Cathodic Protection Tester Practice Exam

What is a limitation of using ohmmeters in corrosion work?

1. Limited to high voltage applications

2. They use alternating current

3. Limited use in checking circuit continuity

4. Limited use in measuring resistance between structures in an electrolyte

The correct answer is: Limited use in measuring resistance between structures in an electrolyte

The correct response highlights a significant limitation of ohmmeters in the context of corrosion work: the challenge of accurately measuring resistance between structures in an electrolyte. When dealing with corrosion testing, particularly in environments where metals are submerged in electrolytes (like water or soil), factors such as the presence of stray currents, variations in electrolyte composition, and sediment layers can significantly affect the readings produced by an ohmmeter. In practice, ohmmeters are not able to account for the complex interactions happening in these environments, which can lead to misleading conclusions about the integrity of protective measures or the condition of the metal structures being assessed. For accurate readings in such scenarios, specialized methods, such as using potential measurements or specialized corrosion monitoring equipment, are preferable, as they can better account for these complexities. The other options address limitations that do not directly pertain to the specific environment of corrosion work. For instance, the mention of high voltage applications or alternating current typically pertains to the suitability of the equipment itself rather than its application in corrosive environments. Similarly, while checking circuit continuity is important, it does not directly relate to the measurement challenges posed by electrolyte interactions in corrosion applications.