If a metal structure has a very low D.C. current going to the ground, what does it indicate?

A very low D.C. current flowing to the ground from a metal structure suggests that there may be a form of corrosion process occurring, which can occur due to electrochemical reactions. The presence of a low current indicates that the metal structure is not effectively diverting any oxidation or corrosion potential, which is sometimes due to insufficient protection against corrosion.

Implementing a sacrificial anode can be an effective way to address corrosion. A sacrificial anode is a piece of metal that is more reactive than the metal of the structure. It provides a pathway for the corrosion process to occur on itself rather than on the more important structural metal. When the current is low, it shows that the intended protective measures (like sacrificial anodes or cathodic protection) may not be adequate, and adding a sacrificial anode would help to redirect the corrosion away from the structure.

In contrast, proper insulation would lead to little or no current flow, indicating there might either be a good insulation system or that the structure is inherently insulated from environmental elements that could cause corrosion. If the structure is well grounded, one would expect a reliable D.C. current making it less susceptible to corrosion-related issues. A claim of no risk of corrosion would be unfounded if a