When we walk in headlands right by the ocean it us usually through cow pastures (Asturian cows like ocean views) so we have to cross fences. We saw some barbed wire fences in Basque Country but in Asturias they are usually single wire electric fences. Some are clearly live, some ambiguous, and some are clearly fake. I guess the cows learn not to touch them and so the fake ones work.
Usually we have to go over steps or a ladder to cross on fence, sometimes a narrow zig-zag that a cow would not fit through. A few days ago we had to cross a wire and then a ladder. I went underneath, scraping it with my backpack and getting my hands damp from the grass. The fence was an ambiguous one so I decided to lift it up so Wynette could go underneath. Zap, it was not fake. The shock was very small though, like something you would get from a 9-volt battery. I remember getting shocked a few times with batteries as a kid doing electricity things. It is hard to believe such a mild shock would deter a cow but maybe it startles them and they avoid it. I guess cows are not big in the cogitation department.