Question about combining branch AC circuits
I will have 3 branch circuits, each producing 16 amps, total combined is 48 amps. I am using Emphase M250 inverters. According to the Enphase tech instructions I am supposed to put a 20 A breaker on each of these circuits before combining them at a none fused AC shutoff switch. The cable from the AC shutoff switch to my Service Panel is 4 gauge (calculated to easily handle the total possible 48 amps). That cable then connects through a 60 amp, 240 volt circuit on the Service Panel.
My question is, why to I need the 20 A breakers on each of the branch circuits. It is my understanding that since each of the 3 branches are not only connected in-phase but also in parallel at the AC Shutoff switch. Therefore these 20 A breakers appear to be redundant and not necessary. Seems putting them in the circuits just adds another component to fail and add resistance.
I called Enphase their tech support was unsure, but said that is the way their engineers tested their circuit design, so that is what the recommend.
Need some feedback, thanks,