So I went to Lowe’s to see Their selection of double outlet boxes and came across old construction and new. The new construction had nails on the outside. So I thought hey I’ll try it since I can access from behind the drywall. It was going smooth but honestly it was so hard to nail without hitting the drywall and still keep a nice flush setup for front of the box. The old construction had these flaps that go into the drywall and I liked that idea since it ensure it was flush but I hate the fact it’s not screwed into the stud. Soo I seen a electrician on YouTube use these new construction boxes but do the screw on the inside. However, I googled this and people say it’s against NEC for a conductor to screw inside the box to outside. However all the post I read are about using metal screws. Well that got me thinking why not just use plastic screws and problem solved? Also those Madison screw in boxes I did not like those when I tried them as they start to sink back as you screw. Maybe I just suck with them but the idea above gave me a perfect fit I’m just curious if I should be worried since the screw concept is still unanswered if allowed.

Edit: well looks like there aren’t any plastic screw options. It seems nec code in 314 says you can screw from one side of the box so I am curious if this method is now allowed. I was considering keeping it and just using electric tape over screw head. Or should I just remove the screw and assume the drywall can take the beating of plugging stuff in and out?

  • What kind of 'plastic screw' do you imagine would screw into a stud?
    – brhans
    Commented Jan 10, 2021 at 3:44
  • I feel a bit dumb as looking more closely the deck screws are not a plastic material and are in fact zinc coated. Well I have edited my post above to modify my point or idea to make this work.
    – Qiuzman
    Commented Jan 10, 2021 at 4:04

1 Answer 1


Man, you guys just looooove your plastic boxes. You'll do anything to keep em.

I'm a metal conduit guy and it would never occur to me to use a plastic box.

Using a screw to attach a box to a joist isn't even a problem in my world. No inspector would flag a metal box for that.

The screw holes you use, they're either pre-made or you drill them (set that drill on FAST and push hard)... and that's fine, you're allowed to do that. Metal is inherently strong enough.

Plastic you have to attach it at its designed anchor points or it'll crack.

If you're going through drywall with a metal box, you buy the (typically a 4x4) box and an appropriate 1-gang or 2-gang mud ring. The 4x4 boxes have more room than a 1-gang box. The drywall hole only needs to be as big as the mud ring - NOT 4x4.

If you need great gobs of room, you use a 4-11/16" deep (2" or 3-1/4" deep) box again with a 1-gang or 2-gang mud ring. Again hole is only 1 gang in size but you have lots of cubic inches behind it.

  • I thought about using a metal box but from my understanding that would require a metal conduit cable to clamp in. I’m issuing non metallic Romex 14/3. It’s interesting a metal box it’s okay but not a plastic box that are inherently strong too. Looking at more recent nfpa 70 book I have it looks like language has been added saying you can screw from the side of the box. Not sure if I am reading it wrong...
    – Qiuzman
    Commented Jan 10, 2021 at 3:58
  • 1
    You can have NM cable going into a metal box. Doesn't that happen in your breaker panel? Same thing with any junction box. Just need the right kind of clamp. Commented Jan 10, 2021 at 4:11
  • @IrishRedneck -- you can use the "button" style plastic NM clamps (Arlington Black/White Button, Raco Insider) if a metal clamp is problematic for you for whatever reason Commented Jan 10, 2021 at 4:16
  • Thanks . I’ve used one recently on a metal light fixture and call me crazy but those mar up the Romeo wire like crazy. I’m paranoid about nicking the insulation but As I pulled I just kept watching it scratching the heck out of it. Might be overly paranoid doing this electrical stuff. I feel like I grasp what I’m doing but just rather be overly cautious and trying to go by code it’s so open to interpretation it’s crazy. Back to your meta box idea. Can you use the metal clamps on the non metallic Romex according to code?
    – Qiuzman
    Commented Jan 10, 2021 at 4:25
  • There are clamps designed for exactly that. Like: homedepot.com/p/… If you do it right, you're getting the Romex cable in place exactly where you want it with the clamp open and then tightening it. No scratching. Commented Jan 10, 2021 at 4:44

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