"emichael" wrote in message
ups.com...
I had run a 12/3 w.g 220v circuit to my attic, and then branched into
two 12/2 w.g to run 110v to each of two separate GFCI-protected wall
outlets. Originally I had a ganged double pole 20a 220v breaker
supplying this paired circuit, and all was well. And the electrical
inspector was content.

But then a different electrical inspector told me that instead i needed
to have AFCI breakers in the breaker box, since these outlets are in
bedrooms. So, I bought two 20a AFCIs (I could find no double pole 220v
AFCIs and the guy at HomeDepot said with this situation they should
have been on two separate breakers anyway.)

Well, now the AFCIs trip (both of them simultaneously) whenever there
is any load on either circuit. My guess is that because there is a
shared neutral, the AFCIs are getting confused. But I am also
wondering if the problem might be because there are GFCIs at each
outlet. Can GFCIs and AFCIs cooexist okay? If so, then is there a way
to use AFCIs in this situation?

AFCI contains a 30mA GFCI. You cannot use GFCI with a shared neutral. It
wants to see equal current on the neutral and the hot. With a shared
neutral, there is no way to make it work. Like you said, the GFCI (within
the AFCI) is confused.

If you want AFCI, you need to have two 12/2 circuits. In the future perhaps
someone would make AFCI receptacles you can installed in the bedroom, or
double AFCI breaker specifically for shared neutral ciruit.