I have 1 inch EMT conduit in the garage on the wall, passing (4 wires) 4AWG THHN wire through conduit body inside the cavity of the wall into the main panel, is this allowed?


1 Answer 1



Conduit used as a wiring method suitable for housing THHN, must be entirely end-to-end the entire run. There can't be gaps (especially if the metal conduit is carrying the ground instead of a wire!)

Conduit must be built fully complete, empty, before any wires are pulled in. That means the conduit must be built to be pullable, with all corners either being broad curves ("sweeps") or boxes or conduit bodies with a removable lid to aid in pulling.

Conduit must be serviceable so the wires can be accessed to pull them out for inspection or upgrade.

All this means all box and conduit body lids must remain accessible forever without needing tools or damaging finish surfaces to access them.

So your idea of burying a conduit body in the wall is a nonstarter. You must either use a sweep, put a junction box there and install a mud ring and blank cover there... or make it a little cabinet door with a latch (if that's a fire rated wall, you may have to box in the stud bay with drywall or something to retain the fire rating).

If you haven't bought the #4 wire yet, don't and let's talk. We often see certain errors: running a #4 ground when you don't need to, using copper when aluminum really is better for large feeders, and thinking #4Cu is good for 100A when it's only good to 85A. Most people use the popular #2 aluminum for a 90A feeder. The subpanel can be any size >= the feeder.

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