I am a new homeowner and am relatively handy. I have worked in building maintenance at a hospital, but I am not entirely familiar with the electrical codes.

I was meaning to replace a faulty outdoor outlet but discovered that the metal box (no backing to it) that housed the outlet was attached to a plastic box in an exterior wall (transitioning from Romex). Additionally, this outlet then leads into a PVC conduit (possibly just PVC pipe) containing more Romex that ultimately goes a couple of inches underground traveling about six feet, leading to another outlet and floodlight in an inconvenient location.

I suspect that I am dealing with the work of the previous homeowner rather than an electrician. I have a few questions about this:

  1. Is the transition from Romex to a PVC conduit correct? I asked someone at Home Depot and was told it was correct. Common sense suggested that it would at least potentially allow water into the wall without some kind of flashing, adhesive, and / or silicone.

  2. Is it allowable to run Romex in PVC conduit or pipe? I know that you can’t do that in EMC but not sure if it’s also the case for PVC. Also, is there any difference between pvc pipe and pvc conduit?

  3. If I had to redo the conduit to the floodlight and outlet, would I need to use PVC conduit (or some weatherproof application) and would it need to be “underground” a couple of inches as opposed to just running it on the ground next the exterior wall?

  • 4
    Post a photo please. It's much easier to offer advice if we can see. Commented Jan 7 at 4:07
  • 2
    You cannot run NM-B (Romex) in wet environments. AFAIK, any outdoor conduit is considered a wet environment.
    – DoxyLover
    Commented Jan 7 at 5:03
  • The 'Romex' could be uf cable (usually gray), in which case it is okay if installed according to NEC 340. The metal box with no back is probably a box extension, which is okay provided it is suitable for wet locations and sealed properly. Review section 340, but the cable needs to be protected from damage, so put it in conduit and use weather-tight connectors and seal devices. If things get wet, the gfci, which should be in place, will trip.
    – RG Hughes
    Commented Jan 7 at 5:16

1 Answer 1


All exterior conduit is defined as a wet location, and NM/B (Romex® being one common brand) is not allowed in wet locations at all. The vast majority of exterior conduits live up to the definition.

PVC conduit is gray and (if not painted over) marked as conduit. PVC pipe is usually white, and marked with various pipe related things like service pressure and DWV or PW depending on the pipe. Pipe is not acceptable as conduit.

If the conduit runs along the wall it does not need to be buried, it can be attached to the wall. If it's buried, it needs to be a lot deeper (12" to top of conduit if GFCI protected and less than 20A, 18" otherwise) or protected by concrete. On the wall and below 8 feet in height, it should be schedule 80, not schedule 40 as it's considered "exposed to damage" in most jurisdictions.

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