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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
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shasta
155 posts
 
Cincy: You really can't do a free, engineering project via an audio Forum. That's a bit much to expect, both financially and even more importantly, from a liability standpoint. You are very bright, curious, and well spoken, but, respectfully, and I'll buy the first beer - y'all are drifting into a real project. And, respectfully, if we don't know that ground rods come in 10 ft lengths, and that driving one takes a specialized tool, and is the ultimate in apprentice physical labor, and that there are a ton of NEC requirements to be met, well...

Saying that you may want to consider engaging a freelance (not an engineering company) registered electrical engineer to prepare several drawings on what you wish to do. You can verbalize your electrican through it, but, that is always poor practice. That includes an as-build of your entire home system. Expensive, but hand waving a Journeyman electrican will burn up a stupid amount of hours; and here in N. CA, the billing rate will be about $80/hour.

Not a shareholder, employee, sales rep of any mentioned product. The XIT system is a large, hollow ground rod packed w/ trick material. It is vented at the top to absorb ambient humidity, thusly maintaing a very low impedance with the contacting soil throughout the year despite weather conditions. It is used by Honeywell for their DCS (Distributed Control Systems) in their localized Remote Instrument Enclosures handling plant control of digital inputs/outputs and analog signals in the milliamp level. It is installed in at least one Chevron refinery in California.

It also is, possibly, stupid overkill for a residential app., but in this day and age when 6loons is reviewing new-car priced transports/DAC's, I'm lost...

If your curent system is in good condition, and has a measured reasonable impedance, I wouldn't loose sleep on this...
cincy_bob OP
270 posts
 
Shasta, about a month ago, I hired a registered electrical engineer to develop drawings for the modifications to my residential electrical system. What I have been doing in this forum is educating myself so that I can raise the right topics with - and ask the right questions of - my electrical engineer and my electrician.

The service drawings for my system do not contain any detailed specifications for the grounding of the new circuit panel. Without the aid of this forum, I would not have known that there was any alternative to simply grounding the new panel back to the incoming water line that currently serves as the grounding electride for my electric system. And, without any discussion of the topic with my electrician, I am sure he would have opted for this single ground without any discussion and without me being aware of any alternative for a secondary ground. The education Jea48 has provided me regarding the option of installing a secondary outside new earth ground electrode allows me to have an intelligent conversation with my electric professionals that I could not otherwise have even initiated.

Jea48, thanks very much for all the information you have shared. It is very helpful to me and will significantly enhance my ability to communicate with my electrical engineer and electrician.
talon4
185 posts
 
I'd check out www.equitech.com. They're the people into balanced power; however, they also have different articles that can be downloaded via computer. One of these articles is "setting up an a/c ground." I used one 10' 5/8" copper ground rod. If you use two, they need to be separated by at least 8'. As for putting the ground rod into the ground... Use water. Slowly dribble it into the hole that the rod is making, as you plunge it up and down. The pressure of the rod tip--(like a high heel shoe-pressure per square inch, ouch!), and the water at the hole's developing surface will cut through the dirt in no time. Be careful with that project. I've read multiple grounds can be dangerous. Hope all this helps. Good Listening!
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