Isolation Transformers

Bash in sufficient earth rods, and connect them together so as to achieve an earth resistance of less than 1 ohm. Local soil conditions will determine the number to be bashed in.

There is no equation for this, as such.

PWSlack is right. Even though there is a lot of research, equations, etc., on the subject, all it gives is a best guess because there are just too many variables. In the end, you still have to test and augment your system as necessary.

Drive multiple earth rods and connect them using a buried copper mesh or network of bare copper radials. The rods should be as widely spaced as practical so that the network covers as large an area as possible.

Low-frequency (VLF and ULF) antenna systems use an extensive grounding system to achieve as minimal earth resistance as possible. High-power navigation transmitters such as Omega (now defunct), LORAN transmitters, and other very-low-frequency systems have grounding networks that cover hundreds of acres in some cases, but especially for the lower-frequency transmitters.

This link may be helpful: Ground Systems

Books on antenna systems can be especially helpful here. Your application may have nothing to do with radio, but the same techniques apply. Check out Amazon.com, for example. If you also have access to the electronic journals hosted by a university library, you can gain a wealth of information covering this subject. IEEE Spectrum, for example, has over a million documents covering all aspects of electrical and electronic engineering. Definitely consult this resource if you have such access.

Hope this has been helpful!

-e

Why 1 ohm? What is the purpose of the ground system?