advice on dedicated line


Hello.

I need to have an electrician do some work on my house, and am mulling over a dedicated line for my sound system while she or he is there.

I am new to this, though, and not especially sophisticated about electrical matters. So I am wondering what exactly I want to ask for, and thought maybe you all would know.

I have an amplifier, a cd player, a Sonos unit, and a DAC.

Do I want two dedicated lines--one for the amplifier and one for everything else? So 2 20 amp circuits with 10 gauge wire?

Do I need to say something else about ground wires etc? About the breaker box?

Can I get 3 outlets on one dedicated line?

What kind of outlets do I want?

Anything else I should know?

Thanks!

mc
mcanaday
Although the electrician will say you don't need it, I went with 10 gauge wire.
Digital equipment should be on it's own dedicated circuit.
The amp should be on it's own separate dedicated circuit.
I'd go with a third dedicated circuit for the front end (preamp and what ever other gear you have or will obtain some day as long as it's not digital gear.
The three individual 20 amp circuit breakers should be placed in the service box on the side with the least nosiest appliances.
Personally, I like the Porter-Port that Albert Porter sells here on Audiogon. There are other outlet options available for more money and/or less money.
I'm sure other members will have some additional good ideas.
One big thing is all of the circuits need to be on the SAME LEG.
Which means they all come from the same 'half' of the 230volt pair of 120 volts parts.
So you don not want one line to be say from leg A and one from leg B, where A and B add up to 239 volts.
All the outlets need to be from one leg. So they never can 'add together' to make 230, but only 120 volts.
And then the outlets need great grounding. You WILL have hum issues if the electrician messes up the grounding.
So remind him at teh start tath grounding has to be done right (gauranteed no hum)
Plenty of folks cry about serious hum problems AFTER THE FACT.. due to the electrician not understanding the basic importance of proper grounding as all three will be interconnected by equipment.
"Do I want two dedicated lines--one for the amplifier and one for everything else? So 2 20 amp circuits with 10 gauge wire?"

If you have a small system and as long as your amp is not a monster, you can get by with 2 dedicated 20 amp lines. The current draw from a CDP, DAC, Sonos, or preamp is very low. Good outlets are important and so is surge protection. Later on, you'll probably want to get a power conditioner.
Thanks, all. This is very helpful. My amp is 50wpc, so I am thinking 2 lines. Lowrider57 (or anyone else who cares to answer): would I get a separate surge protector for each outlet, and can you recommend a good, moderately priced one? Also any more suggestions for good outlets? Elizabeth, I have another question on ground wires, but that will have to wait a bit because I am heading out now to go audition some speakers. :). Thanks again, everyone, for your excellent guidance. M.
Lak has it covered nicely.
The only add I would offer is that if your system is quite a distance from your service box, you may consider having them run a 50 or 60 amp sub-panel, positioned somewhere nearer to your system and then all your individual circuits would run out of the sub-panel.
Good comments by the others. I agree that two lines should be adequate for your relatively low powered system. I would add that experimentation with what components are plugged into which line could very well be worthwhile. And it is even conceivable that you could find that best results are obtained with the entire system connected to just one of the dedicated lines.

I say that because while on the one hand connecting power amplifiers and digital components to a separate line from the one powering components that generate or process low level analog signals can minimize coupling of electrical noise from the former to the latter, a tradeoff may come into play, depending on various factors such as the internal grounding configuration of the specific components. The tradeoff being the possibility of increased susceptibility to ground loop issues, especially if the connections between components that are on different dedicated lines are single-ended (utilizing RCA connectors) as opposed to balanced (utilizing XLR connectors).

If those interconnections involve analog signals, the symptoms of ground loop issues would be either low frequency hum or high frequency buzz, or both. If those interconnections involve digital signals, the symptoms would be more difficult to predict or identify, but may involve a general reduction in clarity, to an unpredictable degree.

As far as surge suppressors are concerned, for optimal protection you should have one for each dedicated line. Again there is a possible tradeoff, however, as some people find that sonics benefit from having their power amplifier plugged directly into the wall, with no surge protection or power conditioning.

I and a number of other members use this $259 8-outlet BrickWall surge suppressor/line filter with excellent results. Note that it provides some degree of noise filtering between each of its four duplex outlets, as well as between those outlets and the incoming AC.

