Will I find an arc-welder connected to the other side of those wires?
Seems like what the tenant in my grandmother's house in Colombia was doing to power the arc welders in his shop.
He had banged a couple of nails to the old wooden pattress that held the whole-house disconnect knife switch (this was a house built in 1949 so you can imagine the type of wiring). These were somehow connected to the switch.
Did you need to use an arc welder? Just hook the wires over the appropriate nails in the pattress!
only problem i see here is that the nails look rusty, better off with stainless steel, also the second nail looks smaller, i would have used a matched pair of nails, with each nail - nailed into a seperate block of wood seperated by plastic or some other insulating material, Oh just another thought the top nail holding the board up looks like it needs another few hits, other than that i see no problems