What protective measure involves low voltage current that concentrates corrosion on a sacrificial anode?

The correct answer is cathodic protection. This method is used to prevent corrosion of metal surfaces, particularly in environments where they are exposed to moisture and other corrosive elements. In cathodic protection systems, a low voltage electrical current is applied to the metal structure, which creates an electrochemical reaction that protects the structure from corrosion.

The key aspect of cathodic protection is the use of sacrificial anodes, which are typically made of more easily corroded metals such as zinc or magnesium. These anodes are connected to the metal structure, and as the system operates, the sacrificial anodes corrode instead of the protected metal. This mechanism effectively redirects the harmful electrochemical processes that lead to corrosion away from the structural metal.

Understanding this process is crucial for water operators, as it directly relates to maintaining the integrity of pipelines and storage tanks that are essential for water supply systems. The other options, while related to corrosion and metal protection, do not involve the same principles of electrochemical protection that characterize cathodic protection.