Abstract: Detection of events, e.g. liquid leaks and other changes in varibles. The event causes two conductors to become electrically connected, and thus creating a system in which the connection point can be located by measuring the potential drop from one end of one of the conductors (called the locating member) to the connection point. Preferably a fixed current flows through the connection, so that the result is independent of the resistance of the connection. The locating member can be a continuous resistive wire, preferably coated with a conductive polymer; such a locating member can form part of a sensor cable in which the elongate components of the circuit are in a wrapped configuration, or part of a cable in which the conductors are separated by a member shaped to prevent capillary action of a liquid from connecting the conductors. Alternatively the locating member comprises a plurality of discrete resistors.

Abstract: An apparatus for detecting the occurrence of an event, e.g. the presence of a liquid leak. The apparatus includes an elongate flexible core consisting of elongate elements which are twisted together. The elongate elements comprise first and second sensing members, which each have an electrically conductive outer surface and are physically separated from one another, and at least two elongate insulating members. These elongate elements are covered by a flexible braid which exerts a compressive force on the core. In one aspect of the invention, the flexible braid undergoes a reversible change in appearance when exposed to electrolyte, indicating the location of a leak.