In a pipe-to-soil potential profile, how is the voltmeter connected?

In a pipe-to-soil potential measurement, the correct method of connecting the voltmeter is to attach the positive lead to the pipe and the negative lead to the electrolyte, typically the soil. This configuration enables the voltmeter to measure the potential difference between the metallic structure, which is the pipe, and the surrounding environment, which is represented by the electrolyte or soil.

By connecting the positive lead to the pipe, the voltmeter measures the electric potential at the pipe's surface, while the negative lead connected to the electrolyte provides a reference point for that measurement. This configuration is essential to accurately assess the corrosion protection status provided by cathodic protection systems since it reflects the potential that the pipe experiences relative to the surrounding earth, indicating whether it is adequately protected against corrosion.

In other configurations, such as connecting the negative lead to the pipe or attaching the positive lead to the ground, the data obtained would not accurately indicate the potential difference pertinent to assessing the cathodic protection effectiveness. Therefore, the chosen method is critical for correctly evaluating corrosion control measures and ensuring accurate readings during testing.