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

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

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.