S-2.1, r. 14 - Regulation respecting occupational health and safety in mines

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142.1. A stationary natural gas or propane heating system may not be used to heat a building covering an opening to the surface of an underground mine, except where the following conditions are satisfied:
(1)  the heating unit is certified by a recognized body such as the Canadian Standards Association (CSA), the Canadian Gas Association (CGA), the Canadian Underwriters’ Association (CUA) or a similar body;
(2)  the entire installation complies with the Regulation respecting gas and public safety (chapter D-10, r. 4), as well as with CAN/CGA-B149.1-M91 Natural Gas Installation Code, where natural gas is used as fuel, or CAN/CGA-B149.2-M91 Propane Installation Code, where propane is used as fuel;
(3)  where the fuel is propane, a combustible gas detector is installed to ensure the cut-off of fuel to the heating apparatus if propane gas should accumulate inside the building;
(4)  the heating apparatus is installed in such a manner that the distance between it and any explosive is never less than 4 m (13.1 ft).
O.C. 782-97, s. 20.