Metal Drain Pipe very close to proposed outlet. Anything to be aware of?

[vyacheslav]

Greetings,

I am adding a switch and an outlet to a kitchen wall where there is currently none. After cutting the hole in the wall for the outlet box I noticed a drain pipe for the upstairs bathroom shower and sink. It is a drain pipe, it is not supplying water anywhere.

I'll obviously have to cut the outlet box so it's shallower (no big deal, I have done this in tight spots before) and there is room for the outlet (GFCI) to clear the pipe but just barely. Is it ok to have a metal pipe that close to the back of an outlet? I'll be using standard Romex wire. Should I insulate the pipe or wire with tape or anything?

Thanks for your help!

V

 

[Snoonyb]

So, rather than raising the box, you choose instead, to remove the design flame spread rating, for aesthetics?

 

[vyacheslav]

So, rather than raising the box, you choose instead, to remove the design flame spread rating, for aesthetics?

I'm not sure what you mean? There was nothing on that wall prior to this (no wiring or switches existed) There was nothing on the pipe or inside the wall other than the standard, first generation drywall (house built in 1950). I didn't remove anything other than the wall piece itself and it looked like all the other wall pieces I have removed from different areas of the house. I didn't remove any of the concrete or any insulation of any kind. What you see inside the wall in the photo is exactly how it was before I cut the hole. Only the 1st generation drywall has been removed; I did nothing else. I use a small, Stanley drywall knife by hand; there is no way that thing is cutting through any concrete. The box is to the right of and just below a window. I chose that specific location for the box based on switches and outlets on the opposite side of the window so things would look even (so the appearance would be "mirror images" of each other when looking at the window). I obviously didn't know what was behind the wall until I cut out the hole. I am always careful when I cut the hole. I ALWAYS assume something is behind it that I don't want damaged.

 

[slownsteady]

The whole point of the box is to protect the outlet. And also to contain any sparks/arcing/etc. that can occur with any electrical wiring. If you "cut the outlet box" what kind of protection does it serve? Are you suggesting that you leave the back of the box open?
Add to that a location below a window, which over time may develop a leak. I think you are asking for trouble with this scenario.

Maybe I am reading the orig. post wrong...hoping that I am.

 

[vyacheslav]

I have had to cut some plastic boxes narrower in certain instances when there was no room in the wall, and yes, that leaves the back of the box open. In these cases, the box is basically just used for mounting the outlets. In each of these cases however, I am using a GFCI outlet and the what's directly behind the outlet box/outlet is a brick wall-no drywall or insulation, just brick and mortar, just as if you were looking at it from the outside.

Most of the time it is not a problem but like I said, I have done this on two other instances. For this particular drain pipe box, I will also be using a GFCI and I plan on using electrical tape or something flame retardant around the pipe, unless there is an overwhelming feeling that this is a bad idea. FYI, it is to the right (about 5") and slightly below the windowsill, so it's far enough away from the window that any potential leaks shouldn't be a problem. The window is also brand new (less than a year old).

Thoughts?

 

[slownsteady]

I wouldn't do it.

You will be leaving a "ticking time bomb" in the wall. The fact that the other two instances have not caused trouble yet is merely a matter of luck. I would not want that potential problem in my home and I would not want to leave it there for the next occupant. There is no way that this would pass inspection.

 

[afjes_2016]

"Compromising the integrity of the box" - This is what an inspector would say. Even putting a screw through the wall of a plastic box to anchor it to a stud for example is the same thing. Boxes are designed for safety and approved for the same. Anything you do that is other than the actual design of the box compromises the safety factor.

It would be much better to patch the hole you cut and move the boxes to either side away from the pipes so you can use the boxes as designed.

Will anyone know you cut the back of the box out; probably not until one day there may be a fault in that receptacle/outlet and it sparks and the sparks fall and into dust etc behind the wall and starts a fire.

You can put all the tape you want on it but you are still causing a safety issue.

 

[Snoonyb]

Plastic boxes, in general, unaltered, are assumed to have a flame spread rating of 2 hours or less, "plastic boxes, also on single gang box? If you are discussing fire classification, most of Carlon's blue nonmetallic outlet boxes, with the exception of old work boxes, are fire classified for two-hour fire rated walls or less."

When you alter those boxes, by removing the back, you've removed that fire/life/safety, and you could have just as well, used an after-set ring, which are, in use, restricted to low voltage, coax and ethernet applications, and not approved for high voltage.

As example; https://www.homedepot.com/p/Carlon-...ow-Voltage-Old-Work-Bracket-SC100RR/100160916

That galv. pipe will shortly elbow to a roof vent, which can be seen from the exterior, as a locator, which will allow you to find the stud bay for your box.

 

[bud16415]

They make shallow boxes for problem spots and that may or may not work with your pipe. They are cramped for space and most likely not deep enough for a GFCI outlet. If the other outlet on the other side of the window is a GFCI you could feed a regular outlet off the LOAD side of that GFCI and the outlet would then be GFCI protected.



I’m not sure if even then it would be code compliant as that new outlet would be sharing the total ampacity of that circuit. It could be a case where you would plug a microwave into one and a toaster oven in the other and be tripping the breaker.



Under no circumstances would I alter the box in a way that leaves it open behind the wall.



If symmetry is important maybe conceder moving the location of the other outlet at the same time. Sounds like drywall patching and painting will be required anyway.



