What are often used to check the effectiveness of CP and made of the same metal as the structure they are connected to?

Coupons are important tools in the evaluation of cathodic protection (CP) systems, as they are made from the same metal as the structures they are connected to. This similarity allows for a direct assessment of how well the cathodic protection is functioning in preventing corrosion on the actual structure material. When coupons are exposed to the same environmental conditions and cathodic protection applied to the structure, they can provide valuable data on the effectiveness of the CP system by measuring corrosion rates over time. Additionally, because they are tested under real conditions, the results can reflect the practical performance of the CP system, enabling adjustments or maintenance to be planned effectively.

Other methods, such as half cells and line locators, serve different purposes within the context of corrosion management and monitoring, and they may not provide a direct measure of the cathodic protection's effectiveness. Current interrupters are primarily used during testing to assess current flow and distribution but do not directly correlate with the material to which they are connected like coupons do. Thus, coupons serve a crucial role in both the assessment and verification of CP efficacy, grounding their use in practical applications.