View Full Version : Wall insulation around cabling - OK?

06-16-2008, 10:55 AM
For my bathroom reno, I am wondering if it would be acceptable (i.e. safe) to place insulation (fibreglass-type batts) in contact with the newly installed NM cables leading to/from the switches and fixtures? I am thinking of possible heat issues (sorry if this is a n00b concern, I really don't know).

The cables are typically 14/2, and there is one 14/3.

If not, is there a minimum safe distance they should be kept free?

Bob NH
06-16-2008, 11:49 AM
There is no problem placing insulation around NM.

Modern NM has 90 C isulation at which 14, 12, and 10 are rated at 25, 30, and 40 Amps; and those ratings are based on 3 current-carrying conductors. However, the NEC limits the use of 14, 12, and 10 to 15, 20, and 30 Amps. The heating for the permitted amps is 36%, 44%, and 56% of the 90 C ratings.

The large margin of safety means the insulation won't be a problem.

06-16-2008, 12:15 PM
Thanks for the detailed answer, much appreciated (especially the conclusion, hehe...:))