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When a GFCI outlet trips, does it open both the hot and the neutral, or only the hot? An outlet beyond the GFCI outlet has an open neutral and I wonder if that is normal when a GFCI trips?

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    If your testing device is a 3-light tester, it may not have an open neutral at all. The legends are often laughably wrong.
    – Harper - Reinstate Monica
    Apr 8, 2019 at 4:54
  • A outlet tester requires power. If the outlet tester has power you have reset the GFCI feeding it so there should not be an open neutral. But I agree with Harper some of those testers are such a joke I think his magic 8 ball comparison is accurate.
    – Ed Beal
    Apr 10, 2019 at 13:52

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At least three sources indicate that a GFCI outlet interrupts both the hot and the neutral.

The Circuit Detective:

When a GFI outlet trips off, both the hot and neutral "line" terminals become disconnected inside the receptacle from the "load" terminals.

WaterHeaterTime.org:

More importantly, a GFCI receptacle switches off both the hot and neutral sides when it trips; making sure that the hot leg is interrupted even if it was mistakenly attached to the neutral side of the receptacle.

PDH Online:

GFCI are generally designed to interrupt both conductors in case someone has mistakenly wired a circuit backwards and is using the white conductor as the hot conductor instead of the black conductor.

And this source indicates that "it depends".

Voltimum:

Essentially RCBO's are classified by the number of poles and current paths:

  • 1P+N Single pole RCBO with one overcurrent protected pole and uninterrupted neutral (two current paths)
  • 1P+N Two pole RCBO with one overcurrent protected pole and an unprotected switched neutral pole
  • 2P Two pole RCBO with two overcurrent protected poles

Bottom line:
Probable, but inconclusive. You'd need to find the spec sheet of your particular model to be certain.

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  • In the last quote, from Voltimum, the 1P+N is defined twice. I think the first definition is for 1P.
    – Robert Lee
    Dec 14, 2022 at 0:24
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    I'm just relaying what their site said, so I can't be certain. But I think the first two are two different flavors of 1P+N.
    – Doug Deden
    Dec 14, 2022 at 4:10
  • Indeed, it appears to be describing two flavours of the 1P+N, i.e switched vs not-switched neutral. It's confusing they're named the same.
    – Robert Lee
    Dec 14, 2022 at 12:27
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The neutral in a GFCI may not open when it trips. So if you are reading an open neutral, that could very well be part of the reason it tripped.

enter image description here

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  • I would like to know the reason for a down vote (reversed) on a correct answer. There has been a lot of these lately.
    – Ed Beal
    Apr 8, 2019 at 12:59
  • @EdBeal, not the down voter, but it's a very short answer? I don't know, that's all I can think of. (And this still has a down vote - a high rep user like you can click on the number and see the up and down votes)
    – JPhi1618
    Apr 8, 2019 at 18:17
  • @EdBeal -- I'm pretty sure this answer is not correct, actually -- if you look at the reference schematic in any GFCI-chip datasheet, it shows that the breaker breaks both hot and neutral, and that comports with the GFCI/RCD teardowns I've seen as well
    – ThreePhaseEel
    Apr 8, 2019 at 22:31
  • Try and look a few up and provide a reference. I can start with the NEC exhibit 210.6 it shows the shunt trip on the hot and nothing on the neutral. This plus the one he already posted from the web.
    – Ed Beal
    Apr 9, 2019 at 14:01
  • @EdBeal see page 4 here or page 6 here, as well as the photos from this teardown link
    – ThreePhaseEel
    Apr 10, 2019 at 0:32

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