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The metal double-gang box (40 yrs old) is stripped where you place the 8/32 screws. I should have replace the box in the beginning. It took me an hour or so to put a nut on both of these screws from within (not touching any wires) behind the stripped holes to hold the screws. Do most electricians replace the box or get the next size screws up (10/32)?

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  • Yeah, I would just tap for 10-32 and move on. Just don't nick a wire. – Harper - Reinstate Monica Apr 17 '17 at 18:44
  • Oops didn't see your comment. I will do that. Using a nut worked placing behind the hole that holds the screw or thats not code? Again thank you. Larry – larry pinsky Apr 17 '17 at 21:28
  • Is the nut UL listed and labeled for that use? LOL no just kidding!. It's fine if you can do the finger acrobatics, the problem is I would want to use something more...cooperative... Like an automotive style nut-clip or epoxy the nut there... and that method may not be listed. – Harper - Reinstate Monica Apr 18 '17 at 22:05
  • oops didnt see this comment. It did work with an 8/32 electrical screw and a nut. – larry pinsky Apr 19 '17 at 4:42
  • Another great idea. Almost to the finish line. – larry pinsky Apr 20 '17 at 2:26
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Those boxes are made of mild steel. Skip the tap and just use a sheet metal screw. A self-tapping screw whose drill tip just fits the current hole will do well.

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  • Have to be careful with sheet metal screws as not to violate 314.23(B)(1) – Kris Apr 18 '17 at 12:51
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    I don't see the relevance of that rule here. It involves using screws in holes not intended for mounting. Here I'm suggesting using designated holes. – isherwood Apr 18 '17 at 13:53
  • Well, the main concern is the sharp edges and length of the sheet metal screw. I know it's a common quick fix that usually works fine. – Kris Apr 18 '17 at 14:36
  • Fair point. Self-tapping screws come in two varieties... drill-tip and really-freaking-sharp-tip. I suggest the former, which shouldn't be more risky than the original screws (which sometimes have a self-tapping notch themselves). – isherwood Apr 18 '17 at 15:10
  • A sheet metal screw is not valid as a grounding path unless it's -32 pitch or better. It needs that many threads to engage in order to assure a ground. – Harper - Reinstate Monica Apr 18 '17 at 22:01
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Answer: tap it out one size larger for 8/32 10/32.

Grandfather clause may over rule the following but figured you'd like to know....

First: That box is only rated for 18 21 cubic in. capacity. You got at least 13 conductors, counting each switch as 2 conductors per Code.

  • 14 AWG = 13 x 2.00 = 26 Cubic capacity
  • 12 AWG = 13 x 2.25 = 29.25 Cubic capacity

Plus you're missing a ground jumper which counts as one conductor. (Devices have to be of the self-grounding type to omit bond jumper.)

The switch plate would need to add at least 5 cubic in. for it to work with 14 AWG. Otherwise, you'll need a 1900 box extension to pass muster

Lastly, you maybe wondering about using a larger course screw. While this is a quick fix certain care should be followed not to allow the sharp threads to damage conductors and not to use a longer than necessary screw. NEC 314.23(B)(1) prohibits using screws and nails

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  • Your right! All i was doing is replacing receptacles and maybe some wire nuts. It was passed when i bought 30 yrs ago. Also why would any inspector allow this to happen? Grandfather just like the 15 amps in the washroom though should be 20 amps . Replacing receptacles can be done as long as your not adding wires etc.. Regardless i have two other boxes in a similar fate. For the sake of safety, i will replace them. All the wires are 14 gauge in the picture. We have conduit-- no ground wires needed. So should i buy a mud ring for now? And should i buy 10/32 screws?.thank you truly for helping ! – larry pinsky Apr 17 '17 at 21:14
  • Ye Ole Grandfather clause. Nice one ;-) – Kris Apr 17 '17 at 21:29
  • Don't forget the domed switch cover. That counts. Though the space issue would be excuse enough to swap the box. – Harper - Reinstate Monica Apr 18 '17 at 21:59
  • @Harper See the second to last paragraph i mentioned switch cover may add cubic in. :-) – Kris Apr 18 '17 at 22:11
  • Thank you all. I did purchase a few new deep cubic boxes just in case as well as a Klein multi tap to make it 10/32. But the way i did it originally using a nut behind the broken threaded screws (8/32 electrical screws) is that unacceptable to Nec? Disnt see anything to the contrary. Just curious! Otherwise i will do harper's suggestion for now with the tap. – larry pinsky Apr 19 '17 at 4:38

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