Sometimes a wider photo showing the whole area along with the close up helps folks here trying to offer their best advice come up with ideas that may help.

 

[PJB12]

As a master electrician, teacher and former inspector: I vote with the others. Never alter an enclosure.

I have testified as an arbitration witness at hearings when there was a fire and the insurance company did not want to pay because a box was altered- even if it had nothing to do with the fire. Something as seemingly harmless as a screw through the side of a plastic box can void your insurance payment. Insurance company won every time.

No matter what size box you choose, do an on-line search for NFPA 70 Article 314.16(a). It'll show you how to calculate if your intended wires and devices meet fill requirements. (Also try searching Box Fill Calculator. I think Omnicalculators com has one.) In crowded boxes, conductors and devices get hot.


To gain space & stay 1-1/2" deep, you can cut in a multi-gang steel box with a plaster ring ("Mud Ring"). This gives you more box fill space, but still only the switch and receptacle outlet show on the wall. Example: 4-Gang box with a 2-Gang mud ring for a switch and a receptacle outlet. The rest of the box is behind the plaster.

Also made are shallow boxes with the device(s) built in at the factory. They are for mobile homes with 2 x 3 wall studs. Be sure it is UL, ETL or other listed.


If you're against using a steel box, I suggest fiberglass boxes versus PVC. They are far more rigid, have an excellent fire rating and the screw holes never strip. A sample sales sheet from Allied is attached. I've seen them with ears, so you can use madison supports if desired. (Don't know the brand of those)

Paul

 

[vyacheslav]

As a master electrician, teacher and former inspector: I vote with the others. Never alter an enclosure.

I have testified as an arbitration witness at hearings when there was a fire and the insurance company did not want to pay because a box was altered- even if it had nothing to do with the fire. Something as seemingly harmless as a screw through the side of a plastic box can void your insurance payment. Insurance company won every time.

No matter what size box you choose, do an on-line search for NFPA 70 Article 314.16(a). It'll show you how to calculate if your intended wires and devices meet fill requirements. (Also try searching Box Fill Calculator. I think Omnicalculators com has one.) In crowded boxes, conductors and devices get hot.


To gain space & stay 1-1/2" deep, you can cut in a multi-gang steel box with a plaster ring ("Mud Ring"). This gives you more box fill space, but still only the switch and receptacle outlet show on the wall. Example: 4-Gang box with a 2-Gang mud ring for a switch and a receptacle outlet. The rest of the box is behind the plaster.

Also made are shallow boxes with the device(s) built in at the factory. They are for mobile homes with 2 x 3 wall studs. Be sure it is UL, ETL or other listed.


If you're against using a steel box, I suggest fiberglass boxes versus PVC. They are far more rigid, have an excellent fire rating and the screw holes never strip. A sample sales sheet from Allied is attached. I've seen them with ears, so you can use madison supports if desired. (Don't know the brand of those)

Paul

This is great advice. Thank you!

 

[PJB12]

This is great advice. Thank you!

You are welcome.

In case you're interested in the shallow device with a box built in, attached is Hubbell's Wirecon brochure page.

Ask your local inspector if they will be allowed in your location. I've noticed a few in houses. (They used to be easy to spot because there are no cover plate screws, but now made are snap-on covers for any device.)

I hope your project goes well,
Paul

 

[afjes_2016]

You may want to try one of these. It is very shallow and has room for wiring to the side.
It can be a bit of a hastle sometimes to insert the box into the wall cavity if the wall surface is too thick. You may have an issue also inserting it because you have to swing it to the side while inserting it and it may hit the pipes behind it. But you can give it a whirl. Buy a couple, try them, if they don't work simply return them. They are old work boxes with the tabs so you don't have to secure them to a stud.

However, the depth of the boxes are a challenge if you attempt to insert a GFCI into them. As suggested above if you replace a regular receptacle just upstream of this receptacle where a regular receptacle would go into this shallow box and wire that upstream GFCI on "load" this regualr recept then is GFCI protected. Just place a label on this receptacle "GFCI protected" which come in the boxes of Gfcis. Or you can change the breaker for this circuit to a GFCI breaker.

Old work shallow box with side car

 

[Snoonyb]

And yet, for all/any of the alternatives offered, you'll need to clean the cut, the measure the depth to the pipe, and select from there.

Even a perfectly centered boring in an 3-5/8" 2X, with 5/8" DW, will leave you with little more than 1.5" to work with. You may even elect to drive a wedge into the boring, and gain another 1/8" too 1/4", possibly.

 

[PJB12]

Way up in Post #3, you mentioned this: "I chose that specific location for the box based on switches and outlets on the opposite side of the window so things would look even (so the appearance would be "mirror images" of each other when looking at the window)."

Personally, I understand your desire to maintain the mirror image.

Instead of driving yourself crazy trying to fit a box to match the mirror side, perhaps consider picking a spot where the appropriate size box will fit and move the mirror side boxes to match, thus preserving your mirror image.

You'll already have the tools & materials for wall patching in the room, so what's one more hole to patch? (Hopefully not much!)

Paul

PS: The box that Afjes_2016 mentioned in Post 13 will have the cubic inch rating molded inside. hallows are pretty small on cubic inch capacity. Use this figure to ensure your conductor fill calculation meets the size. (Nope- You can't use length x width x depth. Have to use the manufacturer's number.)