2017 NEC 250.6(E) Isolation of Objectionable Direct-Current Ground Currents.

[Fred B]

Was looking for something else and just noticed this section and curious as to its application. Can someone give an example of when and how this condition would present itself that would require remediation? Relavent in normal residential? Is this or can this DC current generate from the galvanic process of a sacraficial cathode in water heater tank, and then present on the EGC and noise on the AC power systems? Just not sure of what this section is referring to and why.
Most every reference online was related to marine (boat), or pipeline / tank protection from rust.

 

[Greentagger]

Seems as though it’s actually a low current induced purposely on pipes to prevent galvanic corrosion. Pipelines ,etc.?

 

[tortuga]

Here is a link to some old but still relevant info, its a great system for preserving old steel buildings:

https://www.ecmag.com/section/codes-standards/tricky-subject

Cathodic Protection

Chris Wozencroft outlines how cathodic protection can negate corrosion in historic buildings, considering its effectiveness in combating Regent Street Disease in particular.

buildingconservation.com