Running romex into a surface mount box

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Old 11-17-19, 03:06 PM
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Running romex into a surface mount box

I'm going to run some romex from inside a wall into an attached garage, and from there I'll run surface mount EMT conduit (will splice the romex to THHN wire for the conduit run). What is the NEC code compliant way to bring the romex through the drywall and into a surface mount box like this:


Do I simply punch out one of the rear knockouts and drill a hole through the drywall and pull the romex in? I'm guessing there is some kind of connector designed for this that has one end that sticks into the drywall and the other end sticks into the box's knockout and secures itself to the box?
 
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11-18-19, 02:34 AM
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Do yourself a favor and use a 4 square box. The box shown is too small.
 
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Old 11-17-19, 11:47 PM
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If it's a short conduit run.... you can pull the nm-b in thru it as a sleeve.

The best thing to use on the back of a box is a snap in grommet.
It doesn't require the hole in the sheetrock to be too large.

Arlington NM 94 grommet
 
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Old 11-18-19, 02:34 AM
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Do yourself a favor and use a 4 square box. The box shown is too small.
 
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Old 11-18-19, 08:23 AM
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With that snap-in grommet, I guess the idea is make the hole in the sheetrock just large enough to fit the outside diameter of the grommet, so that the electrical box sits flush against the sheetrock?
 
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Old 11-18-19, 09:49 AM
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Any metal box you use must be attached to the NM grounding conductor.
 
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Old 11-18-19, 04:03 PM
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@PJmax - yeah, I might end up with multiple NM-B cables in some sections in the garage, and while I could run NM-B in EMT conduit, the code limits on conduit fill would mean using large diameter conduit. If I go with THHN, I can use 1/2" EMT.

@pcboss - good call. I ended up getting a 4-11/16" square x 2" deep box. Might as well throw a GFCI outlet in there while I'm putting a box up on the wall. Would be in a good spot in my garage to leave a tool battery charger.

@telecom guy - yep.
 
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