Abstract: A leak sensing cable for a leak detector having an impedance sensor operable to measure changes in impedance along a sensing circuit. The leak sensing cable comprises: an inner core, having a first conductive thread electrically connected to the sensing circuit; an inner sheath, coaxially located around the inner core, the inner core being comprised of a permeable, non-conductive material; an outer sheath, coaxially located around the inner sheath, the outer sheath comprising a permeable braided material and having a second conductive thread woven into the permeable braided material, the second conductive thread being electrically connected to the sensing circuit. The first conductive thread is substantially electrically isolated from the second conductive thread when the leak sensing cable is dry and less electrically isolated from the second conductive thread when the leak sensing cable becomes wet.