I have a 1950s house that has narrow wall boxes, they are about 1-7/8" wide inside, not 2". The boxes are metal, with a metal conduit, in this case there's no ground wire but the conduit is grounded (some others have ground wires).

I'd like to replace some outlets with USB power outlets (Leviton T5632), but they're wider than a regular outlet, about 46 mm or 1-13/16"
enter image description here

The USB outlet fits but scrapes on both sides of the wall box when it's pushed in, which makes me wonder about clearance to the screws.

The screws are recessed and there are plastic shoulders that prevent them getting too close to the walls of the box. When they're tight there' 1/8" clearance.
enter image description here

This isn't so much about inventing some protection that would appear to do the job - plastic sheets with the correct dielectric strength and creepage distance, etc. That might work but could also go wrong later.

My question is whether it's normal or allowed by code that the plastic stand-offs rest against the metal wall of the box? Are they designed for that, and safe when doing that?

  • 2
    Can you provide the brand and model number of the receptacles. In this case we need to look up the listing information. There are listed receptacles that can be used with narrow boxes but the electronics may require a larger box because of the heat generated. So there is nothing wrong with the plastic touching, but the listing may require a larger box. Your location in the world may also affect the answer so please include country and state or local area.
    – Ed Beal
    May 23, 2021 at 18:47
  • Metal or bakelite (brown plastic-like) boxes in the wall? Ground wire or not? May 23, 2021 at 21:35
  • 1
    Yes, the receptacle's instructions may state whether a ground is required. Isn't necessarily a wire, some wiring methods use metal conduit as the ground path, or a metal wire jacket or strand that doesn't come inside the box. May 23, 2021 at 21:39
  • If I must, I would wrap that open side with 3M electrical tape first. I would also want to replace that circuit's breaker with an AFCI to sleep at night without worrying about any ill effect from that side one day touching the case.
    – dandavis
    May 23, 2021 at 22:29
  • 1
    Simple solution: don't install USB outlets. The power they're capable of supplying today will be out of date tomorrow. The 120V @ 15 A of power coming out of the 3-prong outlet will work with every wall-wort charger shipped with a product available in the US for decades (centuries?) to come. That wall-wort will supply the necessary voltage & amperage to the device it shipped with to effectively charge it.
    – FreeMan
    Sep 13, 2022 at 13:35

2 Answers 2


Sorry to point this out, but page one of the manufacturer's instructions states:

This device is to be installed in a wall box measuring at least 3" x 2" x 2-1/2"

Here was the link for reference:


The "1-7/8" wide inside" sounds very close. Is this a 4x2 handy box? Is it 2.5" deep? (Many are not)


Wrap the usb duplex with black tape to cover the screws. I had this issue in a 1950 house.

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