The Electric Fence is the same as a Fence, but is blue and when you are trying to cut it, it will electrocute you. (You will take 20 damage, and be sent to infirmary if knocked out.) They also electrify the ground tiles beneath them, which means that attempting to dig a tunnel through these tiles will shock the player. Note that the tiles below an electric fence are not destroyed by cutting tools, but are simply dug through like any other ground tile.
You can safely cut an electric fence, or dig under it, if you disable the Generator. It is found in Stalag Flucht, San Pancho, Jungle Compound, HMP Irongate and in some prisons of The Escapists 2, including the DLC The Glorious Regime.
In The Escapists 2, electric fences spark and shock you if you get too close.