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Wednesday, February 1, 2017
Question:
I have had a long debate about whether or not you can run Romex (NM) from the inside of a building through the exterior wall right into the back of a weatherproof box. Article 314.15 Damp, Wet or Hazardous Locations Boxes, conduit bodies and fittings in damp or wet locations, must be placed or equipped so as to prevent moisture from entering or accumulating within the box. So if the box is installed to code and moisture is prevented from entering or accumulating within the box would the inside of the box be considered a wet/damp location? If you run NM cable from the interior of a building directly into the back of the box and the box is installed to code the NM cable never enters a damp/wet location. There will be no moisture for the paper inside the NM to wick. Please put an end to this discussion and include code articles to back up any answers. Thank you very much for your time.
Michael Casagranda
A
Answer:
Hey Michael thanks for your question. If everything is installed correctly then yes that is the theory. Take a look at 300.5(B) which states that the interior of enclosures and raceways installed underground are considered to be a wet location. I know your example is not underground. Notice that in 300.9 for above grade installations only raceways are included, the word "enclosure" is not used. Make sure your local AHJ agrees with this interpretation.