Originally Posted by
Jeff Eastman
I had 4 AFCIs stacked yesterday. They were "buzzing". I don't believe that is "normal" so I punted to electrician to look at it. Also, is it 3 that is the max # of stacked AFCIs?
There is nothing (so far that I am aware of) "in writing" which says stacking them is not allowed.
HOWEVER, all manufacturers I've talked to have acknowledged that 'it's a "good idea" not to stack them on top of each other, that at least one or two regular (non-AFCI) breakers be installed between the AFCI breakers' to allow for heat dissipation.
The newer AFCI breakers are supposed to be operating with a lower energy use (lower heat output) circuit in them, which should eliminate this problem, which is good, considering that it will not be much longer before all 120 volt circuits will require AFCI breakers.