RE twisting:
Last week I read a paper that favored twisting the hot and neutral together and leaving the ground separate. Pull the three wires through conduit. This has been touted as the way to reduce the induction effect of the H and N on the ground, reducing induced ground voltage that causes noise.
Bill Whitlock (Jensen Transformers) and Jamie Fox presented the paper at last November's AES convention that supported this approach with test data. Titled: "Ground Loops: The Rest of the Story", the twisted configuration offered lower ground voltage induction than Romex (where the ground is between the other conductors) and aluminum MC (metal clad with the three wires configured symmetrically inside).
The synopsis from the AES library website: "The mechanisms that enable so-called ground loops to cause well-known hum, buzz, and other audio system noise problems are well known. But what causes power-line related currents to flow in signal cables in the first place? This paper explains how magnetic induction in ordinary premises AC wiring creates the small voltage differences normally found among system ground connections, even if isolated or technical grounding is used. The theoretical basis is explored, experimental data shown, and an actual case history related. Little has been written about this elephant in the room topic in engineering literature and apparently none in the context of audio or video systems. It is shown that simply twisting L-N pairs in the premises wiring can profoundly reduce system noise problems."
Hope that helps. I am taking this approach on my dedicated lines (with isolated grounds) from my sub panel.
David
Last week I read a paper that favored twisting the hot and neutral together and leaving the ground separate. Pull the three wires through conduit. This has been touted as the way to reduce the induction effect of the H and N on the ground, reducing induced ground voltage that causes noise.
Bill Whitlock (Jensen Transformers) and Jamie Fox presented the paper at last November's AES convention that supported this approach with test data. Titled: "Ground Loops: The Rest of the Story", the twisted configuration offered lower ground voltage induction than Romex (where the ground is between the other conductors) and aluminum MC (metal clad with the three wires configured symmetrically inside).
The synopsis from the AES library website: "The mechanisms that enable so-called ground loops to cause well-known hum, buzz, and other audio system noise problems are well known. But what causes power-line related currents to flow in signal cables in the first place? This paper explains how magnetic induction in ordinary premises AC wiring creates the small voltage differences normally found among system ground connections, even if isolated or technical grounding is used. The theoretical basis is explored, experimental data shown, and an actual case history related. Little has been written about this elephant in the room topic in engineering literature and apparently none in the context of audio or video systems. It is shown that simply twisting L-N pairs in the premises wiring can profoundly reduce system noise problems."
Hope that helps. I am taking this approach on my dedicated lines (with isolated grounds) from my sub panel.
David