beanland
Senior Member
- Location
- Vancouver, WA
I work on the design of utility scale PV systems. I was browsing my 2011 NEC and noticed 690.11 that requires arc fault circuit interrupters for DC circuits in PV systems. I had never heard of anything like this existing. In a Google search, I see that Eaton admits that no such product exists but they are diligently developing something. Here is a case of "the cart before the horse."
In PV systems, the correct way to "interrupt" an arc fault is to short the output of the PV panel; this eliminates the source of energy and quenches the arc. PV panels are current limited, the short circuit current is about 5% more than the operating current. The NEC requires wire sized for 125% of the short circut current so wiring can be continuously shorted with no ill effect.
So, the 2011 NEC requires interrupting the circuit, which generally means opening it, but what you want to do is short it.
Has anyone seen any product development announcements for DC AFCI for PV systems?
In PV systems, the correct way to "interrupt" an arc fault is to short the output of the PV panel; this eliminates the source of energy and quenches the arc. PV panels are current limited, the short circuit current is about 5% more than the operating current. The NEC requires wire sized for 125% of the short circut current so wiring can be continuously shorted with no ill effect.
So, the 2011 NEC requires interrupting the circuit, which generally means opening it, but what you want to do is short it.
Has anyone seen any product development announcements for DC AFCI for PV systems?