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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

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    If they are wired correctly, everything downstream the GFCI outlet would also be protected.
    – Evil Elf
    Mar 28 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 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 en.wikipedia.org/wiki/Ring_circuit
    – P2000
    Mar 28 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. Mar 28 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 at 17:43

1 Answer 1

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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.
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    Not only unusual, they're illegal. See also diy.stackexchange.com/questions/212/what-is-a-ring-main
    – P2000
    Mar 28 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. Mar 28 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 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? Mar 28 at 17:33
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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 at 19:36

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