A device and method for attenuating high frequency signals on a power line carrying power is provided. In one embodiment the device may include a toroid shaped core formed of magnetically permeable material and having an inner surface to be disposed substantially around the entire circumference of the power line and a winding formed of a conductor that encircles the toroid. The conductor may include a first spiral coil comprised of a plurality of insulated loops such as concentric loops. The first coil is configured to act as an impedance to high frequency signals traversing the conductor and to allow signals below one hundred hertz to traverse the conductor substantially unimpeded to thereby prevent saturation of the core by the power carried by the power line.