[kpbarker]

12 AWG to GFCI to 14 AWG. OK?

[kpbarker]

Is 12 AWG to GFCI to 14 AWG OK on 20 amp breaker?

[donf]

It is permissible to combine a 12 AWG cable to a 14 AWG cable, providing the amperage of the circuit does not exceed 15 amp.

It is a serious fire hazard to run 20 amps through 14 AWG cable!

[hkstroud]

NO.
14 gauge wire is only capable of safely carrying 15 amps of electrical current. Therefore it must be protected by a 15 amp or smaller breaker.

[Missouri Bound]

Although it can be done if you follow the proper circuit ampacity guidelines, it's not a good idea to do it. Let say that you start with 12 ga. Wire at the panel, the after a gfci you drop down to 14 ga. Anyone opening up the panel would make the false assumption that it is a true 20 amp circuit and provide overload protection based on the wire size. That immediately creates a potential hazard.

[hkstroud]

The answer is still no.

The question was

Is 12 AWG to GFCI to 14 AWG OK on 20 amp breaker?

OP revised the question in second post.

[stanfortyman]

Also, if you take certain circuits, like kitchen, laundry, bath, and reduce from a 20A breaker to a 15A not only is this foolish because you are reducing the capacity of the circuit needlessly, you might also be creating a code violation. Receptacle circuits in these areas are required to be on a 20A circuit.

Bottom line is there is really no vaild reason to reduce from #12 to #14 on almost any circuit.