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Using a Wiremold metal starter box to extend an in-wall box #84158
03/12/03 03:32 PM
03/12/03 03:32 PM
SvenNYC  Offline OP
Joined: Aug 2002
Posts: 1,691
New York City
This Saturday I was replacing a two-pin outlet for a grounded outlet (the system is grounded - I checked with a circuit tester).

The duplex outlet had two conductors per screw (someone in the past had ran power from this middle-of-the-run receptacle to another outlet). In order to fix this, I "pigtailed" the wires so that only one wire would be wrapped around each screw:

OK, to explain my little ASCII art attempt

The continous top and bottom lines represent each wire that was previously wrapped to the scrw. The { is a splicing cap. The X is the screw.

Now....when I went to stick the device back in the box, I discovered that the shallow 4 x 4 box plus mudring was...well...full. This is a thin masonry wall in a housing project.

Having someone rip open the wall and replace the box with something much deeper would probably have been out of the question, so I used a metal starter box for Wiremold raceways - the ones with the open back to put over an existing in-wall device box.

This allowed room in the original box for the wires and the device was contained in the starter box.

Now...was this a proper solution or could this be a violation?

Picture this as putting in a raceway system and tapping off an existing box, but of course there's no raceway, it's only the box (with all knockouts closed).

I will have to do this again to another room where there are off-set open backed boxes that feed receptacles in adjacent rooms (the things are almost back to back, open in the rear so you can see the back of the receptacle in the adjoining room. Once again the lazy ass who tapped power from one room to the other did the two wires per terminal thing in a middle of the run outlet:

neutral------[||]----- existing wire (hot)

neutral------[||]----- existing wire (hot)
------ ----- new "tapping"

There is absolutely no more room in the box for the pigtails I'm going to use (and the splicing caps). It's already a tight squeeze in there with those receptacles. Ripping open the walls is not an option, that's for sure.

I hope I haven't confused you guys yet.

What would a REAL electrician do in this case?

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Re: Using a Wiremold metal starter box to extend an in-wall box #84159
03/12/03 03:55 PM
03/12/03 03:55 PM
HotLine1  Offline

Joined: Apr 2002
Posts: 6,917
Brick, NJ USA
What you are proosing, or did is a "fix" for your problem. Your method will "add additional cubic inches" of capacity for the existing conductors. And, as a last resort kind of thing, it's a lot better than trying to stuff everything back in the box.
You can check the CI volume of the existing box, and add the extension, then apply the NEC formula to determine if you have enough space. If not, then go to the next larger size extension box.

BTW, I don't know the "rules" in NYC, but here in NJ, YOU cannot legally do any electrical work in a multi-family dwelling without a license.

Do you mean you have four (4) hots, and four (4) neutrals that where on the receptacle screws???


[This message has been edited by HotLine1 (edited 03-12-2003).]

Re: Using a Wiremold metal starter box to extend an in-wall box #84160
03/12/03 04:14 PM
03/12/03 04:14 PM
SvenNYC  Offline OP
Joined: Aug 2002
Posts: 1,691
New York City

No, each receptacle screw had two hots and two neutrals on it respectively (2 hots on one screw, two neutrals on another screw).

Middle of the run receptacle (all four terminals used) with a "tap-off" or spur going to a socket in another room.

They simply added the new wire to the existing terminal screws!

This is a city owned building, see my post here: -- oh you did see it already. [Linked Image]

I was also replacing the combination light switch/GFCI receptacle in the bathroom and discovered they used BX cable into a box with a clamp designed for NM (at least they used a red-devil to protect the wires)!!! [Linked Image]

[This message has been edited by SvenNYC (edited 03-12-2003).]

Re: Using a Wiremold metal starter box to extend an in-wall box #84161
03/12/03 08:11 PM
03/12/03 08:11 PM
ccdave  Offline
Joined: Jan 2003
Posts: 59
culver city,calif. usa
could you possibly have a "hot" line and load under the screws? It seems that the wire mold extention boxes would be too large for the outlet opening and there fore loosing your fire rating.. mabey not-be careful


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