AMPP Cathodic Protection Technician (CP2) Practice Exam

When using coupons to measure the polarized potential of a structure, there does not always have to be a discrepancy between the potential readings of the coupon and that of the structure. Coupons are often installed in close proximity to the structure they are meant to protect, and ideally, they should be representative of the same corrosion environment.

In many cases, the readings obtained from the coupon should closely approximate the polarized potential of the structure because they are subjected to the same external conditions such as soil resistivity, moisture content, and the presence of corrosive agents. If the coupons and the structure are maintained under similar conditions, the potential differences can be minimized.

However, it's worth noting that factors like slight differences in electrical contact, the physical separation of the coupon from the structure, or variations in local electrochemical behavior can occasionally cause variations in readings. But as a general principle, discrepancies are not a given and it is entirely possible for the potentials to align closely under appropriate conditions.