I'd keeo the BP panel close to the devices it serves. If that puts it far away from your main panel, just use something like 8AWG between them. And even if you use Romex instead of pulling separate wires, it's nice to run it in steel flex conduit to protect it from RFI/EMI.
Another trick just suggested to me (and which seems to actually do something!!) is to attach a small sheet (say 5" x 11") of Stillpoints' ERS to the back of your fuse/breaker panel door and also the sub panel door. Really traps RFI.
Another trick just suggested to me (and which seems to actually do something!!) is to attach a small sheet (say 5" x 11") of Stillpoints' ERS to the back of your fuse/breaker panel door and also the sub panel door. Really traps RFI.