Mother earth’s ground connection (example ground rod/s) main purpose is for lightning protection.
You can drive as many ground rods as you want as long as they are all tied together and one wire is extended and connected to the main electrical service neutral conductor. The NEC considers all the connected together ground rods as one grounding electrode.
Again, The earth does not possess some magical mystical power that sucks nasties from an audio system.
Grounding Myths
From Henry W. Ott’s book "Electromagnetic Compatibility Engineering"
3.1.7 Grounding Myths
More myths exist relating to the field of grounding than any other area of electrical engineering. The more common of these are as follows:
1. The earth is a low-impedance path for ground current. False, the impedance of the earth is orders of magnitude greater than the impedance of a copper conductor.
2. The earth is an equipotential. False, this is clearly not true by the result of (1 above).
3. The impedance of a conductor is determined by its resistance. False, what happened to the concept of inductive reactance?
4. To operate with low noise, a circuit or system must be connected to an earth ground. False, because airplanes, satellites, cars and battery powered laptop computers all operate fine without a ground connection. As a mater of fact, an earth ground is more likely to be the cause of noise problem. More electronic system noise problems are resolved by removing (or isolating) a circuit from earth ground than by connecting it to earth ground.
5. To reduce noise, an electronic system should be connected to a separate “quiet ground” by using a separate, isolated ground rod. False, in addition to being untrue, this approach is dangerous and violates the requirements of the NEC (electrical code/rules).
6. An earth ground is unidirectional, with current only flowing into the ground. False, because current must flow in loops, any current that flows into the ground must also flow out of the ground somewhere else.
7. An isolated AC power receptacle is not grounded. False, the term “isolated” refers only to the method by which a receptacle is grounded, not if it is grounded.
8. A system designer can name ground conductors by the type of the current that they should carry (i.e., signal, power, lightning, digital, analog, quiet, noisy, etc.), and the electrons will comply and only flow in the appropriately designated conductors. Obviously false."
Henry W. Ott
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