There's the one looong one which the tank will be sitting along, and their are the ones running the opposite way, a few of those so they will be underneath the tank if you understand what I mean? I can't see the floorboards, just tried and check, carpet is pretty much stuck down, but here's a pic of under the house roughly where the tank will sit (Ignore the cobwebs!)
So tank will be sitting along the beam with the cable running along it.
It won't be running along the outside wall, it's an inside one, because the outside has too many windows.