Extra large wall opening for outlet box

fw2007 · 10-02-2007, 07:53 PM

Hi;
I am rewiring the outlets in my kitchen. I had to remove the boxes on two of the outlets on the counter because the boxes were so far recessed behind the Formica wall that there was a large gap with combustible material surrounding it!

After I pulled the boxes out, I have over-sized cutouts in the Formica for the boxes. That is what the contractor who installed the counter did. Then he used very long screws for the receptacles. Ground was intermittent at best!

When I install the new boxes, I am concerned that the mounting ears will not be outside the cutout, so I won't have anything to hold the box in place.
The old boxes were mounted (if you can call it that) to the original wall, which is approx 3" behind the Formica wall of the counter.

Any ideas as to what I should do about mounting the new (metallic) boxes.
Note: I must use metallic boxes because some of the cable is BX.

Thanks

FW

Stubbie · 10-02-2007, 09:33 PM

You will need extension rings to mount on the face of the boxes to bring them out to the finished surface. Your biggest problem is remounting the boxes if the face of the stud is 3 " back of the finished surface. I'm having some difficulty visualizing how that is....are they mounted thru the back splash of the countertop?

Stubbie

fw2007 · 10-03-2007, 12:34 AM

The boxes were mounted to the plaster wall, which is behind the finished surface of the wall.
The boxes were never mounted to the studs. They were basically thrown into holes cut into the plaster wall and "secured" in whatever way was convenient.
What I found was one screw through one of the plaster ears, and a piece of bare copper wire looped through two of the other holes, and through something in the wall. There is some kind of steel mesh in the wall. Probably the ancient plaster wall had this steel mesh to strengthen it.

When the counter was installed, the finish was installed over the old plaster somehow. The distance between the old plaster wall and the finished surface is significant; Maybe not 3" as I claim, but enough to cause a problem with the box.

I was planning to mount the new boxes directly to the finished surface, which is about 3/8" thick.
If the stud was available, I would secure the boxes to them, but I have yet to see a stud.

On at least the cutout pictured, I believe the box will be smaller, and the mounting holes in the plaster ears will fall below the finished surface, causing the screws to hang freely rather than screw into the finished wall. So I need something to more or less bring the finished wall surface back to the edge of the box so that the screws can secure the box.
Perhaps some sort of flange plate that would go around the box and have holes for securing the box through the holes in the plaster ears.

Maybe what I can do is open up the cutout (to the correct height on each side of the current cutout) to fit a two-gang box and install two duplex in each.
I would end up with a cutout that is a bit high in the center, but at least I would have two of the four screws on each side of the double box into the finished wall.
Having double duplex in each location would be nice.
Each of these will have it's own 20A breaker and a GFCI outlet.

The alternate plan - double gang boxes:

Thanks

FW

frenchelectrican · 10-03-2007, 01:44 AM

Let me reply this one

i dont know if you ever checked the old work box the plastic verison useally are larger than steel oldwork box sizewise ??

how deep the wall if you stated then i miss it but if not please post it here so i can able help you get the right size box for ya other wise the other option it will be little pain in the you know what i mean.

bear with me a min one way you say want to put in two gang box but here is the trick you can use the 4X4 X 1 1/2 box metal box with proper clamps on it and what you can do is breach tthe hole little larger than the box itself just get it in nice and what you do is mount the box drectaly on the brick wall and get the mud ring they will come in few diffrent depths like 1/4 , 1/2 , 5/8 ,3/4 ,1 and i think few more thicker the mud ring can come in one gang size or two gang size you may have to add a pigtail with this because the depth of the box IMO it willbe easiser after you put in the box and before you get the mud ring installed and Make sure you get the ground wire hookup good and haveit bonded on the metal box too with green screw on it

after the box is installed per instruction you can back fill with drywall mud to level it out and it should work this way

Merci, Marc

fw2007 · 10-03-2007, 08:44 PM

Well, the job turned out OK.
I used a plastic box on the suggestion by frenchelectrican. It was larger, and worked fine in the hole after I trimmed the edges of the cutout with a keyhole saw.
The box also has those flip-up and pull-in flaps that pull the box against the inside of the wall, and I probably could have done without the plaster ears anyway, but I installed the four screws.

One thing I don't like about these plastic boxes is that they don't secure the Romex cable as well as the steel boxes do when you use the standard Romex clamp (thread into a knockout).
Is there a secret to get the Romex to really stay in the box in case it's pulled on?
My cable runs about 4' from the basement joists up the wall, unsupported to the box in the kitchen. I suppose that the plastic boxes are best when used in new work, where the cable is secured to the stud near the box.
Anyway, I'm not going to complain. It seems fine. My cable is well supported downstairs, and I hardly think it will have the chance to be pulled out of the box.

For my second outlet, I am using a steel box because I have one BX and one Romex coming into it.
I don't expect any problem here, since the cutout is a bit smaller.

FW