Does anyone have opinions as to the best type of electrical wire to use for a dedicated audio circuit? My current dedicated circuit is 20A romex, but I'm considering replacing it with 20A or 30A twisted wire in metal conduit.
Dedicated Audio Power Circuit
- Thread starter LenWhite
- Start date
There may be some theoretical benefit to twisted pair but in practice when inside a grounded metal conduit it won't matter. A bigger change, if any, would be to simply go from 12 AWG (typically used here for 20A) to 10 AWG to reduce IR drop, but I suspect you would not notice the difference in practice.
I wonder how long before somebody uses shielded silver inside conduit from their service to the outlets...
I wonder how long before somebody uses shielded silver inside conduit from their service to the outlets...
Bruce B
WBF Founding Member, Pro Audio Production Member
I'm using all JPS labs 10/3 in-wall cable in my studio... about 1000' of it!! 
It IS UL approved....
It IS UL approved....
It's only a matter of time until someone pays their power company to run dedicated lines from the substation directly to their house.
Until someone has a scientifically proved analysis of the effect of power wiring in power cables, we will go on acting empirically or believing people we want to trust. In these matters, I enthusiastically endorsed the Nordost claims that the more important are just the last 2 meters before entering the equipment. Accordingly, my three separate mains lines used AWG 11 good quality copper wire - equivalent to using AWG 8 in 110V systems. The great electricity craziness only starts after entering the room!
1000 feet = $250,000 Natural Gas Service. I was looking at a house closer to my wife's area of work. Unfortunately the house used electricity for heating, therefore I looked into having the local gas provider extend their service area. The figure shown previously is not exact, but close enough to what it would take [what it would cost me] for the gas to be run 1000 feet from the closest gas main & then to the house.
Guess who did NOT buy the house.
It might be cheaper [and the person would have EXTREMELY CLEAN & STABLE ELECTRICITY] to use an industrial natural gas turbine generator rather than running a dedicated electric line from the substation. As a byproduct you would have great cogeneration.
zz.
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Bruce B
WBF Founding Member, Pro Audio Production Member
I have one from the street to my Equi=tech, though there was no option for the Audiophile meter...
I have a dedicated 80 amp sub-panel in the basement with five separate 20 amp lines to my system. One line to each of four power amps and one for all the sources, preamps and active crossovers. If I need more power than that, I'm just SOL. . . .for now.
As to the power wire/cable, this newer Bill Whitlock & Jamie Fox paper adds a new prospective.
"Ground Loops: The Rest of the Story"
Bill Whitlock, AES Fellow and Jamie Fox, P.E.
This paper was presented at the AES 129th Convention, 4-7 November 2010, San Francisco, CA, USA
ABSTRACT
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.
http://xa.yimg.com/kq/groups/20963848/268252969/name/Whitlock-Fox+-+Ground+Loops+.pdf
"Ground Loops: The Rest of the Story"
Bill Whitlock, AES Fellow and Jamie Fox, P.E.
This paper was presented at the AES 129th Convention, 4-7 November 2010, San Francisco, CA, USA
ABSTRACT
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.
http://xa.yimg.com/kq/groups/20963848/268252969/name/Whitlock-Fox+-+Ground+Loops+.pdf
Is the below correct???
Good morning Speedskater & other members who want to join in.
Question: From what is written in the ABSTRACT "It is shown that simply twisting L-N pairs in the premises wiring can
profoundly reduce system noise problems."
If this is correct and one is to build from scratch, it would be necessary to use commercial level hard metal conduit [unlike traditional residential Romax, etc. with no hard metal conduit]. This way the individual hot & neutral could be twisted before and as being pulled through the hard metal conduit.
Metal conduit acts in place of the green grounding wire that is found in Romax type wire systems. ?Would it be of benefit to include a green ground wire in the twist?
One then must heavily spec. oversize conduit for the increase size & friction of the twisted wires being pulled through.
??? Is the above correct???
zz.
'zz' you really need to read parts of the white paper. But don't try to read the patent application, as it will turn your brain to mashed potatoes.
If I understand the below section (page 6) of the "Ground Loops: The Rest of the Story" Bill Whitlock, AES Fellow and Jamie Fox, P.E.; a twisted-pair with straight ground should be by far the best approach for a dedicated audio circuit.
The “Twisted L-N” data is for a sample in which line and neutral conductors were twisted at about five twists per foot. The twisted-pair and a straight ground wire, shown in Figure 4, were then placed in a 6.1 m (20-foot) section of trade-size 1-inch (27 mm) plastic (PVC) conduit. No attempt was made to optimize positioning of these wires.
All the measured data is summarized in graphical form in Figure 7. The configuration shown above seems to offer the lowest ground voltage induction of any tested - the “Worst Case” is over 1,000 times worse!
The “Twisted L-N” data is for a sample in which line and neutral conductors were twisted at about five twists per foot. The twisted-pair and a straight ground wire, shown in Figure 4, were then placed in a 6.1 m (20-foot) section of trade-size 1-inch (27 mm) plastic (PVC) conduit. No attempt was made to optimize positioning of these wires.
All the measured data is summarized in graphical form in Figure 7. The configuration shown above seems to offer the lowest ground voltage induction of any tested - the “Worst Case” is over 1,000 times worse!
OK, I have read it [my computer had told me NOT to open it].
Thus, as LenWhite also posted: "The “Twisted L-N” data is for a sample in which line and neutral conductors were twisted at about five twists per foot. The twisted-pair and a straight ground wire, shown in Figure 4, were then placed in a 6.1 m (20-foot) section of trade-size 1-inch (27 mm) plastic (PVC) conduit." >>> is the way to do your electrical <<<.
Thank you,
zz.
Bruce B
WBF Founding Member, Pro Audio Production Member
Bruce, Are the JPS Labs cables approved to install in-wall without conduit like romex?
Bruce B
WBF Founding Member, Pro Audio Production Member
Bruce,
Very nice paper, it seems we are back to Electromagnetism classes in the old days. This was a classical problem : two parallel conductors of lenght L placed at location X,Y are carrying AC currents X1 and Y1 please calculate the EFM induced in a parallel loop placed in position Z. Nowadays most students would just introduce the values in a EM simulator ...
Do JPS Labs twist the three conductors? The approach stated in the paper tries to minimize the EMF induced in the ground line, but ignores the filter action of the capacitors formed by the ground wire and signal wires. One question immediately arises : what is more important in a power cable - minimizing ground noise due to the current flowing in the wires or RF filtering of other types of noise?
In many labs where ground noise would be critical the mains live and neutral wires are positioned far away from the ground wire - distance also helps solving this problem very efficiently.
+1. Twisting L+N works the same as twisting any signal pair to reduce common-mode noise (since both sides of the signal, in this case L and N, see the same signal so it is rejected when you look between the two sides). Twisting all three (L+N+safety ground) introduces an imbalance but also another ground return. Could hurt or help, probably hurt since (off the cuff) I think at best it would do nothing and at worst add noise to the coupled pair "inside" the twist. Been a long time since my last EM course, however.
Is PVC used as conduit of electrical runs? In the last build I saw the conduit was all metal. I suspect it depends upon the current code, which I am far to lazy to go look up.
Is PVC used as conduit of electrical runs? In the last build I saw the conduit was all metal. I suspect it depends upon the current code, which I am far to lazy to go look up.
Yes, PVC electrical conduit is allowed in residential and commercial. Of course this depends on the location. Many times service to the panel from the ground [maybe drops also] must be rigid metal [vs. feeds from the panel].
Google IBC - International Building Code & specifics for your area.
zz.
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