[thedusen]

The short TL;DR version:

1. Is it a violation of NEC to put metal boxes on top of uncapped in-wall plastic electrical boxes (basically hiding them) if all the wiring in the in-wall plastic boxes is not only capped but also not connected to any live circuit?

2. If it's okay, any recommendations/regulations on how to secure a box on top of a hole? I saw mention of fitting a piece of wood inside the old, unused box. Seems cumbersome.

The details:

I have a detached 330 sq ft building I'm turning into my office and art/recording studio. The big project is running a subpanel out there and running new wire.

But because it will be used as a recording studio, I can't rely on any of the existing wiring, as there are "best practices" for wiring a recording studio to minimize noise from ground loops, etc (for example, it's recommended that all receptacles have independent grounds running back to the panel. 4 receptacles, 4 ground wires terminated on the bus)

So I've decided to wire all new receptacles, switches, and sockets through exposed metal conduit/boxes... and I'm gonna have fun with their design because... why not?

Is there anything in NEC stopping me from doing that? If so, is there a solution? If not, any tips/tricks/recommendations on how to properly/safely secure a metal box on top of an existing hole?

If it makes a difference, my plan is for almost all the 1 gang boxes to be replaced with 2 gangs minimum, so there are no gaps around the preexisting holes and for the extra wire I might use.

THANK YOU!

Mitch

 

[J. V.]

If I was doing it I would cap the wires (wirenuts) fold them back neatly and put blank plastic or metal plates over the existing receptacle and switch boxes.
Then run all the conduit and set all the boxes you want.

You never know what an inspector might say. I know of no code violation per say.
But it is a code violation to bury or cover any junction, receptacle or switch box as they must remain accessible.
Be they dead or alive, might be the issue?

 

[surferdude2]

Dead wires will have to be nutted off at the outlet and removed from the panel to satisfy most inspectors.

As for the box mounting, you could go with 2-gang boxes that would span the opening and make for easy mounting with screws and possibly anchors. You can get single gang plates for 2-gang boxes or else mount two devices. You may also want to use an isolated ground conductor that runs all the way back to the ground electrode conductor for the service and use isolated ground receptacles. The EMT can be electrically noisy.

Edit, Rereading your post... I see you are already going with an independent ground... just don't tie it to the any box or panel anywhere but where the building ground electrode conductor lands in the main panel.

 

[brric]

 

[surferdude2]

View attachment 594501

Good thought, but I doubt the inspector will buy it since the dead wires aren't plated off and isolated from the live wires. It'd be a gamble I wouldn't want to take since getting an inspector down on an issue will mean you have to come up with a UL approved fix and that wouldn't be easy using that box. I'd rather he couldn't see those old boxes at all.

 

[Oldmaster]

If the wiring in the box is disconnected from all sources and no longer used it can be covered.

 

[Jim Port]

Agree with Oldmaster. No need for wiring to be accessible after being abandoned properly.

 

[thedusen]

Thanks all. Had an epiphany on how to search for the code after the feedback. Looks like NEC 2017 has made a deal out of abandoned wires. Basically, any wires that are abandoned should be removed as much as possible (i.e. not meaning you start tearing up the walls). So I'll be doing that.

But it still leaves the whole thing of adding surface mount boxes on top.

As for the box mounting, you could go with 2-gang boxes that would span the opening and make for easy mounting with screws and possibly anchors. You can get single gang plates for 2-gang boxes or else mount two devices.

I think this should work fine... except for where there are already 2-gang plastic boxes.

Any ingenious way to stuff an old box so I can securely mount a new one :vs_laugh:

Thanks all