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

I'm running two new 30ft dedicated lines of 12 ga Romex, and one 15ft line. The two longer lines will be one for digital sources and one for analogue sources, with the shorter line going to my subwoofer. I'm NOT going to standard AC wall recepticles, but am going to just bring the Romex straight in to the two PS Audio power conditioners using standard IEC connectors. I'm also taking the Romex straight to the sub itself ... bypassing the need for wall recepticles and AC power cables. The system is NOT moving from where it is at, so I see no need to add extra breaks in the lines at the walls.
Here then is my question : Should I use 3 copper ground rods driven in to the ground ? One for EACH Romex line ? This would keep the grounds separated and as short as possible.
Or should I use the Romex's own grounds back to the electrical panel, and ground at ONE place below the AC panel ? This would be MUCH longer ground runs, and seems that it would make for an inferior grounding scheme ?
Obviously, I need good advice.
Thanks
timtim

Showing 3 responses by jea48

jea48
4,689 posts
 
Dedicated ground rods? Great for hunting fish worms......

Power cords can help control EMI/RFI noise....

.
jea48
4,689 posts
 
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
.
jea48
4,689 posts
 
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.
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