Canada Occupational Health and Safety Regulations

11.1 (1) Unless a qualified person has determined that the work can be performed safely, the employer must ensure that hot work is not performed in a hazardous confined space that contains

• (a) an explosive or flammable hazardous substance in a concentration in excess of 10% of its lower explosive limit; or

• (b) oxygen in a concentration in excess of 23%.

(2) If hot work is to be performed in a hazardous confined space that contains concentrations of flammable or explosive materials in excess of the concentrations set out in paragraph (1)(a) or (b),

• (a) a qualified person must patrol the area surrounding the hazardous confined space and maintain a fire-protection watch in that area until the fire hazard has passed; and

• (b) the employer must ensure that the emergency equipment specified under paragraph 11.03(2)(c) is provided in the area referred to in paragraph (a).

(3) If an airborne hazardous substance can be produced by hot work in a hazardous confined space, the employer must ensure that no person enters or occupies that hazardous confined space unless

• (a) the requirements of section 11.11 are met; or

• (b) that person uses respiratory protection equipment that meets the requirements of sections 12.04, 12.05 and 12.13.