Best regards,
-- Al
Wonderful advice all, thank you. One follow up question on the issue of the ground wire. I read this on the Martin Logan site.

"The key to reducing hum and noise is to have the electrician wire only a single ground from the audio / home theater system to the electrical service panel (see figure 2). If you are installing a dedicated or multiple dedicated lines in the Home Theater it is critical that all outlets that will be attached to the A/V system be wired with the same single ground wire, and run directly to the service panel. 'Hot and neutral' wires are attached directly to the service panels dedicated power line. Do not attach anything other than the Audio and Video system to this special dedicated line. Be sure to plan for enough outlets for the electronics, speakers, sub-woofers, video and video accessories as well as the location of each outlet (subwoofers in the rear, etc). Lighting, fans and anything not directly related to the A/V system, should be attached to a separate circuit with it's own ground, connected to the service panel."

Does this mean that even if I have 2 20 amp lines, I just want one ground for them both? Or does each line have its own ground wire?

This is really a foreign language to me, so thanks again for translating!

Margot
Margot, I believe that as you appear to suspect the statement does seem to imply that if two dedicated lines are being used, the safety ground connections of their respective outlets (the U-shaped openings of the outlets) should be connected together, and in turn wired through a single ground wire back to the circuit breaker panel. However, I feel pretty certain that if that is what the statement intends to indicate, it is wrong.

While I am an electrical engineer and not an electrician, I suspect doing that would be neither code compliant nor proper practice. I suspect that your electrician will tell you that each dedicated line has to have its own safety ground connection running back to the panel together with its AC "hot" and neutral wires. (The "hot" connection, btw, being the smaller of the two vertical slots on the outlet, and the neutral connection being the longer of the two vertical slots, which is T-shaped on a 20 amp outlet).

Hopefully one of our electrician members will comment further.

Best regards,
-- Al
Thanks, Al! This makes more sense to me, and I am glad to have the advice of an electrical engineer. cheers, Margot
A 15 amp circuit is 1800 watts,a 20 amp circuit is 2400 watts. I don't know of any audio or video system that comes close to using that much power! I think this is all overkill if I am wrong please someone clue me in? I always thought it was safer to have a 15 amp circuit breaker so it would trip before frying your components! Like I said if I am wrong please explain! Thanks much
I was going to make a similar comment to Yogiboy.
No need for TWO 20 amp lines for 99.9% of all systems.
Now if you have two 1,000 watt monoblocks well yeah maybe two would be better.
One really SOLVES all the ground issue two lines create.
Elizabeth, now that makes sense! Thanks
I doubt that there is much likelihood that having a 15 amp breaker instead of a 20 amp breaker would ever make a meaningful difference with respect to protection of the equipment, especially given the protracted breaking times circuit breakers generally have for marginal overloads. The fuses in the components are primarily what protect the components. The breakers are there primarily to protect against overheating of the house wiring, and to protect against the possibilities of electrocution or fire that might otherwise result if an insulation failure in a component were to cause a short between AC and chassis.

Yes, two 20 amp lines, or even one 20 amp line, is certainly overkill with respect to the current requirements of Margot's system, and the majority of other systems. However, the associated heavier gauge wiring, and perhaps also the more substantial outlet and breaker, could conceivably provide a sonic benefit by reducing both AC voltage loss and AC voltage fluctuation that would occur in the wiring as a result of the fluctuating current draw of the system, particularly of the power amplifier.

So while I see the possibility of a benefit from having a 20 amp line rather than a 15 amp line, albeit perhaps a slim one, I see no downside.

Regarding two lines vs. one line, as I indicated above there are tradeoffs involved, which don't have much if any predictability. And experimenting with different configurations of what is plugged in where is arguably the only way to assure optimal results. So if Margot is going to the trouble of having one dedicated line installed, I see no reason for her to not have a second one installed at the same time, thereby providing the flexibility to try different configurations.

