Right, but ampacity is still separate from voltage, though they are related. IE, you can have a clamp that is rated for sustained 800A at 12V DC, but it wouldn't still be able to carry sustained 800A at 240V AC, right?
By the way, I'm speaking only of the clamps themselves here and merely the difference in rating for DC vs AC. For the sake of this specific example, I'm not worried about the wires themselves. Though I suppose it doesn't really matter if they're legitimately rated for what the clamps are.