Appendix B Rule 12-012

Wooden planks, when buried in the ground, should be treated with a solution of pentachlorophenol or
other suitable material as recommended by a manufacturer of wood preservatives. The use of creosote
as a wood preservative in such installations is not recommended because it is known to damage rubber
and thermoplastic insulations and acts as a catalyst in the corrosion of lead.

Rule 12-012 4)
The maximum size of sand is based on standard sieve sizes detailed in ASTM D2487.

Rule 12-012 12)
The intent of this Subrule is to avoid damage to the installation during movement of the building,
raceway, or cable.

Δ Rule 12-022
For the application of this Rule, the surface area below the actual metal roof pan and an attic space are not considered part of the roof decking system.

Where roof decking systems are mechanically fastened using screws or other penetrating metal fasteners, exposed cables and raceways should not be attached to the roof metal pan system until
substantial completion of the roof decking system’s mechanical fastening.

Δ Figure B12-1
Cables or raceways installed in roof decking systems

Cables or raceways installed in roof decking systems

It is not the intent of this Rule to require the relocation of existing cables or raceways when a roof decking system is repaired or replaced.

For additional information on roofing systems, refer to the National Building Code of Canada and
CSA A123.21.

Source: Appendix B Rule 12-012, CSA C22.1:21, Canadian Electrical Code, Part 1 (25th Edition), Safety Standard for Electrical Installations. © 2021 Canadian Standards Association. Please visit