Electrical Outlets in Cabinetry

Electrical code requires outlets to be installed within properly mounted electrical boxes. April 26, 2006

We do mainly built-ins. Wall units, entertainment centers, and such. Backs have about 1/2" gap from drywall. What's the best way to mount an outlet inside a cabinet or on the back of an open shelving unit? I like to have electricians do the work, but am never sure how they deal with new and existing outlets.

Forum Responses
(Cabinetmaking Forum)
From contributor M:
Code in most places for that type of situation would be for the electrician to put a box extension on. That way, you would be able to put the cover plate inside the cabinet. I've seen a lot of people just pull the outlet through and screw it to the inside of the cabinet. Not a smart idea, nor do I recommend it, but it's been done.

From contributor J:
What's wrong with screwing the outlet to the cabinet?

From contributor M:
Fire hazard, for one. Two, refer back to one. If you have a spark and it's near flammable materials, you'd be taking a chance of having the 4th of July at someone's home.

From contributor B:
I cut an oversize hole and reach through to plug it in. In that way, I don't mess with the electrical. If they want it inside the cabinet, then I have them leave a pig tail and I cut the hole with a router. I still don't install it.

From contributor J:
Outlets are screwed to island cabinets all the time. Is this any different?

From contributor K:
I don't see how the outlet could spark either, if it is wired properly. It's installed in the cabinet just like it is screwed to the box. The wires are exposed the same way, so unless it magically comes unwired and the wires touch, I just don't see how it is different. What we typically do (we use 1/4" backs that are tight to the wall 90 percent of the time) is unscrew the outlet from the box, cut a hole in our cabinet the size of the box perfectly placed over the box, and then pull the outlet through the hole and fasten the outlet back to its original box, but its flanges are inside the cabinet. Now the wires are still in their boxes and the outlet is still screwed to the box, but there is a 1/4" backing between the outlet flanges and the box. Then the plate covers the outlet and the hole as if it were on the wall. I think all that gibberish makes sense. Anyways, I'm not moving the electrical placement or unwiring it. I'm simply moving it forward by extending its screws 1/4". I think if it were going to catch on fire, it would do it no matter what the instance, and that it is a faulty outlet or electrician.

From contributor R:
I agree with contributor M. The purpose of electrical boxes in walls or anywhere is to contain sparking. Any outlets I've seen in islands certainly had a box. If you're going to pull the outlet ahead, why not add the extender and do it right? They're about a buck at HD, and you can put them on without rewiring anything. Even if you don't have an electrician do it, better to do it right and safe. I agree that the chance of sparking is extremely remote, but things can fail and s*&% happens.

From contributor O:
You can probably get away with any of the above mentioned methods, if there is no electrical inspection, but here's what the 2005 NEC requires:

314.20 In Walls or Ceilings
"In walls or ceilings with a surface of concrete, tile, gypsum, plaster, or other noncombustible material, boxes employing a flush-type cover or faceplate shall be installed so that the front edge of the box, plaster ring, extension ring, or listed extender will not be set back of the finished surface more than 6mm (1/4"). In walls and ceilings constructed of wood or other combustible surface material, boxes, plaster rings, extension rings, or listed extenders shall be flush with the finished surface or project therefrom."

Here's an example from the NEC Handbook.
"A wall constructed of wood but sheathed with an outer layer of gypsum board is permitted to contain boxes set back or recessed not more than 1/4". A wall constructed of metal studs but finished with wood panels requires that the outlet boxes be mounted flush with the combustible material."

From contributor A:
I tend to work with the electrician and ask him to leave a wire hanging out of the wall a couple of feet long. When placing the cabinets, I can cut a remodel box into the back of the cabinet and run the wire into that box.

From contributor S:
Get what is called a quickie box, a drywall box, old work box. It's a plastic box with little ears that flop out and sandwich the box to the wall, or the cabinet back - same principle as a mobile home receptacle, easy to use, very common in kitchen remodeling and passes inspection and codes. Just do it like it should be done. Many times I do it for free, making the customer take part in this in some way, letting them know the deal on permits and license and the fact that they can do it on their own house and it is 100% legal, saves them a hundred bucks, takes 10 min of my time, and keeps the work coming in.

From contributor V
I've got a job now where the outlet needs to be moved forward from the wall and attached to the back of the cabinet. I've decided to leave this deed to the customer or his electrician. My understanding is that if there is ever a problem with that connection, I could be held responsible. My general liability covers cabinet work only. Am I right?

From contributor E:
I'm a non-pro and even I understand the purpose of electrical codes. This isn't complicated. Either put an extension on the box or install wood behind or next to the box that you can securely screw or nail it into such that the front edge of the box is flush with the inside of the cabinet. I moved two outlets and added two outlets in my kitchen rebuild, all with blocking, all flush to the inside of the cabinet. No big deal to do. You don't want wood 1/2" away from a potential fire source. You would be potentially liable.

From contributor JP:
Gentlemen: electrical codes are written by the NFPA, National Fire Protection Association. Their objective is to prevent fire. Fire needs fuel and oxygen, based on that the pulling of an outlet out from its metal or plastic box allows air flow into the wall space. The 2017 code still shows section 314.20-22 as the outlet MUST be flush with the surface of the finished wall. Use an extension box or open the wall and have the box replaced with one that can be adjusted (plaster ring) protrusion to fit flush with the wall unit. Secondarily each material has a fire rating. A length of time the materials will withstand the fire, usually 2 hours as a minimum. summary: dont "just pul the outlet to fit onto the wall unit" Use a rated fixture/switch box to do the task, keep the outlet in contact with the box. Either for grounding (it should have a ground wire) or for protection from florigen object (nail...) hitting something live.