Outlet 'spacers'

[Michael R. Boyett]

Can someone please explain the requirements and use of 'spacers' at electrical outlet boxes? My understanding is that in certain instances a trim ring or extender of sorts may be needed at a j-box, that is recessed too much into the wall, to maintain the gap (1/4"??) caused by that recessing of the box and the cover plate. Now, certainly that would seem like it would be outside the scope of a typical home inspection to even think about something like that but, trust me, I have ulterior motives for understanding this concept better. If what I'm asking is not clear to you then that's OK, I probably don't need to know that (Bob), perhaps only the sparkies will now what I'm referring to and can explain it. Are there any sparkies left on the message board?

Note: I think I have subsequently found the answer to my question and would delete this post if it allowed me to.

From NEC:

"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."

[gbeaumont]

Originally Posted by mboyett

Can someone please explain the requirements and use of 'spacers' at electrical outlet boxes? My understanding is that in certain instances a trim ring of sorts may be needed at a j-box, that is recessed too much into the wall, to maintain the gap (1/4"??) caused by that recessing of the box and the cover plate. Now, certainly that would seem like it would be outside the scope of a typical home inspection to even think about something like that but, trust me, I have ulterior motives for understanding this concept better. If what I'm asking is not clear to you then that's OK, I probably don't need to know that (Bob), perhaps only the sparkies will now what I'm referring to and can explain it. Are there any sparkies left on the message board?

Michael, I can think of only 2 reasons for extending a J box, the first is to correct the relative depth of the box to the drywall, the second possibility is to increase the boxes fill capacity.

As an inspector I would make no note of them unless I felt there was something weired going on (such as a second layer of drywall installed over existing to hide something) I have seen that done. Having said that unless you are removing coverplates (which I sometimes do) you aren't going to find it.

Regards

Gerry

[Jeffrey R. Jonas]

Gerry,
Perhaps Michael has run into this scenario, as I find this quite often. A coverplate is missing on a wall (sheetrock) that is covered (overlayed) with wood paneling or T&G Pine, Cedar, BeadBoard, etc... resulting in an increased depth to the j-box of 1/8" to 1/4", occasionally more.
Jeff

[Michael R. Boyett]

Yes, that is the scenario guys. As you may have heard on other threads Texas has recently adopted a new SOP and a Commentary is being written for that SOP to further explain it. One of the proposed paragraphs of the Commentary concerned this topic but it has been deleted for now. Obviously it would require the removal of all or at least a sample of cover plates or maybe those that are more likely to have this scenario. Anyway, thanks for the replies and look for my thread on the Commentary in the Texas section of the board and I'll explain this in more detail.

[Jim Port]

It is not really to maintain the gap, but more to limit the gap to no more than 1/4" in non-combustible surfaces. This is to limit the chance for an arc or spark escaping into the wall cavity and starting a fire. It also provides a more secure mounting for the device instead of relying on the coverplate to hold it securely.

As a side note, the maximum gap around the sides of the box is limited to 1/8". The surface should be patched to correct this if larger than 1/8".

[Michael Thellend]

Hi Michael,

The main purposes of an extension ring on an a J box is to protect the insulation of the conductors from mechanical injury, provide protection for the receptacles terminals and to provide better electrical continuity for the ground. All of the aforementioned will help prevent igniting any combustible material surrounding the outlet.

An extension ring is required if the J box is recessed more than 6mm or .24 inches, approximately 1/4 inch.

Mike