Abstract: A battery jumper cable assembly for preventing electrical sparking when a pair of batteries are connected together. The battery cable assembly includes a ground wire and a power wire with a switch assembly being connected at a location along the length of the power wire. The switch assembly includes a housing for a slidable switch element having an electrically conductive contact plate. The switch element is biased toward a normally open or off position by a spring. The power wire includes spaced apart contacts within the housing and the switch contact plate is movable to bridge the gap between the contacts. An electromagnet is mounted within the housing in alignment with the slidable switch element, and the electromagnet is electrically connected to the ground wire and to a contact element within the switch housing.