I remember my last code cycle class where it was discussed to afci protect DC circuits. Course I piped up and asked, " how the hell can arcfault breaker protect a circuit that doesnt have a sine wave?" I already know the answer, it can't. Yet it won't suprise me that leviton, GE, and sq D from trying anyway. It just scares me that it seems the nec is getting written more by marketers than engineers.