Best regards,
-- Al

Speaking from experience, yes, the size of wire on the dedicated lines will make a difference. About 3 tears ago, a friend decided to experiment with this, mainly because another close friend of his was an electrician. He had always used 2 dedicated lines of 12 gauge with basic heavy duty outlets, then just changed the wire to a standard 10 gauge romex. From there, he changed to the VH Audio 10 gauge romex. In each case there was a definite improvement in overall sound quality emerging from an even blacker background. Then he experimented with outlets, finally deciding on the Porter Port, and I agree, the Porter Port sounded the best overall. I do feel very fortunate to have this first hand experience on dedicated lines, and can say that the possibility stated by Al is a reality.
Al, in your post above, you write the following about surge protectors:

"I and a number of other members use this $259 8-outlet BrickWall surge suppressor/line filter with excellent results. Note that it provides some degree of noise filtering between each of its four duplex outlets, as well as between those outlets and the incoming AC."

You and I may have traded messages before about the benefits and downsides associated with surge protectors. Even still, let me pick it up one more time.

I use a surge protector for my electrical components, except for my subwoofer and power amp. In the later case, I seem to recall that ARC advised me to just plug it into the wall, for the reasons (benefits) you mentioned above. Namely, better access to AC current when the amp is drawing power, especially when handling dynamic transients. Of course, the downside is that my amp is more exposed to damage in case of an AC power surge (e.g., lightening strike).

Two questions. First, in your opinion, does the Brickwall surge protector constrict the amp's access to AC wall current to any significant extent, at least to the point where I might be able to detect a change in sonics?

Keep in mind that my amp is a 150 wpc tube amp. ARC specs it as drawing about 400 watts at idle and about 800 watts when pushing. In addition, the amp has a pretty robust power supply (1040 joules). I assume that the stored power supply would be tapped first during dynamic transients. Perhaps, the amp's power supply acts like a "shock absorber" in that the amp may not need to draw large amounts of AC power in a short time frame if it can draw off the internal power supply first. That's just an intuitive guess.

Second, in your opinion, how much risk is there that an AC power surge will and could take out my amp. I live in the Philly area and am tied into a large urban utility grid. And yes, we are affected by occassional power outages, espcially weather related (e.g., most recently resulting from the snow and ice storms affecting the NE).

On balance, do you think the risk of unprotected AC access outweighs the benefits of direct AC access, sans artifacts?

Thanks,

BIF
TLS, thanks for the inputs.
02-08-14: Bifwynne
In your opinion, does the Brickwall surge protector constrict the amp's access to AC wall current to any significant extent, at least to the point where I might be able to detect a change in sonics?
Bruce, I've never performed any carefully controlled experiments to assess that in my system. And in any event I would not want to extrapolate results in my system to other systems, especially those that include Class D amplification (for which AC current draw fluctuates dramatically with the dynamics of the music), such as you have in your subwoofer.

As I'm sure you realize, there are undoubtedly some audiophiles out there who would contend that it degrades the sound big-time, and others who would contend that it is completely transparent. And undoubtedly there are some who would reject it "a priori" because it does not have a detachable power cord that can be upgraded. I chose it after weighing the opinions and experiences of many others, as well as its design characteristics, which to me are suggestive of a "less is more" approach to line filtering, while of course taking its price into account.
In your opinion, how much risk is there that an AC power surge will and could take out my amp. I live in the Philly area and am tied into a large urban utility grid. And yes, we are affected by occasional power outages, especially weather related (e.g., most recently resulting from the snow and ice storms affecting the NE).
Your guess is as good as mine. I suppose a good answer would be that the risk is minimal but not negligible.
On balance, do you think the risk of unprotected AC access outweighs the benefits of direct AC access, sans artifacts?
Personally I would not want to have any expensive audio equipment unprotected, but obviously that's a personal decision that each audiophile has to make for him or her self.

Best,
-- Al
I live in philly in a neighborhood that runs off the same transformer and we're prone to lightening strikes. Even with my modest system I use a Furman Pro pwr strip for my Sunfire amp, but as Al stated, effect on SQ is system dependent. There have been more than a few nites where I've lost power and heard the breakers on the surge protectors click off. You have an awesome amp, Bifwynne and its worth trying one.
FWIW I like the design of the Brickwall with it's isolated receptacles
Uuuuhhm, maybe the most effectice "surge protector" for my amp is to simply pull the plug when not in use, and not to use my stereo during storms. The other gear is surge protected, if such devices even work.
Here's a question to all you knowledgeable folks...Its been mentioned many times to have the digital components on their own dedicated line; now I'm assuming this means a transport cabled to an external DAC or a hard drive setup.

