Temperature - controlled cable runs straight along pipe and valves, held in place by application tape and plugs into grounded electrical outlet. Keeps water flowing to -40. Pipe requires 1/2" non-flammable insulation such as fiberglass. For plastic pipe, its recommended wrapping pipe with aluminum foil before cable installation. The traditional resistance cable produces a fixed amount of heat based on the electrical line feed. It comes with a built-in thermostat that switches the flow of electricity on and off based on temperature. 120 volts. 7 watts per foot. CSA listed.