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Installing an AC Grounding System, Need Advice

Later this week, my electician will begin work on my electric project, which will involve the installation of a 7.5kVA isolation transformer that will be fed from a separate meter tap. The isolation transformer will be installed in front of a new dedicated circuit panel that will house the dedicated circuits that will feed my listening room. All the dedicated circuits will be fed from the same side of the bar in the new panel in order to maintain consistent phase.

As Sean has advised in a separate thread, I know it is important that I check - and upgrade as necessary - the ground for my AC system. (My house was built in the late 1950s, and, from the looks of things, not much has been done since that time to upgrade the electric service. So I am nearly certain that I will find the grounding system leaves much to be desired.) I also know from discussion in various other threads that it is important for the entire electrical system in my house to share a common ground. So I expect that I will need to upgrade the grounding system into my main circuit panel and then tie the isolation transformer and the new dedicated panel back to that same grounding system.

The work on my house is being performed by a qualified electrician, but, as I have noted in other threads, I would like advice on the audiophile details that can make a difference in the sound (in this case, the noise floor) of my system. Perhaps I should also mention that my plan involves installing a separate dedicated circuit for each of my seven components. Given that this sort of a set-up is more prone to ground loops, I am interested in advice regarding how to avoid them with this set-up.

With that as background, would any of the resident experts be willing to share with me the details of how to install a high quality grounding system for my AC power? I would appreciate as much detail as possible regarding the materials to use as well as installation advice.

I have read some advice in other threads recommending two separate copper grounding rods driven into the ground relatively close to each other with a weather-proofed connection between the two rods that is, in turn connected to the electrical system. I have also seen some advice that I believe involves wiring one of these connected ground rods to the main house circuit panel and the other connected ground rod to the audio portion of the system (i.e., in my case, the isolation transformer and the new dedicated circuit panel). Please let me know if this is headed in the right direction and, if so, please help me to fill in some details (dimensions of the copper, advice on how to drive it into the ground without mangling it, distance between the redundant rods, any other details you see fit).

As always, thanks for your help and patience.
cincy_bob
talon4
185 posts
 
Jea48, the "water method" that you commented about is the method that was used by my electrician to drive the rod. The power was disconnected and the ground wire hadn't been connected to the rod yet. My electrician works for the one of the biggest electrical contractors in town. Are you saying that what he did wasn't legal? I've heard others use this method in my area as well.
jea48
2,944 posts
 
Slv, thats the best way to do it. For those of you who want to do it yourself and do not have access to an electric hammer, you can use a steel fence post pole driver. It will get you within about 30" from the ground. dig around the rod about 6" deep, and you can drive another 6". That last 2' you will need to use a sledge hammer. Aim carefully.
jea48
2,944 posts
 
When the rod is driven into the earth it gives the tightest friction fit possible. Using water as a lubricate you are boring a hole for the rod to travel through. As the water migrates into the soil and through evaporation,as time passes, the soil around the rod tends to shrink away from the rod. Does it make that big of a difference? ? It is a lot easier to install with water. And when you drive a rod dry you won`t know if you hit something important, like a Phone line, Gas line, Power line, Water line, Sewer line, you get the idea. The water method is safer. Course you could call for locations. But that won`t cover every thing either. If you do it your self call for locations.
8' distance between rods is better than 6'. NEC just says that is the min. The power company in my area requires 2-5/8 X 8' ground rods driven 8'-4" deep 8' apart 3' out from the foundation of the house for the electrical service grounding electrode. The general rule of thumb is the min distance apart should not be less than the length or the rod used.
How deep can a ground rod be driven? If you go to an Electrical Wholesale House you can buy ground rods with threaded ends. As you drive the rod you can use a couping and connect another and so on. If you live in an area where soil moisture is low this works well generally.
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