Why is it recommended not to share the same AC line as analogue components?
Secondly, is a surge protector using isolated receptacles an alternative?
Thanks.
Its been mentioned many times to have the digital components on their own dedicated line.... Why is it recommended not to share the same AC line as analogue components?
The most significant generators of electrical noise in most systems are components containing substantial amounts of digital circuitry, and power amplifiers. Some of that noise will be fed back into the power cord of the component which generates it, from where it will to some degree propagate through the power wiring to analog components, with unpredictable but potentially perceptible adverse sonic effects.

Everything else being equal, the longer the wiring path is between the power cords of noise generating components and components that may be susceptible to that noise, the more that noise will be attenuated. The most significant reason for that perhaps being the inductance of the wiring. The inductance of wiring is proportional to length. A given amount of inductance presents an impedance which is proportional to frequency. Electrical noise generated by digital circuitry tends to be at very high frequencies, and therefore can be significantly attenuated by the inductance of a substantial length of wire.
Secondly, is a surge protector using isolated receptacles an alternative?
It's certainly an alternative to consider and/or try, and in fact that's what I do with my CDP, which is the one digital component in my system. How that approach would compare with having a digital component on a separate dedicated line can't be predicted with any certainty, as it would depend on many unpredictable and unknown variables, including the technical characteristics of the noise generated by the particular digital component, how the particular analog components would react to that noise, the characteristics of the filtering that is provided between receptacles, and the susceptibility of the particular components to ground loop issues if they were to be put on separate dedicated lines.

Best regards,
-- Al
Elizabeth is correct,,,there is really no need for more than one 20 amp line and you are looking for grounding issues otherwiseÂ…even some manufacturers discourage it
Thank you, Al. A great explanation that I can understand.
What an education! Thanks, everyone. Even with pros and cons, I confess I am tempted by the simpler route of one 10 gauge 20 amp line with the Porter -port. Would it be workable for me to get 6 outlets instead if 4 in case I ever wanted to plug in a small fm receiver to listen to the news? Or is that pushing my luck?

Also I am assuming that if I just one 20 amp line the points Elizabeth initially raised (circuits on same leg, nothing adding to more than 120) are not things I need to worry about.

In fact, with the single 20 amp line is there anything special I need to tell the electrician other than I want 10 gauge wire, to put the line on the least noisy side of the box, that I want nothing but my audio on this line, and to be careful with the ground wire? Is there anything else I would need to specify?

Thanks again very much. I would be lost without you folks!

Margot
For what it's worth I have two 20 amp dedicated lines for my 2 channel system. I ran #10-2 with ground NM-B cable. (Romex is a trade name of NM-B cable). Each run is about 75' each. Digital equipment on one line, analog on the other. My system is dead quiet.

Al, Your last post was right on IMO.
.

Here is a post by the late Robert Crump.

Quote.
"Posted by rcrump (M) on February 5, 2004 at 07:15:55
In Reply to: Re: Why solid over stranded??? posted by Jwm on February 3, 2004 at 06:20:47:"

"Solid core Romex has an absolute ton of inductance and you can use that to roll off the digital backwash and end up isolating your analog from digital with yards of the solid core Romex in the walls. Romex is insulated with PVC and, again I will say that PVC is what you want rather than anything faster as you just want to pass 60hz and attenuate anything above that.....Stranded wire, especially a twisted lay, will pass high frequencies better, exactly what you don't want to do with 60hz AC.......
http://www.audioasylum.com/audio/cables/messages/8/88644.html

Most of the AC noise/hash on the mains of our audio equipment is connected to is caused by the power supplies of the audio equipment.
Dedicated branch circuits will decouple audio equipment power supplies from one another.

http://www.middleatlantic.com/pdf/PowerPaper.pdf

Jim
Excellent post Jim. Thanks. That's exactly where I'm heading. I may go for 2 or 3 dedicated Romex circuits. A 15 amp job for my CDP. A 15 or 20 amp line for just the amp, although I suspect 15 amps would be major overkill since the amp pulls about 800 watts (or 7.5+ amps when driving a heavy load). And a 3rd line for the rest of the my gear.
Would it be workable for me to get 6 outlets instead if 4 in case I ever wanted to plug in a small fm receiver to listen to the news? Or is that pushing my luck?

