Are there any industry standards (Engineering Specifications) for the minimum / maximum space required for the electrical box that holds a regular AC wall plug?

Type B grounded duplex outlet

  • The problem I am trying to solve is quite simple - are / is there any local (USA, Canada, or EU) industry standards that require, or set, dimensions in the Height, Width, and Depth (in inches or centimeters) of the space required to be used by the electrical box for an AC wall plug as shown below:
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    $\begingroup$ @KingsInnerSoul Are you asking for the location of the outlet on the wall, or required open space around the well box? The first is controlled primarily by accessibility requirements. As far as I know, the second has no specific requirement - if the wall box fits, you're good. $\endgroup$
    – Ethan48
    Commented Apr 13, 2015 at 15:22
  • $\begingroup$ Yeah, all the wall plugs I see here in the USA (home-depot i.e.) will always fit in the wall, and will always screw in the right place. All those different companies manufacture the same product with and they all fit regardless of the brand. That tells me there has to be some kind of a standard? $\endgroup$ Commented Apr 13, 2015 at 15:27

1 Answer 1


The normative reference for the design of wall boxes for electrical work in the US is NEMA OS-1 for metal boxes and NEMA OS-2 for nonmetallic boxes. This, in turn limits the size that components to go into these boxes (including outlets) may be.

If you don't want to buy the standard, you can find a good bit of information from it posted from various manufacturers, here is one example.

Page A3 of this document explains the limitations on how full the boxes can be, as dictated by NEC 314.16.

As you can see, there are many different sizes and configurations of these boxes, but they have fairly standard front-facing features so that various outlets, switches, or other devices can attach uniformly. When you buy an industrial outlet, the cut sheet will usually tell you how deep of a box it requires, since that's the most variable dimension between boxes.


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