledge is not there.