I think that some of you have gone off on a tangent.
The OP wanted to know about derating cables running through spray foan insulation. Not derating cables when bundled.
The CEC has clear rules for derating cables when bundled.
As for derating when run through spray foam insulation, I have worked on houses where the walls were going to be spray foamed and I didn't worry about the derating because I never load my circuits up to the max. For example the CEC allows 12 receptacles per circuit, but I never put more than 10 on a circuit. So in effect I guess you could say that I automatically derate by 16%.
I don't believe that a rule exists in Canada at this time concerning running conductors through spray foam insulation.
I was hoping that mikesh would have contributed by now. It would be interesting to hear an inspectors opinion on this.
Of course if I'm wrong and the OP was concerned about derating when bundling, then just ignore this whole post.
