Not so fast.
It's a tap.
It may not be a legal tap. You have to follow the tap rules.
With protection of 400A ahead of 200A conductors you're permitted a run of 25 feet until reaching suitable OCPD -- in this case, 200A fusing.
That limit is applied separately for each tap -- and every phase or leg of that tap.
IIRC, there is a provision for longer lengths if and only if the conductors "outside the building" -- as in buried or encased in concrete. I've never pushed that to the limit except for one solitary fire pump circuit.
These are unique -- life safety -- circuits. Meaning that the conductors are not protected by OCPD from overloads in any way. The only 'protection' that such feeders get is from horrific bolted shorts -- and the need to interrupt power for service testing of the controller.
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BTW, though your feeders need to follow the tap rules, very few j-men would ever refer to such (feeder) taps as taps. In everyday usage the implication is that a 'tap' is that short conductor that goes from a wire nut junction to a load such as an electric range or lighting fixture.
The NEC DOES define such massive conductors as taps -- under the tap rules. I've known many a j-man who didn't know the tap rules, BTW. They are the kind of thing that never 'crosses his desk.' Feeders are normally sized and laid out by the foreman. So all of that 'book learning' fades into mist.
