A reference potential reading that exceeds -1100 mV indicates what condition?

A reference potential reading that exceeds -1100 mV indicates excessive cathodic protection. Cathodic protection is used to prevent corrosion, especially in submerged or buried metal structures, by driving the potential of the metal to a level where corrosion is minimized. The standard reference points for acceptable cathodic protection levels typically range from -850 mV to -1100 mV, depending on the specific environment and metals involved.

When the potential reading exceeds -1100 mV, it signals that the metal surface is excessively polarized, which means that it is receiving too much negative voltage. This can lead to a condition known as hydrogen evolution corrosion, where excessive negative charge can drive hydrogen ions to form hydrogen gas at the cathode surface. This can weaken the protective barrier and lead to potential damage to the structure.

In summary, a reading greater than -1100 mV indicates an overactive cathodic protection system, which can unintentionally create more issues than it resolves, affirming that the condition is indeed one of excessive cathodic protection.