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I am upgrading some circuits around the house and I found one that has me stumped. There is 12/2 UF-B running from my garage sub, under my deck and terminating at a PVC C-type conduit body across the deck. There it is spliced with romex, which is then run up 2 ft of 1/2" PVC conduit to a weatherproof receptacle box sitting above the deck and strapped against my house.

I know running romex both outside and through conduit isn't to code so I want to replace it with THWN that I have on hand. The question is, if I splice the THWN to the UF-B in the conduit body using wagos, will I be in violation of code? What is the "to code" way to make the splice? Is there a rain proof connector for UF-b entering PVC?

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    Romex in (interior) conduit is fine. It's a terrible idea in 99% of cases, which is why it's always advised against (harder to pull, fill is terrible.) You are correct that Romex in exterior conduit (wet location) is very forbidden.
    – Ecnerwal
    Sep 13 at 2:20
  • See also discussion here diychatroom.com/threads/…
    – Harper - Reinstate Monica
    Sep 13 at 17:49

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You need a gland bushing to connect to a threaded conduit body or to a pvc female adapter and short piece of pvc to plastic conduit body.

Your big issue is NEC 314.16 specifies you need to comply with box fill rules calculations, you will need to oversize the conduit body and use reducing bushings to fit conduit size used. You are best advised to use a junction box to accomplish the required cubic inches. Most boxes and conduit bodies are labelled with their cubic inch capacity.

Splicing in a weatherproof box does not require special wire connectors.

Edit: I realize the box fill calculator I linked to isn't very good, so to clarify for example each #12 conductor entering the condulet (or box) requires 2.25 in³, plus up to 4 ground wires count as 1. So you have 5 x 2.25, you need an 11.25 in³ enclosure. A Cantex brand 3/4" "C" has a capacity of only 6.8 in³, so you would need to use a 1" with a capacity of 11.8 in³.

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  • The calculation above only represents conditions likely to exist in the scenario as I understand it, boxes with devices and other internal components would add capacity.
    – NoSparksPlease
    Sep 13 at 15:26
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Wago apprently makes a wet-location accessory for leverlocks. So if those are your preferred wire splicing technique, you're in luck.

There are also wet location wirenuts available.

The sealed entry (cable gland) for UF-B cable would usually be to a threaded box connection, which you get by putting a PVC to threaded adapter (gray, from the electrical aisle, not white from the plumbing aisle) on your PVC conduit body.

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    @FreeMan This is perfectly fine. From the Wago web page For example, in low-voltage applications (e.g., 230 V) I don't know the exact specifications, but it is something like extra low voltage up to 50V (so it covers 12V, 24V, 48V) and low voltage is likely up to either 300V (just above the typical 208/220/230/240/250/277) or possibly 600V (maximum rating on insulation on lots of stuff and which also includes 480V).
    – manassehkatz-Moving 2 Codidact
    Sep 13 at 14:21
  • @FreeMan The Wago website continues "For example, in low-voltage applications (e.g., 230 V), the Gelboxes are used in junction boxes together with splicing connectors. This is the only way to ensure double cable insulation to protect against electric shock, since only the conductors are encapsulated in the WAGO Gelbox" Sounds like something more than just these gelboxes are needed.
    – Armand
    Sep 13 at 14:25
  • Fair points, @all - I read the first blurb, applied my North American bias, and jumped to conclusions. mea culpa
    – FreeMan
    Sep 13 at 14:46

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