Output wire size from combiner panel

[bbartmasse r]

Here is the situation:

56 SunPower Ac modules on the roof

Combiner panel has (4) 20 amp breaker with 12 modules attached
(1) 20 amp breaker with 8 modules attached

I am running 2/3 romex with ground back the panel. My question is is that wire size sufficient?

I know #2 Thhwn is good to over 100 amps but what about when it's wrapped as Romex? I have never used NM wire of this size so am unfamiliar with the rating.

thanks
Brett

 

[electrofelon]

Here is the situation:

56 SunPower Ac modules on the roof

Combiner panel has (4) 20 amp breaker with 12 modules attached
(1) 20 amp breaker with 8 modules attached

I am running 2/3 romex with ground back the panel. My question is is that wire size sufficient?

I know #2 Thhwn is good to over 100 amps but what about when it's wrapped as Romex? I have never used NM wire of this size so am unfamiliar with the rating.

thanks
Brett

Your wire would have to be sized for 125% of the modules' output rating. Note that it also needs to be protected from overcurrent on the other end as well. NM is sized with the 60 degree column , so that is 95 amps so in conjunction with the next size up rule, it can go on a 100 amp breaker.

Personally, I hate large NM. It is super expensive and has low ampacity. I usually go with AL SER which can be sized on the 75 degree column if not installed in insulation. If you want copper, you could see if your supply house has CU SER, some do.