I am updating the electrical systems in my old, detached, unfinished garage. The previous owner cut holes in the siding to put in old work PVC boxes for flush mounted outlets on the exterior on the garage, fed by Romex/NM wire inside, about 2 feet from the floor. I'm trying to bring this up to code for inspection by replacing the NM wire with THHN in EMT to satisfy 334.15(B).

Is there anything available that would let me flush mount an outlet in a metal box or EMT-compatible box in the same manner?

1 Answer 1


You need to use weatherproof boxes if this is facing the exterior of the garage, which are typically plastic. Regular old metal boxes are for interior use with exposed walls. Select the box you need, then find the fittings recommended for connecting EMT to it.

  • Note that plastic weatherproof boxes do not mate well to EMT due to the threadless hub fittings they use (they're designed for PVC conduit instead). One can use a metal weatherproof box (Bell box), but even those require a special transition fitting (Bridgeport 25x-RTNPT or equivalent, or a composite transition made using a standard EMT compression-to-RMC coupling and a short RMC nipple) instead of a normal compression connector... Sep 1, 2023 at 1:59
  • Agreed but you have to start at the most egregious violation and work backwards, which is dependent on what else us installed in the garage. Worst case scenario run pvc from the weatherproof box back to an interior metal box, same as you would on the side of the house.
    – Frank
    Sep 1, 2023 at 2:24
  • Yeah, if you're stuck with a plastic weatherproof box, you can use a short stub of Sch 80 to a female adapter to get to some sort of threading you can then attach an EMT connector to (threading straight threads into PVC female adapters indoors isn't a big deal because you're not relying on the threads for grounding or watertightness, just mechanical stability) Sep 1, 2023 at 3:15

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