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I’ve been replacing some damaged receptacles in my dining room and after inspecting all of them on the circuit it looks like they are all interconnected via parallel daisy chaining, but they form a loop via a junction box where the hots/neutrals/ground are pigtailed back to an upstream 20 amp gfci that sits above counter.

Why would these form a loop instead of one receptacle being the last one with no downstream (even if it meets back in that same junction box). These are 12/2 wires with 15 amp receptacles. Is there any benefit to this wiring scheme or is it wrong?

Wiring Sketch

Arthur Branham
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    If they are wired correctly, everything downstream the GFCI outlet would also be protected. – Evil Elf Mar 28 '22 at 12:33
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    First where in the world are you located? In the U.S. a branch circuit is only connected a 1 end but in other parts of the world some of their circuits are in rings or loops. – Ed Beal Mar 28 '22 at 13:29
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    Can you please sketch what you mean with "forming a ring via a junction box and pigtailed back to an upstream 20 amp gfci"? See also https://en.wikipedia.org/wiki/Ring_circuit – P2000 Mar 28 '22 at 13:52
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    I’m in the US. Every other room seems to have them chained serially around the room ultimately with one receptacle box only having 1 wire in. In this particular room every receptacle on the circuit has two wires into the box, except the gfci which is the first in line from the breaker. The gfci output is joined to two hots and two neutrals in the downstream junction box forming this ring as I described. I’ll see if I can sketch it up. – Arthur Branham Mar 28 '22 at 14:59
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    Why don't you call red 'hot' instead of 'black' since it clearly isn't black on the diagram... :-) – TylerH Mar 28 '22 at 17:43
  • And red is a legal hot color, too. Yes, "ring mains" are illegal in the US. Because the way the UK does ring mains is extremely particular. The ring should be cut at some advantageous point. Have you *actually seen* the wiring? Because this type of wiring (not with the ring though) is ideally suited for a **MWBC**. If the GFCI is MWBC-ready, that is, which means a GFCI breaker, or dual GFCI receptacles past the split. – Harper - Reinstate Monica Mar 28 '22 at 18:19
  • I was using dark mode on the iphone so I couldn't draw the black wire...wanted to convey hot, but not confuse with a red 3 wire. – Arthur Branham Mar 28 '22 at 21:54

1 Answers1

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This is completely unusual for US wiring. If you have a "ring", then you must correct that. Possibly by just disconnecting one side of the "ring" from the GFCI permanently.

But: are you really sure that they are wired in a ring? The way to test would be to:

  • Disconnect one side of the "ring" from the back of the GFCI and test ALL the outlets.
  • Then disconnect that side, reconnect the other side and test all of the outlets again.
  • Finally, completely disconnect the "ring" entirely from the GFCI and test all of the outlets.

And here is how you interpret the results:

  • Any outlet that remains on during all three tests is not powered by this "ring".
  • Any outlet that remains on during BOTH the first AND second tests confirms you have a "ring".
  • If NO outlets remain on during BOTH the first AND second tests, then you don't have a ring. The extra wires probably mean that the circuit simply continues on somewhere else.
longneck
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    Not only unusual, they're illegal. See also https://diy.stackexchange.com/questions/212/what-is-a-ring-main – P2000 Mar 28 '22 at 16:30
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    @P2000 They're illegal in the United States. In the UK, rings are the norm, as Q212 explains -- although not a ring off a spur as illustrated in the question: that's likely to be illegal everywhere. – Andrew Leach Mar 28 '22 at 16:39
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    Yes I meant US. Probably not because they are dangerous, but because the NEC has restrictions on parallel wires for other reasons (breaker screw terminal size), and this just falls under it. If the wire is fully gauged (not half sized) there's no overcurrent risk in the event of a lost connection, and what's left as risk is possible EMI. – P2000 Mar 28 '22 at 16:49
  • It’s a 12/2 wire all the way through. So if this proves to be true and I’m not missing some unknown terminal receptacle elsewhere, splitting that junction and capping off one of the 12/2’s would break the “ring” and keep everything chained linearly off the gfci? – Arthur Branham Mar 28 '22 at 17:33
  • Actually funny you bring up EMI. I detected a phantom 1v in nearby circuits even when the circuit breaker is off for them. Could this EMI possibility create induction if the circuit lines are routed close together? – Arthur Branham Mar 28 '22 at 17:42
  • Yes, if you do in fact have a ring, then disconnecting and capping the wires is a fine solution. – longneck Mar 28 '22 at 18:15
  • Ok. I may have jumped the gun here lol. Thank you for questioning my original thought. I double checked and that junction box isn’t tying 3 wires together, only 2. There’s a second pair in there that gave the illusion - they all share the same ground wire only. That other pair is 14ga so it’s likely unrelated. my problem now appears to be where is the end of this circuit that continues on. I’ve checked everywhere with light switches receptacles etc. I’m praying it’s not capped off in the wall. I suspect the end would be the opposite wall of the gfci. What’s the best way to trace it? – Arthur Branham Mar 28 '22 at 19:05
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    Turn off all of the breakers in the house except for the one that supplies the GFCI. Then test everything. But does it really matter? What's the goal of this investigation? – longneck Mar 28 '22 at 19:36
  • @ArthurBranham in light of your recent findings I'd just consider this question answered. It was also informative to the general reader. Mark it as preferred, and if you wish, post the new issue as a new question. – P2000 Mar 28 '22 at 20:00
  • Sounds good. @longneck At this point I'm just curious and I have a lot of spare time :) – Arthur Branham Mar 28 '22 at 21:34
  • Carrying my investigation on here: https://diy.stackexchange.com/questions/246831/how-do-i-locate-the-end-of-an-electrical-circuit – Arthur Branham Mar 28 '22 at 21:52