I tested the outlet with an outlet tester which states that it is properly wired. However, I know that conduit is not necessarily always sufficient to provide a proper ground. So I tested the outlet with a multimeter. I get 120.5 volts when testing the line and neutral, as well as when I test the line to the ground hole on the outlet. So it seems that the conduit is properly grounded.

I need to add an outlet nearby this outlet... but how do I properly tie in a romex cable to this situation?

Unrelated but similar question: I also have several outlets that are not grounded outlets. However, if they are run through conduit that is properly grounded, I might switch out the outlets... But should I instead be rewiring everything? We are closing up the attic floors as we create a master suite in the attic. Seems like the next few months is my last good chance to rewire anything... but I'd rather just switch out the outlets as the time and money invested on that does not seem worth it.


Picture of outlet, box and conduit

  • 1
    Where are you on this planet? It may be that the existing outlet was wired using conduit because local Codes in your area require you to use conduit.... Jan 17, 2021 at 21:54
  • Boston, Massachusetts
    – user128804
    Jan 17, 2021 at 22:59
  • You should be considering box fill. In order to add a 12/2 to the existing box it would require a box measuring at least 20.25 in³ or if all #14 then 18.0 in³. So a 3" x 2" box would need to be 3.5" or 3" deep box, And that's not considering what appears to be some funky conduit fittings that may impact the calculation. Jan 18, 2021 at 15:55

1 Answer 1


If the box is grounded by the conduit, you can get self tapping grounding screws and screw one into the hole in the back of the box. Then wrap your ground from your NM cable around the grounding screw and tighten. Use the proper NM to box connector. Make sure you're not in an area that requires conduit. In my humble opinion, the wiring shown in the lower box should be replaced if you're in a position to do so. It's old and will start breaking up if you mess around with it. As far as the grounding goes, if the box is grounded, you can replace the outlets with self grounding outlets and they will get grounded when screwing them into the box, or you can add a grounding wire to the box and attach it to the outlets.

  • “Wrap your neutral around the grounding screw”?? I hope you meant to say “wrap your ground...” there.
    – nobody
    Jan 18, 2021 at 0:38
  • Glad I'm not crazy. That was the only part of the reply I did not understand... :-)
    – user128804
    Jan 18, 2021 at 0:46
  • @nobody Good catch, just finished an answer about neutrals and had them on my mind. :-)
    – JACK
    Jan 18, 2021 at 1:01
  • @user128804 My bad.... Watching football at the same time. :-)
    – JACK
    Jan 18, 2021 at 1:02

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