I've run a dedicated ground on a separate line in my system. Big help! It was done all inside the ac box and wall, not ouside via cheater plugs. sounds kind of like the same concept...
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Make sure your "Reference ground rod" Ties to your service ground or is no more than six feet away from your service as not to create two potential references points to ground.
I have installed such a grounding system with the exception of lifting the ground at the equipment. IMO if everything is isolated back to the Iso ground rod and you install an isolated grounding recptacle (I.G.) why bother. This system did in fact pass an electrical inspection without connecting the two ground rods together. They were about four feet apart.
Glen brings up a VERY good point. If you are going to isolate the grounds between your audio gear and the rest of your houe, you DO create a serious potential for danger / equipment damage if lightning or severe surges were to come in through your mains. Don't overlook such a thing happening, as i DO know people that this has happened to. One of the "regulars" here recently lost a several thousand dollar amp due to lightning damage.
Since everything in your house would be tied into a common feed line outside, the energy would seek the lowest resistance path to ground. The electrons will not differentiate between WHICH ground it goes. If your audio system ground is shorter and offers lower resistance, ALL or nearly all of that energy would be dissipated by it. The key ( in terms of safety ) is to have seperate grounds, yet grounds that are of equal potential. This would then share the load and minimize damage to any specific circuit or the components connected to that circuit.
To do this, the ground rods must be in close proximity to each other. You might be surprised at the difference in Earth conductivity, even within a short distance of 10'- 20' or so. The closer that you can get them together, the better off you'll be. You also want to space them a short distance from the foundation of the house. This exposes the rod to more Earth for greater conductivity. Otherwise, the distance from the rod to the concrete foundation will limit conductivity. This may give you a three sided ( or even two sided if planted in the corner of an alcove ) ground connection.
Keep in mind that different areas also have different levels of ground conductivity. With that in mind, the longer the rod that you use, the greater your chances of getting a good ground. One should not rely on a ground rod of shorter than 6' ( at the minimum ). While i know that Rat Shack and many other places sell 4' rods, that may not get you below what is called the "frost line". As such, you would end up with a wire connected to a rod sitting in the ground, but not grounded. Be careful when driving LONG ground rods into the earth though, as you don't want to pierce or puncture existing cabling from phones, cable tv, electricity, water or gas lines, etc... Most utility companies offer a free service to show you where you have utility lines coming into your house, making it safer to dig around your house. Sean