Interference Testing Guidelines for Impressed Current Cathodic Protection Systems
For new and existing structures
Form Submissions made to: Secretary.SAEC@gmail.com
The South Australian Electrolysis Committee recommends the following method as a guide to assess whether a cathodic protection system is interfering with or may potentially cause corrosion to another buried structure.
It is recommended that an ‘Advice of a new Cathodic Protection Installation or change to an existing Cathodic Protection System’ (see Form A), including plan showing location details, be completed prior to installation or upgrading of any system. A copy should be forwarded to the committee and to all structure owners in the vicinity who may be affected by the installation.
To test for interference, the output of the cathodic protection system in question is switched on and off cyclically at a known rate. Any consequent fluctuations in potential on structures under test are recorded on ‘Results of Interference Testing’ (see Form B) and a copy of the results should be forwarded to the South Australian Electrolysis Committee. Testing should be performed by suitably qualified personnel.
Acceptable potential shifts of the structure under test relative to the potential of the structure, when the cathodic protection is off, should be within the following limits:
- 20 mV anodic or positive swing
- 200 mV cathodic or negative swing
Cathodic protection systems which interfere with a secondary structure, outside the above stated limits, should not be operated as corrosion damage of the structure may occur. Larger fluctuations may be tolerated, but is subject to negotiation and agreement between affected parties.
Further information can be obtained from:
“AS2832 Guide to cathodic protection of metals:"
- Part 1 - Pipes, Cables and Ducts
- Part 2 - Compact buried structures
- Part 3 - Fixed Immersed Structures
- Part 4 - Internal Surfaces
- Part 5 - Steel in Concrete Structures
Persons should also be aware of the requirements for cathodic protection systems in South Australia as required by Part 5 of regulations under the “Electricity Act 1996”.
The South Australian Electrolysis Committee should be contacted to ascertain the contact person within each utility and may assist in coordinating testing and interpretation of results.
