Expanding a one gang metal box into a two gang


Old 09-03-15, 03:18 PM
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Join Date: Oct 2005
Location: Florida
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Extending a one gang metal box into a two gang

I did something yesterday that I am not sure if it's to code.

1965 building, all EMTs and metal boxes. I have a one gang metal handy box with a single toggle switch, and I wanted to have a duplex receptacle and a switch there. I know there is a decora device where there is a switch and a single receptacle but I wanted a duplex, and besides, the box is tight and I try to avoid having to take out the old box and replace with a 2 gang box.

So this is what I did.

I put a 2 gang 1 device flat mud ring over the metal handy box.

I align the top and bottom screw holes in the middle to the handy box screw holes.

Then I got a weatherproof 1" metal extension ring made by RED DOT I believe.

It also has two screw holes in the middle at the top and bottom. I believe you could also use a wire mold extension ring.

Align the two screw holes on the 1 gang box, with the flat mud ring, then the weatherproof extension ring, secure with a pair of 1-1/4" screws.

What I end up with is another inch of room protruded from the finished wall, yet I was able to mount two devices on it, and with a standard cover plate it still look OK. If you need more depth for GFCI receptacles there are deeper wire mold extension rings.

This is OK right? The extended box, even though it is 2 gang, the back side of it is framed by the flat mud ring, so it is still metal all the way around on the inside. Do you see a problem with this?
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Old 09-04-15, 04:20 PM
Tolyn Ironhand's Avatar
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It sounds pretty hodgepodge and I don't think that flat mud ring was designed for that propose, and therefore a violation.

If it doesn't matter what it looks like I would have used this extension ring:

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Then you can install what ever mudring you want, or install an industrial plate.

Otherwise, if you want it to look nicer a two gang wiremold box with an open back could be used.

Last edited by Tolyn Ironhand; 09-04-15 at 04:53 PM.
Old 09-04-15, 04:53 PM
Join Date: Nov 2012
Location: USA
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That is certainly interesting,but parts are not used as intended,if that handy box is flush with the surface then you should have used a Wiremold extension box designed for the purpose,and even that won't give you a 2 gang out of a single handy box,seems the only correct solution is a combo SW/Rec
Device even though you want a duplex.
Old 09-04-15, 05:01 PM
PJmax's Avatar
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Wiremold makes almost any combination you can think of. They offer a deep two gang box with a single gang knockout back plate.

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