I’m upgrading to a 200 amp panel and I’m using a surface mount on my stucco exterior. I tried reaching my inspector but due to the pandemic he’s been unavailable.

I will be applying urethane caulk around the top and sides of the box.

What is proper practice for running (nm-b) cable from the inside of the wall into the knockouts of my exterior main panel?

My electrician says to the caulk is enough, I just want a second opinion.

new panel

  • 1
    If this is surface mounted to the outside of your house, you cannot use romex (NM-B) cable. This is considered a wet location. Aug 3, 2021 at 17:28
  • If you wish to seek the blessing of a state official you will probably get better response from the building inspector rather than the electrical inspector. Aug 3, 2021 at 19:25
  • @NoSparksPlease I just want to know what would other electrician do in this situation and further educate myself Aug 3, 2021 at 19:42
  • @user3630509 correct, as soon as it exits the wall, you're outside/wet location. See for example diy.stackexchange.com/a/108301/65622 Aug 3, 2021 at 21:48
  • NEC 334.12(B) Type NM cables shall not be used under the following conditions or in the following locations (4) In wet or damp locations, Article 100 Definitions, Location, Damp. Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture. Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold storage warehouses. Aug 3, 2021 at 23:30


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