What is the role of a reference electrode in corrosion potential measurements?

• A. Delivers current to the structure
• B. Measures ambient humidity
• C. Provides a stable reference potential to compare against the structure's potential for CP assessment
• D. Plays no role

Answer: (C)

The essential idea is to have a stable reference point for interpreting the metal’s electrical potential. A reference electrode provides a known, steady potential that does not depend on the current in the circuit, so you can compare the structure’s potential against this fixed value. By measuring the voltage between the metal and the reference electrode, you obtain the corrosion potential and can judge whether the structure is near its natural corrosion tendency or sufficiently polarized by cathodic protection. The reference electrode itself does not deliver current to the structure—that role belongs to the power source and anodes in a CP system—nor does it measure humidity. So its job is to supply a stable reference potential for CP assessment.