In the past I believe that coke has been used (the solid fuel, not the soft drink) I think that coke was favoured if the earth connection was expected to carry significant current in normal operation, rather than just leakage currents and the odd fault current.

Earth connections for single wire earth return power circuits, earth connection for cathodic protection systems. I think that some of the HVDC interconnectors use coke beds in the earthing system. Under normal conditions, two cables are used, one for positive and the other for negative. If one cable is faulty, operation at half power is possible by use of the sound cable and an earth return.

Ignoring the fact that this is not in English, this video shows the installation of a charcoal and salt enhanced rod, in a dry place.

The pictures make the technique clear enough.

https://www.youtube.com/watch?v=LcFNHPkTuQ0

I note with some amusement the 'bulb in series ' test for a nice low electrode resistance about 7 mins in . Not to be repeated in any country with a health and safety policy.... Still, at least he is not bare-foot.

Mike

Ignoring the fact that this is not in English, this video shows the installation of a charcoal and salt enhanced rod, in a dry place.

The pictures make the technique clear enough.

https://www.youtube.com/watch?v=LcFNHPkTuQ0

I note with some amusement the 'bulb in series ' test for a nice low electrode resistance about 7 mins in . Not to be repeated in any country with a health and safety policy.... Still, at least he is not bare-foot.

Mike