Abstract: A panel can be assembled with similar panels to form a security fence or other barrier. The panel carries at least one wire connected, in use, to a source of high tension impulse electrical voltage. The wire is housed to prevent contact therewith except where penetration of the housing occurs. Panels can be positioned on or above the top of an existing fence or other barrier. An electric fence kit is also provided for erection of an electric fence in an existing fence. The kit includes a plurality of wires to be electrified, at least two posts, and mounting structure for mounting the posts in the existing fence and a plurality of guides for each post. Each guide is for guiding one of the wires, in use.