Three tests, and all three have to be read together: enclosed or partially enclosed, not designed for continuous occupancy, restricted entry or exit. A pit two metres across passes all three. So do a tank, a silo, a sewer chamber, a crawl space, the inside of a machine housing, and the trailer of a tanker. Nothing in the definition mentions size, and the space does not have to be hazardous today — it has to be capable of becoming so.
What it means in practice
- Entry is by written permit, issued after a hazard assessment by a competent person, valid for that entry, and closed out when the work is done.
- Atmospheric testing comes before entry and continues during it: oxygen first, then flammables, then toxics. Ventilation is a control, never a substitute for testing.
- An attendant stays outside, in continuous communication, with the means to summon rescue and without entering. That last clause is the one written in blood: a large share of confined-space fatalities are would-be rescuers.
- Rescue is arranged in advance, and calling 911 is not an arrangement unless the responding service has confirmed the capability and the response time.
- Entry counts as entry when any part of the body breaks the plane of the opening — reaching in to grab something is an entry.
What it is not
It is not a permit-required space only when something has gone wrong. The classification is done on the space’s potential, before anybody works there, and it is recorded.
It is not solved by a gas detector. A detector without a procedure, a trained entrant, an attendant and a rescue plan simply documents the atmosphere at the moment somebody died.
And it is not defined identically across Canada. Ontario and British Columbia word the tests differently, some jurisdictions add a “restricted space” category below the confined-space threshold, and the federal Code has its own regime. A corporate confined-space list built to one province’s definition will be wrong in another.