Captain Ramsey, when he assigns the platoon the task of getting over the "electrified" fence is asked by Jones if there is really any electricity in it. Ramsay replies that there is just enough to remind them that its there. However, when the platoon tries to surmount it, it sets fire to their ladder, and several other items. These items would be non-conductive in most cases, so there must be several thousand volts actually coursing through the fence.