Protection of Earthing Grid from Corrosion

Whatever may be the selection of materials the time will not be responsible for that.

My bother is the fault current may not conducted to the earth properly due to this corrosion.

Bingo! I've been using copper ground rods for about 30 years on my farm for all grounding installations (electric fencing & etc for 112 acres) and have never - that's NEVER had a corrosion problem with them. KISS, people. Use a 6' copper ground probe with non-corrosive clamps/connections, and IF you experience corrosion, I want to know what kind of ground you're pounding it into!

Is the soil acid sulphate? I assume it is. What type of soil do you have? Sandy soil, loam, rock, as all these can cause corrosion and poor earthing results. Is it galvanic corrosion?

If you are concerned, which you obviously are, install additional earth rods. (As sacrificial earths). The earths spikes can be installed in conductive cement and the earth tape, in a cement bound sand mix, (CBS), with a high slump. This mix ratio can be found in UK National Grid standards. Alternately, remove the existing soil, install a better backfill soil in the earthing trenches, (150mm base, compacted and then back filled with the same new soil and compacted again every 100-150mm levels, max). This new back fill will protect the earth tapes but over time the soil will become contaminated with moisture and rain.

At the connections to the earth rods, (if they are fully buried), wrap the conections with Denzil tape and this will assist in keeping out corrosive fluids from the soil, to the connections.

The next alternate is to install an insulated earth wire/cable, to suit your earth faults, the earth spikes installed into conductive cement and the connections protected by an earth pit box, which means it is at ground level and not below the soil. And circulate the earths back to a suitable area with good soil. This will be quite deep and a large area to obtain your earth readings.

You need to determine the soil type first, do a dry test and wet test. Once this is done then the ground could also be chemically treated to neutralise the corrosive effect, but, as stated previously, a routine maintenance check of all earth spike readings would need to be carried out. There are many treatments and fertilizers that will neitralise the soil and help to prevent corrosion. You need to verse costs against copper loss and replacement costs. If it is a new install, simple change the soil in the area or treat it with neutralisers. If existing, treat with a nutraliser, or dig it all up and replace the soil. This is not a cheap quick fix issue.

Aglime has a Ph of 8.2 and is good for treating acid sulphate soil. Just use it carefully.

Check the web for service provider who stabilise soils, there is a lot available, it is your budget that will determine your solution.