I'm very new to all this but figured I could handle turning off the power and installing the hot/neutral/ground on a new and too-large USB outlet. I didn't get very far. This is how I found it when removing the face plate:

I was planning to use the plastic box as it would allow me to screw back into the stud, avoid drywall fasteners, and give ample room for the wiring USB outlet. But I'd be switching from steel to plastic. Is that a no go, and I should replicate what exists with a steel box (an example also linked)?

Is there a different work box I should use? The drywall is fragile, I prefer to attach to the stud (does a steel version exists of the linked plastic angled-screw one?)

If the plastic box is okay, can I pigtail / use a push-in to connect the blue-circled and orange-or-green circled ground wires. (The blue goes to an outlet box for the front porch just behind it; the orange goes nowhere; I'm not sure its purpose).

I may be overthinking this a bit, but it's easy to see people cite NEC and begin to think: why not ask?

EDIT: Thank you to ALL the responses. I really appreciate it.

Steel old-work box
Click to embiggen

Plastic new/old work box
Click to embiggen

Existing wiring in metal box

Different view of existing wiring in box

  • 1
    Plastic or metal box should be okay. The problem with plastic boxes is that you need a ground wire connected to the outlet/switch, metal boxes it is usually an option(the box becomes a ground path). Both types of boxes are made to mount to studs. Turning off the power is the best idea, some people don't.
    – crip659
    Aug 30, 2022 at 15:09
  • 1
    It's hard to tell for sure, but it appears that there are 3 cables in this box. One from the top (and clamped), one from the bottom (and clamped), one from the back (and NOT clamped). That third cable will need to be properly clamped in the new box for strain relief. With a metal box, all 3 grounds should be attached to the box itself to provide a ground path. Most outlets are self-grounding so when you screw them to the metal box (remove the paper/plastic spacer) they'll automatically be grounded and you won't need to attach another wire.
    – FreeMan
    Aug 30, 2022 at 15:35
  • 1
    The fact that your two ground wires (back & bottom, it seems) are just loosely twisted together and aren't connected to anything else means that they cannot be relied upon to act as a ground for whatever they're connected to.
    – FreeMan
    Aug 30, 2022 at 15:36
  • 4
    A plastic box is not, in any way, better than a steel box. Arguably the opposite. The only thing it might be is cheaper (in all senses of cheapness.)
    – Ecnerwal
    Aug 30, 2022 at 15:58
  • 4
    I'm going to give you some advice you didn't ask for: Don't install in-wall USB outlets! Every new generation of phones, tablets, and devices for all of history has come with new generations of charging technology. The plugs and sockets keep changing, and the power capabilities keep increasing. The beauty of a 120V outlet is that with a USB adapter it can charge anything. The phone you buy in two years will not charge at its max rate with the in-wall USB you install today. But you'll be able to buy an adapter for $15 that you can plug into any outlet that will charge it fast.
    – jay613
    Aug 30, 2022 at 16:29

3 Answers 3


Depending how much you have to tear up the wall to get this box out, you may be able to use a new work box with stud ears if you'll be patching drywall anyway.

With less of a hole, a plain steel 2-gang or 4 or 4-11"16" square box (no ears) is easily screwed to the stud beside it by screws driven from inside the box with a ratchet. A show-off might manage nailing them without causing more problems, or they might screw up and look foolish. I don't advocate being a show-off or emulating them. Choose your path on that front.

I don't think anyone makes an "angle screw steel box like the plastic ones" because steel boxes don't need such foolishness to be mounted to a stud.

I will unabashedly state that steel boxes are superior to plastic ones on every measure except a few cents of pricing per box. They are more durable and stop fires a whole lot better than a chintzy plastic box. I do not have any affiliation with any steel box maker, I just have learned a thing or two over time (I used to think plastic ones were all "modern" and "cool")

  • 1
    Modern and cool usually sucks.
    – crip659
    Aug 30, 2022 at 19:43
  • 1
    I used to think plastic ones were safer because I couldn't short out an outlet/switch against the metal side. I've since learned that if I was doing that, then my box wasn't big enough.
    – FreeMan
    Aug 31, 2022 at 14:21

What you have right now is a steel box attached to studs, am I correct? That's what you want. Steel is the best performance box available, especially in light of your concerns about insertion force vs. weak drywall.

