This photo shows the jumper cable installed across the gap between two of the modules. The layout is on its side so you have to imagine looking at this from below to get a sense of what’s going on. You can see the way the wiring terminates in the white nylon terminal block on the left with the wire running out the other side up to the socket. The jumper cable is a separate unit that can be unplugged and packed away for transport. No cables dangling from beneath the layout to be trodden on and damaged. Of course I suppose I could possibly forget to take the cables with me to an exhibition but the terminal blocks could then be temporarily hard wired to bridge the gap. The spare holes I’ve drilled in the socket panels are obvious.