Split wires for the purpose of measuring high currents
Figure 1. The Amprobe ELS2A has a mains plug at the top and a socket at the bottom. A clamp-on ammeter can be attached to either side of either hole with the clamp faces closing in the hole.
That device is just a plug and socket connected with, I presume, the live wire running down one side and the neutral and earth running down the other. Clamping on either side should give a reading of the current being drawn by the device plugged into the socket.



simulate this circuit &ndash; Schematic created using CircuitLab
Figure 2. A home-made version.
A similarly functioning device could be made by using plastic junction boxes at the top and bottom connected by two plastic conduits. The input and output cables would use gland fittings where they enter and leave the box.