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

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.

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.[emphasis added]

Yes, I agree completely, that would be a definite no-no.

Thanks for the good references!

Regards,
-- Al

OK ... Timtim back with this thread. I was going on advice from a tech at PS Audio about the dedicated grounds. Personally, I don't really care which way I do it, as long as it works as well as possible.
Running different dedicated lines to keep my digital and analogue equipment separated sounds like a no brainer, but if the grounds are tied together for these lines, are they truly separated ? Then again, noise usually comes in on the neutral leg anyway.
Lastly, I can't see ANY good at all from running independant ground rods for each line, then grounding gain at the panel. That sounds like a ground loop just waiting to happen.

Timtim,

As has been said, it is essentially an absolute must to have a ground rod at the service entrance, that serves ALL runs. For reasons of code compliance, effective circuit breaker operation, lightning protection, etc.

No one in this thread has advocated independent ground rods for each line that is run to the system. And I think that Jea has effectively made the case that having even a single ground rod dedicated to the system is pointless, as well.

The question of tying the dedicated ground runs (not rods) together at the system is a little less clear cut. As I indicated earlier, there is both potential upside to keeping them separate (improved isolation) and potential downside (offset voltages between chassis causing noise currents to flow in common with signal returns).

That downside would pretty much be negated, I think, in the case of a system that had balanced interconnects. But most systems have some or all of their interfaces single-ended. For those cases, I am not in a position to offer generally applicable guidance as to whether the upside or downside is more likely to prevail. It could be that trial and error is the only way to tell in a particular case. And as I said earlier, a more ideal solution would be to make use of isolation transformers as discussed in the other thread I referenced. It seems pretty widely agreed that both the isolation they provide and the filtering that results from their limited bandwidth make them a very effective approach.

Regards,
-- Al