Copper
 

Here is what l do... I go to Home Depot or any hardware/electrical
supply store and buy bare copper wire! It works and is much, much
cheaper then copper foil. On my plant tables l wrap the legs about two
or three turns, about 1/2 inch gap between, with the bare wire, staple
it to the wood. On my raised bed garden l staple one strand across the
top of the wood. Works like a charm! No need for electricity, big
problem there.