Wall insulation around cabling - OK?

Discussion in 'Electrical Forum discussion & Blog' started by Fistor, Jun 16, 2008.

  1. Fistor

    Fistor Geotechnical Engineer

    Messages:
    48
    Location:
    Vancouver, BC
    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?
  2. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    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.
  3. Fistor

    Fistor Geotechnical Engineer

    Messages:
    48
    Location:
    Vancouver, BC
    Thanks for the detailed answer, much appreciated (especially the conclusion, hehe...:))
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