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Routing wires through masonry wall

Posted by joelbuckley (My Page) on
Mon, Mar 31, 08 at 16:39

Is there a code-compliant way to feed wiring through a masonry wall directly into the back of a surface-mount box, e.g. for a receptacle? The wall in question is stone, and it used to be an exterior wall, but it now separates the house from a sunroom, so I'd say this is a dry location.

I know I could come out of the wall with 1/2" EMT, then elbow into the side of the box. Just wondering if there's a better/easier way. I'd like to minimize the diameter of the hole I have to drill. What about using 3/8" aluminum flex attached to a knockout on the back of the box with one of those connectors that threads into the conduit spiral? Does flex provide enough protection?


Follow-Up Postings:

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RE: Routing wires through masonry wall

You can just run NM directly into the back of the handy box using a regular box connector (4040) or a locknut connector. If there is any chance of physical abrasion of the NM then just use a short run of PVC conduit through the wall. You can always glue a male threaded adapter to the PVC and where it enters the box use a lock ring to secure the PVC.


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RE: Routing wires through masonry wall

Thanks, bigbird. If the conduit is just to protect against physical abrasion, then THHN in flex (or MC cable) would be ok too, don't you think? All else being equal, I'd use a PVC sleeve like you suggest, but I think the flex will go through a smaller hole than any PVC conduit will go through. That stone is tough stuff.

There won't be any significant abrasion, regardless. I'm probably over-thinking this.


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RE: Routing wires through masonry wall

I'd ha' pushed a short length of UF through the wall, but can see nothing wrong with these other applications.


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