Which type of anode system is very susceptible to stray current?

The impressed current cathodic protection (ICCP) system is indeed very susceptible to stray current. This susceptibility arises due to the way ICCP systems function. In these systems, an external power source is used to drive current through the anodes and into the electrolyte (e.g., soil, water) to provide corrosion protection to a cathodic structure.

Since the current is actively imposed onto the structure, any stray currents in the vicinity can interfere with the effectiveness of the ICCP system. If there are stray currents from other sources, such as nearby electrical installations or industrial activities, they can create an unintended pathway for current, which can either reduce the protective current effectively reaching the intended structure or lead to increased corrosion in other areas due to imbalanced current flow. Thus, the risks associated with stray currents are particularly pronounced in ICCP systems due to their reliance on an external power source to manage the current flow for cathodic protection.

In contrast, galvanic anodes operate based on electrochemical reactions without an external power source and are therefore less impacted by stray current effects.