Working on my first electrical project (laundry room conversion), so all of this is new to me.

I'm splicing one 20A and one 30A circuit within a steel junction box to transfer from NM-B to THWN-2 for feeding through LFNC conduit to my outdoor breaker panel. In my reading of NEC 2020 250.148, I should be able to splice -- in my case with WAGO connectors -- each circuit's grounding wire together with the junction box's grounding pigtail and a single THWN-2 grounding wire that exits the box for connection to the panel's grounding bar. In this configuration the pigtail and exiting grounding wire would be 10AWG, matching the conductor sizes in the 30A circuit. Does this meet the code requirements?

Here's an illustration of the plan: enter image description here

1 Answer 1


Yes, there are some other quirky other ways you could do it, but what you have shown is the normal method.

  • I was under the impression that the ground from the panel should go to the box first and then to the Wago. Am I wrong?
    – DoxyLover
    Commented Jul 12, 2023 at 15:32
  • I have seen in these forums answers saying what @DoxyLover says. I have also seen the OP's method is ok. With lever nuts I like OP's method because the box tail can be prepared in advance but still remains connected even if either of the NM grounds needs to be removed. The 221-615 is expensive ... kudos to OP for using one.
    – jay613
    Commented Jul 12, 2023 at 15:44
  • I have recommended looping around the groundscrew on the way to the connector mostly to reduce the number of wires in the connector, but that doesn't even work with stranded wire. In hospitals where HCF grade stranded MC cable is used we often prefab every box with pigtails. Commented Jul 12, 2023 at 16:10
  • My goofy solution in a similar scenario was to use ground lugs that have a screw attachment for the wire and send them all to the box. That way I can remove or attach each conductor from the box without disturbing the others, if I ever need to. OP's solution is simpler and I wish I'd thought about it, because the WAGO is cheaper than three quality ground lugs were.
    – KMJ
    Commented Jul 12, 2023 at 17:52
  • @Doxy if you have the spare ground screws on the box, sure. But I wouldn't loop the ground wire around the box terminal and then go onward to the Wago, because that will turn into a bad hair day with stranded wire, and solid core THHN sucks to pull, esp. in flex conduit. Commented Jul 12, 2023 at 19:00

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