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Just installed a “used” Gfci circuit breaker on my panel. New CB’s not made for this older panel. Without a load wire even attached, CB will not hold and instantly trips when power is applied. Pig tail neutral attached to neutral bar. When I disconnect pigtail from neutral bus, CB will hold when power applied. So, what gives? Bad breaker or something else? Thank you for any response.

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    Pictures and/or make and model of panel needed. Right now choices are bad breaker, wrong breaker for panel, problem with circuit, and/or bad panel.
    – crip659
    Mar 20, 2022 at 23:03
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    Is the neutral wire for that circuit connected to the bus bar or the breaker. If it is connected to the bus that is exactly what I would expect.
    – Gil
    Mar 21, 2022 at 0:50
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    What make and model is your panel, and what make and model is the breaker in question? Mar 21, 2022 at 1:10
  • @Gil the question states "without a load wire even attached" So there's no circuit connected at all.
    – Ecnerwal
    Mar 21, 2022 at 1:57
  • "New breakers are not made for this panel" sounds like you may not have the correct breaker for the panel. Just because you can make it fit doesn't mean it's safe. Another request for clear, focused pics of the label on this breaker and the labels on the panel.
    – FreeMan
    Mar 21, 2022 at 12:12

1 Answer 1

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You hooked it up incorrectly.

You have connected the circuit neutral to the neutral bus, the way plain breakers have connected since time immemorial.

That's wrong for a GFCI. Read the instructions, which you can get off the Web. NEC 110.3(B).

With neutral pigtail connected to the GFCI, it is able to function. It sees current moving through it on hot, but does not see any opposite current on neutral. (since it's not "in the loop", literally).

Circuit neutral is not going through the GFCI, it's going straight to the neutral bus, bypassing the GFCI.

GFCIs work by comparing current on all the active conductors - hot(s) and neutral. If currents are equal and opposite, all is well. A difference in current means some other path is being used, e.g. through a human being. And they trip.

When you disconnect the neutral pigtail, the GFCI loses power and is inoperative.

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