Canada Occupational Health and Safety Regulations

11.9 (1) Unless a qualified person has determined that the work can be performed safely, hot work shall not be performed in a confined space that contains

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

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

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

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

• (b) fire extinguishers specified as emergency equipment pursuant to paragraph 11.3(d) shall be provided in the area referred to in paragraph (a).

(3) Where an airborne hazardous substance may be produced by hot work in a confined space, no person shall enter or occupy the confined space unless

• (a) section 11.10 is complied with; or

• (b) the person uses a respiratory protective device that meets the requirements of sections 12.2, 12.3 and 12.7.