@ozzy I looked at the Entreq site and also read the manual for the boxes.
They only have one wire from the component to the box. When a cell is used in a box, it can only be used for one component so there are no other 'ground' wires connected to that cell.
Since only one wire is used there is no circuit- and therefore no current. I think you'll find that the wire is of little consequence. As best I can make out the boxes might act as a sort of opposite of an antenna and is something for which I have either too much education or too little to understand; I found the poorly written (language first English not) explanations offered on the website incomprehensible.

