Cathodic Protection Tester Practice Exam

Metallic shorts to a structure with cathodic protection will normally result in what?

1. Higher circuit resistance, lower current output

2. Lower circuit resistance, higher current output

3. Loss of electrical isolation

4. Increased anode life

The correct answer is: Lower circuit resistance, higher current output

When metallic shorts occur to a structure that is protected by cathodic protection, they create a direct conductive pathway between the structure and the surrounding electrolyte. This leads to a significant reduction in circuit resistance because the electrical path through the short is typically much lower in resistance compared to the intended path of current flow through the cathodic protection system. As resistance decreases, Ohm's Law dictates that the current output from the cathodic protection system increases, as the same voltage will now push more current through a lower resistance path. This results in a higher current output, which could potentially be harmful if the system is not designed to handle such conditions. Increased current output can intensify the protective effect on the structure but can also lead to issues such as excessive anode consumption. Other choices do not align with this understanding as a metallic short would not typically lead to higher circuit resistance or electrical isolation; rather, it disrupts the intended protective current distribution. An increase in current output does not contribute positively to anode life, as more current generally results in faster anode wear rather than increased longevity.