.. from the book "Grounding: answers to questions"
Why copper-bonded ground electrodes serve much longer than of ordinary black steel?
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I'll speak in a roundabout way.
Electrochemical corrosion takes place at the contact of two metals with a significant difference of oxidation-reduction potentials + in the presence of an electrolyte (moisture).
For example, copper and aluminum, steel and copper, steel and zinc - in wet soil or covered with condensation. Moreover, one metal acts as a reducing agent / donor and the other as an oxidant. In "simple Russian" it means that one metal will be rapidly oxidized (the speed can be increased by an order of magnitude in comparison with the pure metal corrosion), and the other will be almost completely whole until the first metal is not corroded.
In the pair "zinc-steel" the reducing agent / donor = zinc. When it corrodes - steel will begin to corrode. In the pair "copper - steel" the reducing agent / donor = steel, oxidant = copper. While the steel completely turns into, nothing will happen to copper. Wherein if you close steel in the pair "copper-steel" from the electrolyte, the electrochemical corrosion will be completely stopped.
Using galvanized electrodes you increase the service life of the electrodes, but this increase is significant only if you use a very large mass of zinc (large thickness of zinc coating on steel). Hot-dip galvanizing js widely used, it is affordable, provides a thickness of 20-100 microns. It's not enough.
So if you "want a ground electrode" with a long service life, the choice is either after "galvanization" with a thick layer of zinc (about 1000 rubles per square meter) or copper-bonded pins (about 375 rubles per meter). Copper plating is more affordable than thick galvanization at a comparable service life (up to 100 years).
It should be noted that copper-bonded ground electrodes serve for a long time ONLY in the presence of high-quality coating. You can read more about inspections / testing of the surface on a separate page "ground rod".
P.S. An important point for copper bonded steel is copper deposition technology. There are steel ground rods, covered with copper foil met on the market. Such coating peels off with pieces during installation, providing access to oxygen and moisture to the pair "copper - steel". Rots 3 times quicker than simple black steel. And since it is hard to visually identify this place (since the ground electrode is deep in the ground) - you can exactly determine the quality and durability of such a "ground electrode". It is forgettable! So be careful when choosing a vendor. It is easier to trust reliable and proven ones. ZANDZ, for example :-)
Useful materials:
- Modular grounding
- Grounding in a private house
- Grounding in permafrost
- Grounding in rocky soil
- Consultations on the selection, design and installation of grounding and lightning protection systems
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