Abstract: An anode electrode is disposed to expose in water in a medical waterline, and a cathode is connected to an outer surface cf the waterline electrically conducting to an inner surface of the waterline or exposed in water in the waterline, and by these electrodes, an electric current of an output within the range from 3 to 50 mA is applied to water in the waterline, thereby providing an electric current sterilization method for the medical waterline and water therein, with improved cost effectivity, safety, and sufficient sterilization characteristic.

Abstract: A main anode and a pilot anode are mounted on a coating film of a metal structure, a cathode is mounted on a metal based material of the metal structure, a predetermined voltage is applied from the pilot anode to the metal structure, a magnitude of corrosion protection current of the metal structure is read from a current value of the pilot anode varying with variation of corrosion environment of the metal structure, the application voltage of the main anode is increased or decreased in accordance with the current value, whereby providing a cathodic protection method and apparatus for a metal structure capable of expanding protectable area by a single anode to a maximum without causing over-corrosion protection.