This section provides a collection of definitions for confined space in the workplace.  Before learning about the requirements and conditions for entering confined spaces, there must be a high level of understanding with regard to the terms that may be used and their respective definitions.

Acceptable Atmospheric Levels

The atmospheric concentration of any explosive or flammable gas or vapour is less than:

• 25% of its lower explosive limit, if paragraph 1 of subsection 119.18 (4) applies.
• 10% of its lower explosive limit, if paragraph 2 of subsection 119.18 (4) applies.
• 5% of its lower explosive limit, if paragraph 3 of subsection 119.18 (4) applies.
• The oxygen content of the atmosphere is at least 19.5% but not more than 23% by volume. 
• The exposure to atmospheric contaminants does not exceed any applicable level set out in a regulation made under the Act and listed in Table 1.

Assessment

• Means an assessment of hazards with respect to one or more confined spaces in a workplace. 

Atmospheric Hazards

• The accumulation of flammable, combustible or explosive agents.
• An oxygen content in the atmosphere that is less than 19.5% or more than 23% by volume.
• The accumulation of atmospheric contaminants, including gases, vapours, fumes, dusts or mists, that could:
  • Result in acute health effects that pose an immediate threat to life.
  •  Interfere with a person’s ability to escape unaided from a confined space.

Cold Work

•  Means work that is not capable of producing a source of ignition.

Confined Space

• Means a fully or partially enclosed space:
  • That is not both designed and constructed for continuous human occupancy.
  • In which atmospheric hazards may occur because of the enclosed space’s construction, location or contents or because of work that is done in it. 

Emergency Work

• Means work performed in connection with an unforeseen event that involves an imminent danger to the life, health or safety of any person.

Hot Work

• Means work that is capable of producing a source of ignition.

Lead Employer

• Means an employer that contracts for the services of one or more other employers or independent contractors in relation to one or more confined spaces that are located:
  • In the lead employer’s own workplace.
  • In another employer’s workplace.

Confined Space Plan

• Means a plan for one or more confined spaces in a workplace.

Confined Space Program

• Means a program for one or more confined spaces in a workplace.

Purging

• Means displacing contaminants from a confined space.

Related Work

• Means work that is performed near a confined space in direct support of work inside the confined space.