Background: I am adding an equipment grounding wire (bare 10 gauge copper) from my electrical panel (in-wall mounted with access door to outside only) outside along about 10 feet of painted exterior aluminum siding to an external outlet in a weatherproof enclosure with 1/2 inch knockouts availabe. Pre-existing hot and neutral wires for outlet are coming into the outlet box from behind, through the wall, but I currently have no access to either the wall interior or the indoor part of the wall. EGC will be run in 3/8 aluminum flex conduit to outlet enclosure, with the flex running on the exterior siding surface, supported by clips.

Question: What connector to use for the 3/8 flex at the outlet enclosure? I have standard set-screw 3/8AC-to-1/2knockout threaded/lockring connectors, but it says those are for dry location use. My enclosure is on a wall exposed to rain, but the flex contains only bare copper ground, not energized conductors. I will be using a knockout on the bottom of the enclosure.

  • 1
    If you're going to use a conduit outdoors, it needs to be outdoor rated conduit even if the application is trivial. I'm not sure the ground wire needs protection. Jun 14, 2022 at 19:59
  • The other option is just to run the bare copper ground wire attached to the siding with clips. I was thinking at least putting it in aluminum (RWA) flex conduit would provide protection against mechanical disturbance. I would not worry about the copper wire getting wet, but wanted to make sure I didn't introduce excess moisture into the outlet enclosure. In any case, the new outlet is Weather Resistant rated.
    – Armand
    Jun 15, 2022 at 0:25

1 Answer 1


AC type cable is not listed for wet locations but MC may be (the stuff I purchase is it has a nylon coating).

However you need a wet location connector, the ones I use I think are called. MC “deck” connectors great for use in pool sheds and to boxes around the house outside surface mounted in wet locations.

If your “flex” is not coated it is not listed for a wet location but a damp location because moisture will enter the flex with no coating or sleeve. How do you tell if it is bright metal damp not wet location is the normal listing.

  • OK, "deck" seems to be the key word. I have seen that plastic coated flex. Appreciate your suggestions!
    – Armand
    Jun 15, 2022 at 0:23
  • @armand it is not a suggestion it is code , another contributor thinks a ground wire is the same and one of his many minions upvoted that ??? Answer , ,, sorry tired of all the internet only people on this DIY site upvoting each other , time to take another break
    – Ed Beal
    Jun 15, 2022 at 1:00
  • By "suggestions" I guess I really meant "information about what satisfies the code" :) I am certainly a beginner-ish DIYer on electrical, and have learned so much practical info here, so I do appreciate all the useful posts.
    – Armand
    Jun 15, 2022 at 2:37
  • Armand my entire answer points to code requirements using words like listed but if you would like type AC cable is in 320 of the NEC and 330 MC is in 330. Both are short but if you are in a wet location as your question suggests the “flex” must be listed for a wet location along with the connectors.
    – Ed Beal
    Jun 20, 2022 at 19:28

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