For extra space

If your trouble is limited space in the original box, there may be an easy answer: an extension box. The most aesthetic is the Legrand Wiremold Surface Conduit Starter Box. It's intended to give side ports to run their surface conduit off of, but if you don't use it for that, I won't tell :)

Otherwise, given your desire to attach it to a stud, I would go with a sturdy metal box. You may notice metal boxes don't give you a variety of mounting schemes like the plastic boxes do; that is true because on a metal box, you can improvise your own. Welded or drawn metal boxes are strong enough that you can run screws through them almost anywhere and they'll hold just fine. (This is due to the minimum wall thickness required by NEC for screw engagement, not any desire to make boxes indestructible).

Either use the holes provided or improvise your own. Plastic boxes are fairly flimsy, and they have to be gusseted to match the mounting method that is intended; and anyway, drilling random holes (or ramming self-tappers through them) will crack the boxes.

Take advantage of the existing pigtails

Your old receptacle already has black, white and ground wires pigtailed to the socket. That's fine, that's a legit way to hook up. If you have some idea that you have to break up the pigtail and put 2 whites and 2 blacks on 4 terminals on the socket - no, that's not necessary at all. Really. The prior work was done correctly.

Just at the original socket, detach the 3 wires (black white bare) and place the 3 wires on the new USB socket. You do not need to mess with any wire nut at all.

As for the other wires, leave them alone. Push all of them all the way into the back of the box, leaving just these 3 pigtails coming out of the box for you to work. "That was easy".

Grounding in metal boxes

Now, one more trick. Look at your new receptacle and see if it says "Self-Grounding". If it does, you don't need a ground wire to it - the receptacle will pick up the ground off the mounting screws. (all switches do this, by the way, but receptacles need something a bit better since they are delivering ground to an appliance.)

The grounds should be properly wired as follows: the ground wires in both cables should go to the metal box FIRST. They can either go to separate ground screws, or be pigtailed to one ground screw. If you need a ground wire for the receptacle, then that can be added to the pigtail, or put on another ground screw (if the box has that many).

  • I think OP's new receptacle won't fit in the existing box. It looks like one of those 1930s ones that won't accommodate any modern boxy device and the new thing is a USB.
    – jay613
    Aug 30, 2022 at 20:28
  • @jay613 everyone seems to be assuming that, but I didn't see where OP said that. Well, ok. Aug 30, 2022 at 20:33
  • 2
    My evidence is the word "larger" in the question, the photo of the box, my own failed attempt to put a big device (GFCI in my case) into a box like this, and some benefit-of-the-doubt to OP in that, while people do enjoy unnecessarily detangling wires (I do) ... they usually won't escalate an outlet upgrade into a junction box replacement without some major additional motivation such as, it just won't fit.
    – jay613
    Aug 30, 2022 at 20:43
  • @Jay613 yeah, that does make sense. Aug 30, 2022 at 20:59
  • @Harper-ReinstateMonica Thank you very much! I appreciate your clarity and will work to make any next questions (and answers) more precise. The newer USB outlet is too large, otherwise it's an easy process (even for me). There is by another party a strong desire to have a USB outlet here (and to not use plug-in adapters, despite their future-proofness). Aug 31, 2022 at 18:06

Yes, attached is a pic of a listed plastic box with built in screws to attach to studs. Don't use the push-in (aka backstab) connections, instead, pig tail and connect to the screws on the side of the outlet...assuming it has them. A pic of the new outlet would help.

EDIT: Oops, I didn't scroll in your linked pics and then did, so apparently you already found the type of box I mentioned.

Regarding grounding, you'll simply have to connect the ground to the outlet (usually a green screw).

picture of electrical box with screws

  • Thanks! Do you you mind explaining why the orange wire goes nowhere? Someone left it as a lead for further work? It goes into the ground wire-nut and then nada... Aug 30, 2022 at 15:17
  • @alfredmaul That is a ground wire(bare) that should be attached to the box or wire nutted to the other ground wires. Someone was just too lazy to connect it right or it broke/became loose. Both are bad and you have a good chance to fix it right. I am assuming you mean the orange circles.
    – crip659
    Aug 30, 2022 at 15:44
  • 1
    The bare copper wire with no insulation (is that what you mean by orange?) is the ground wire. In your old metal box it should be connected to the box (your green circle) AND to the outlet. In your new plastic box it would not be connected to the box. You have two ground wires entering the box. Connect them together with a wire nut and a third pigtail wire that goes to your new outlet.
    – jay613
    Aug 30, 2022 at 16:32

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