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Can anyone advise if running a cable through a outside wall, one is allowed to terminate that cable immediately on that outside wall in the form of a NEMA 14-50 outlet? I live in Maryland, USA, if that is helpful.

Would be extra helpful if a link to an online copy of section of the electrical code that stipulated the requirements in the above regard could be provided in an answer.

  • What kind of cable are we talking about here? And is the box for the outlet flush-mounted into the wall, or surface-mounted to the wall? – ThreePhaseEel Dec 27 '18 at 23:25
  • @ThreePhaseEel - Didn't realize wire size mattered to the question. Need full amperage 14-50 is able to carry, so cable size in the order of 8/3. Also, surface mounted (unless necessary, have no desire to drill out more of the concrete than necessary). – user66001 Dec 28 '18 at 6:53
  • Size isn't the issue, the type of cable though is -- can we presume this is ordinary NM cable, or is it something else instead? – ThreePhaseEel Dec 28 '18 at 12:42
  • @ThreePhaseEel - Ah, sorry, yes, NM cable. – user66001 Dec 28 '18 at 15:13
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It's not prohibited, just not the wisest thing in the world

While entering a NM cable into a box mounted on the outside of a wall via the back of the box is permitted by Code, it's not a particularly wise move since the paper filler in NM can wick water that gets into the box up the cable, causing a difficult-to-troubleshoot issue down the road. Using a length of UF of the same gauge from the last indoor box on the circuit into the outdoor box avoids this problem in a relatively inexpensive way.

  • Thanks for the answer. Might you be able to point me to the NEC code online that I could read more about the rules in regards to wall boxes, cable requirements, etc? – user66001 Dec 28 '18 at 22:45
  • This particular answer has to do with the absence of wording in Code -- the inside of a wet-location-rated box is not considered a wet location (NEC 314.15 would say so otherwise). – ThreePhaseEel Dec 28 '18 at 23:41
  • Thanks. Might at least section 314.5 be available to read in it's entirity online? – user66001 Dec 29 '18 at 10:24

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