Earth resistance is set by the soil resistivity and the electrode, so you lower it by reaching better soil or enlarging the electrode contact. The proven methods are: drive the electrode deeper into moist soil, add more electrodes in parallel, surround the electrode with earth-enhancing compound, or use a conductive-concrete electrode.
The methods, in order of effect
- Go deeper - a longer rod into moist, stable soil gives the biggest single drop.
- Add rods in parallel, spaced at least their length apart.
- Pack earth-enhancing compound around the electrode to cut contact resistance.
- Use a conductive-concrete electrode where soil is rocky or high-resistivity.
- Keep the pit moist - a watering funnel helps in dry seasons.
