CATHODIC PROTECTION AND ELECTRICAL RACK GROUNDING
CATHODIC PROTECTION AND ELECTRICAL RACK GROUNDING
(OP)
Cathodic Protection and Electrical Distrubution Grounding
Our package provides an installation of the Electrical Rack for feeding a pipeline controls and instrumentation.
Electrical Rack plus the part of Pipeline ( above ground level) will be protected with a fence and grounded.
We are informed that galvanized steel ground rods have to be used in lieu of copper ground rods because of future cathodic protection systems in that area, what has to reduce a potential difference.
Is it true ? Please, comments !
Our package provides an installation of the Electrical Rack for feeding a pipeline controls and instrumentation.
Electrical Rack plus the part of Pipeline ( above ground level) will be protected with a fence and grounded.
We are informed that galvanized steel ground rods have to be used in lieu of copper ground rods because of future cathodic protection systems in that area, what has to reduce a potential difference.
Is it true ? Please, comments !






RE: CATHODIC PROTECTION AND ELECTRICAL RACK GROUNDING
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If we learn from our mistakes,
I'm getting a great education!
RE: CATHODIC PROTECTION AND ELECTRICAL RACK GROUNDING
Principle: Galvanic corrosion occurs when a burried electrode of one kind of metal is connected to another kind of buried metal (connection above or below ground) and the soil contains electrodes in a moist enviroment.
The table gives a restricted list of metals which are used in electrical contacts in one form or another. The aluminium end of the series is known as the "active" end and the gold end of the series as the "noble' end.
Metal Standard electrode potential at 25°C
Aluminium -1.67
Zinc -0.76
Mild Steel -0.44
Cadmium -0.40
Stainless Steel(active) -0.30
Nickel -0.25
Tin -0.14
Lead -0.13
Copper +0.34
Stainless Steel(passive) +0.50
Silver +0.80
Carbon +0.81
Mercury +0.85
Platinum +1.20
Gold +1.70
The less noble of the two metals will become the anode and will corrode. For instance, in a sell using zinc and copper, negative ions in the soil will flow from the copper (cathode) towards the zinc (anode), and the latter will corrode
Hence if metal of the earth electrode is more noble than other metals buried in the ground (e.g. copper-plated earth rods in the vicinity of steel foundations, steel reinforcing in concrete foundations, cast iron pipes, zinc coatings on galvanized pipes or steel armouring of cables), galvanic corrosion of the steel and zinc can occur.
The wider apart the metals are in series, the higher the potential difference and hence the greater the galvanic corrosion.
Loss of some typical metals when they are anodic is:
Lead :33 kg/ampere-year
Zinc :11 kg/ampere-year
Iron (steel) :9.1 kg/ampere-year
Regards
Ralph
RE: CATHODIC PROTECTION AND ELECTRICAL RACK GROUNDING
RE: CATHODIC PROTECTION AND ELECTRICAL RACK GROUNDING
If you have Cu ground rods and by some chance its potential is higher than the anode bed, either due to location or physical conditiions, then the Cu rod will start decaying.
On a side note any metal in between the anode and cathode shall decay because it would act as a cathode for the anode bed but at the same time would also act as anode for the pipeline. I know this isn't the case here with the Cu rod.
In nut shell its recommended to have steel electrodes for the grounding system.
Sarg