What happens to current output when there is a metallic short with cathodic protection?

When there is a metallic short in a cathodic protection system, the current output typically increases. This occurs because a metallic short creates a lower resistance path for the current to travel through. As a result, more current flows to the area that is experiencing corrosion. The cathodic protection system is designed to provide protection by supplying sufficient current to mitigate corrosion; therefore, when a short circuit happens, it effectively reduces the impedance in the circuit, leading to a rise in the current output.

In terms of other options: if the current output were to decrease, it would imply that there is an increase in resistance or a break in the circuit, which is contrary to what occurs with a short. Fluctuations in current output would suggest an unstable current flow, which does not align with the consistent increased flow expected due to the short. Stability in current output would also suggest that no significant changes in the circuit are present, which does not accurately depict the impact of a metallic short. Thus, an increase in current output is the most appropriate and expected response in this scenario.