They are independent and would simply compete as to which tripped first as they both operate on the same principle - much like putting 2 fuses in line. GFCI breakers detect when the hot and neutral wires don't have the same current in opposite directions, indicating a loss of current to ground (hence ground-fault) usually a few milliamps of difference.

The GFCI breaker will protect the entire branch while the GFCI receptacle will only protect that receptacle, but if it trips it means a longer walk to the breaker box to reset it. The other advantage of the GFCI receptacle is that it is easier to test and the user will know the items in the receptacle are protected.

And remember that GFCI outlets age. They don't last forever.

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P.E. Metallurgy, consulting work welcomed

Thanks... didn't know that about GFI

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

This seldom happens now, but in homes so old that there are no ground wires at the receptacles, a GFI receptacle or GFI breaker will still provide protection.
The only ground connection that the GFI function uses for operation is the main bond between the incoming neutral and the ground electrode or grid.
A GFI receptacle does NOT need a local ground connection to provide protection.
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Ohm's law
Not just a good idea;
It's the LAW!

I think the bigger issue is that many GFCIs typically daisy-chain a bunch of other outlets under their protection, i.e., one GFCI might protect all of the outlets in a garage, while another might protect all of the outlets in the kitchen, etc.

TTFN (ta ta for now)
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