Running dedicated AC mains .... need advice ....

I agree with all of the excellent cautionary statements that have been made. I want to clarify that the suggestions in my previous post (the third post in this thread) did not mean to suggest anything contrary to these cautions.

I assume that there is and will continue to be a bond between ac neutral, safety ground, and earth ground at the main entrance of power into the house, near the breaker panel. For all existing runs, and for the new ones that may be added. The earth ground is essential for lightning protection, and the bonding of ac neutral and safety ground at that physical location is essential for effective circuit breaker operation, as the paper Jea48 linked to makes clear. And, yes, it seems likely that not having outlet receptacles may be a code violation.

But to restate the point I was trying to make: The downside of having dedicated runs to different parts of the system is increased voltage differential between the chassis of the different components, particularly at high frequencies, which can result in noise currents flowing through the same cable shields as signal return currents, thereby effectively summing the noise into the signal (the very thing that having multiple ac runs is intended to improve).

Connecting the grounds of the different runs together, near the system, will minimize those voltage differences. Jea may very well be correct that tying that local system ground to an earth rod will not accomplish anything, but I don't envision that it would have any negative effects either (in terms of either safety or performance).

A better approach all around, though, may be to utilize isolation transformers, as described by Zargon in this thread:

http://forum.audiogon.com/cgi-bin/fr.pl?htech&1228780109

Regards,
-- Al

The earth shall not be considered as an effective ground-fault current path.
From 2005 NEC 250.4 (A) 5

The earth does not have some magical mystical power that sucks AC noise from our audio systems.

More and more audio equipment manufacturers are building their equipment with double insulated AC power wiring thus eliminating the need for an equipment ground. They are finding the use of an equipment ground causes more problems than the added cost of the double insulated power wiring.

Stray voltage
.

The earth shall not be considered as an effective ground-fault current path.
From 2005 NEC 250.4 (A) 5

True, but the presence of such a path will do no harm as long as the proper path is also present, at the service entrance (that proper path presenting a much lower impedance to fault current than the extraneous path, as diagrammed in Whitlock's paper).

The earth does not have some magical mystical power that sucks AC noise from our audio systems.

Agreed. As I admitted, you are likely correct that a ground rod near the system would accomplish nothing.

More and more audio equipment manufacturers are building their equipment with double insulated AC power wiring thus eliminating the need for an equipment ground. They are finding the use of an equipment ground causes more problems than the added cost of the double insulated power wiring.

That's interesting; maybe one of the problems they are finding is exactly what I was describing -- voltage offsets in safety grounds causing noise currents to flow through signal return paths, a problem which would be eliminated if signal ground and ac safety ground were not both tied to chassis.

Stray voltage

Interesting paper, but it doesn't seem to be particularly relevant, and I don't think it makes its case completely. His theme seems to be that cost reduction measures taken by utility companies cause ac return paths to power company equipment to be partially through the earth, instead of entirely through their wires, and that that is somehow harmful to people and animals. But I didn't see any explanation of how that current flow might result in significant voltage difference across any individual animal or person, other than brief mention of in-ground swimming pools (and I'd want to see more evidence or quantitative explanation before concluding that he is right in that case).

In any event, I don't think his paper has relevance to connecting an audio system ac safety ground to earth, when a very nearby connection to earth of that same ac ground would exist at the service panel.

Thanks for the interesting read, though!

Best for the holidays and new year,
-- Al

Timtim,

I am thinking of using an input line reactor to a seperate sub panal I have planned for my audio room.
I use them alot in my trade to stop unwanted electrical issues too and from VFD's. I do not think anyone in audio has tried this but I think it will help with power and noise issues.
I will tell you how it go's later.
Has anyone tried this?

Stray voltage

Interesting paper, but it doesn't seem to be particularly relevant, and I don't think it makes its case completely. His theme seems to be that cost reduction measures taken by utility companies cause ac return paths to power company equipment to be partially through the earth, instead of entirely through their wires, and that that is somehow harmful to people and animals. But I didn't see any explanation of how that current flow might result in significant voltage difference across any individual animal or person, other than brief mention of in-ground swimming pools (and I'd want to see more evidence or quantitative explanation before concluding that he is right in that case).

In any event, I don't think his paper has relevance to connecting an audio system ac safety ground to earth, when a very nearby connection to earth of that same ac ground would exist at the service panel.
12-24-08: Almarg

Al,
I provided the link to show what can happen if the equipment ground for a branch circuit was connected to an earth ground electrode only. In this case any ground-fault current would have to travel through the earth to return to the source. The path/s taken would depend on the least resistive path/s available.

Depending where the isolated ground rod is driven into the earth with respect to the proximity of other earth electrodes that are connected to the grounded conductor of the source, the utility transformer.
Possible ground-fault path/s back to the source?

* Through the earth to the grounding electrode system of the electrical service panel of the house that the branch circuit was fed from.

* Through the earth to the grounding electrode system of the neighbors house next door to their electrical panel then on out through the service entrance conductors to the utility transformer.

* Through the earth to the grounding electrode of the utility transformer where the primary winding and secondary winding grounded conductors are bonded together and connected to earth.

As you can see there are multiple paths the ground-fault current could take to complete the circuit back to the source. A poor conductive path I might add.