I would like to install this NEMA 14-30R in a surface mount single gang box for my dryer.

Can I put it into this box?

The box has 19 cu-in.

I am not proficient with fill calculations but 3x10AWG + 1x12AWG grounding I would arrive at 17.25 cu-in.

Hence I think it should be good but I want to confirm.

If not, do big stores like Lowe’s or Home Depot have a box that works?

  • Your links both lead to "Access Denied".
    – puck
    Commented Aug 27, 2023 at 7:48
  • 1
    The box you linked to is an "outside"-style box for conduit and water-resistant/proof installations. Do you want this outlet to be outside in the rain? Commented Aug 27, 2023 at 11:19
  • 2
    Based on the calculator I use, your minimum box size for 3 #10s and a #12 ground, with one device, is 14.8 CI.
    – Huesmann
    Commented Aug 27, 2023 at 12:40
  • @Huesmann thank you! Reason for my 17.25 is "Using a box with internal clamps? Yes". Not sure if this is right though... If not, just to confirm, it's 2x current conducting AWG#8 and 1x AWG#12 ground? Then my calculator (omnicalculator.com/construction/box-fill) would give me 14.25cu-in...
    – divB
    Commented Aug 28, 2023 at 6:25
  • That would explain the difference. The gray box you link doesn't have internal clamps (or clamps at all). But if you use the correct style of box it might, so YMMV.
    – Huesmann
    Commented Aug 28, 2023 at 11:23

3 Answers 3


The links you posted include dimensions, and based on those it doesn't seem like it would fit. The outer metal frame seems too big for the box.

  • Receptacle: 2.46" W x 3.69" H x 2.26" D (reference)
  • Box: 4.97" W x 2.3" H x 3.87" D (reference)

+1 to @manassehkatz's suggestion of using a 4" metal box. I've installed a similar sized receptacle before into such a box and it fit very naturally.

The bigger box will also give you more capacity inside to do the wiring. Assuming three #10 live conductors and one #12 ground, this calculator implies you'll need 17.25 cu in for box fill. In practice though that feels like it would be very tight, especially given how big the "device" is compared to a typical 15/20A receptacle, the amount of slack you'll need to leave, and any awkward angles for the wires to approach the device.


Will that box work? I guess it probably would. But use a metal box instead. See this post for some reasons why.

Typical is to use a 4" box and a cover such as this one from Home Depot:



A frame challenge:

Your linked "Carlon" box is a surface mount box. What about replacing both box and insert with a surface-mount 14-30 outlet?


14-30 surface mount outlet

  • I actually purchased a very similar one already (leviton.com/en/products/55054). But I just don't understand why this is flipped design (as is the one you linked): When plugging in the cable, it comes from the top, not bottom, as usually the ground pin is at the top. Furthermore, it is preferred to have ground on top. Who came up with this design and doesn't even make it adjustable? That's the reason I wanted to get the receptacle and the box separately so I can just rotate it the right way.
    – divB
    Commented Aug 28, 2023 at 6:20
  • FWIW ground on top, as best I understand, is the way regular outlets were supposed to be installed (the little faces should be upside down), so a metal strip falling behind the plug body onto the pins will touch the ground first and either be not energized, or then touch the power pin and pop the circuit breaker. I have also seen these 14-30/50 outlets mounted at the floor edge, so the right-angle plug could only fit pointing up. If instructions allow, maybe you could mount this kind upside down or sideways? Commented Aug 28, 2023 at 14:02

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