An easy way to tell CF Walls from CF Cables

I made a discovery just now: It is known that as of 1.70, CF can cover a cable, creating a "CF cable block" that looks like a CF wall but can transmit EU. But, while trying to break normal CF walls produces the stone-breaking sound, trying to break CF Cables produces the wool-breaking sound! Very useful when trying to remember where your EV wiring was placed