A ground driven into rock or buried in dry gravel isn't going to be of much use. Typically electrodes are buried in a mixture of bentonite and gypsum, which is

A ground driven into rock or buried in dry gravel isn't going to be of much use. Typically electrodes are buried in a mixture of bentonite and gypsum, which is pH neutral and provides low resistance. There are also chemical (salt) earth fills which work well but require thicker copper electrodes to deal with corrosion. Various conductor arrangements are used, but in shallow trenches there is always the problem of the wires being cut. A radial or cartesian mesh burial over a larger area would be typical. You can buy electrical mesh and ground enhancement fill for this purpose. Note that you still need it to be below the frost layer in your region -- which varies from 15cm (California) to 300cm (Canada) depending. An earth connected via a distant cable isn't going to be effective against lightning (transients are high frequency and hence conductivity is constrained by the skin effect, and long wires have high inductance even if they have low DC impedance), and additionally is poor practice as it is more lightly to be cut without someone knowing in the future. I doubt any EE would approve it when other methods are available. https://blog.nvent.com/erico/erico-what-is-soil-resistivity-and-how-does-it-affect-grounding/ https://blog.nvent.com/erico/erico-what-is-soil-resistivity-... Cf IEEE 80 & 81