IMO, a better idea is to use a high quality power strip for your low current components and plug your amp into the wall. Then you won't run out of receptacles and you'll be protected.

a very popular power strip by Furman...
http://www.amazon.com/Furman-Standard-Conditioning-Aluminum-Protection/dp/B0009GI65Q
Excellent post Jim. Thanks. That's exactly where I'm heading. I may go for 2 or 3 dedicated Romex circuits. A 15 amp job for my CDP. A 15 or 20 amp line for just the amp, although I suspect 15 amps would be major overkill since the amp pulls about 800 watts (or 7.5+ amps when driving a heavy load). And a 3rd line for the rest of the my gear.
02-09-14: Bifwynne

Bifwynne,

Install only 20 amp dedicated branch circuits. Wire size #12 solid core copper bare minimum. Per NEC Code a 20 amp NEMA 5-20R receptacle can only be installed on a 20 amp circuit. A NEMA 5-15R 15 amp duplex receptacle can also be installed on a 20 amp branch circuit.
Porter Ports are NEMA 5-20R 20 amp duplex receptacles.

How long are the runs from the electrical panel to your equipment? Don't forget to figure up and down, over and around, when figuring the lengths.

Tell the electrician to try and keep each branch circuit length the same. Do not mix wire sizes. Make all dedicated branch circuits either #12 or #10 wire.
Jim

Thanks again, all. I've reread this, and if I get Al's point, I might be better off with 2 20 amp circuits; but if I end up with grounding issues then I can put everything on one circuit and then I'll be at the baseline of where I would have been if I just started with one. So two is a way to optimize my results...but of course I have to get an electrician who will do this all carefully. And I guess if I hit resistance with the electrician, I can always drop back to one line and this will still be better than what I have currently.

A lot of moving parts!

A few other questions:
-I'm gathering from Al's post above that I should I get around to upgrading power cords, longer is better? Is this also true of interconnects?

-Is it enough to tell the electrician I want 10 gauge wire? Or do I need to supply him or her with it? If so, where would I get #10-2 NMB? (I assume this is what I want.)

I confess that I had a dream last night that I burned down my house!

Thanks again, everyone.

Margot

One other question occurs to me, just so I understand:

If I had a turntable that would most likely go on the dedicated line with the amplifier, unless the amplifier was Class D? In that case, the CDp, DAC, and Class D amp would be on one line, and the turntable would be on the other? (And then of course there is Al's point about experimentation to see if they all sound better on one line anyway, etc.) Is this generally the right idea? Thanks...
Jim, thanks for chiming in. Margot, Jim (Jea48) is the foremost expert on electrician-type matters on these forums.

To answer some of your recent questions:
Would it be workable for me to get 6 outlets instead if 4 in case I ever wanted to plug in a small fm receiver to listen to the news? Or is that pushing my luck?
That may be within reason, but as Lowrider indicated it would probably be simpler and better to expand the number of outlets with a power strip. The one he referenced includes a surge suppression function, as does the more expensive BrickWall device I suggested earlier. If you wanted to further expand the number of outlets provided by a surge suppressor/power strip, you could plug into one of its outlets a simple but well made power strip having no surge suppression or line filtering. I need a lot of outlets for my system, more than the 8 that are provided on the BrickWall, and I use this Hammond power strip for exactly that purpose, plugging it into one of the outlets on my BrickWall. For good measure, I connect relatively non-critical components (e.g., FM tuner, cassette deck) to the power strip, and more critical ones directly into the BrickWall, although I'm not sure that has much if any significance.

The one thing I would not do is to have two power strips that both provide surge suppression and/or line filtering in series with each other. Don't ask me why; just instinct :-)
I am assuming that if I just have one 20 amp line the points Elizabeth initially raised (circuits on same leg, nothing adding to more than 120) are not things I need to worry about.
Correct.
I'm gathering from Al's post above that should I get around to upgrading power cords, longer is better? Is this also true of interconnects?
Generally speaking the standard power cord length of 6 feet or thereabouts is considered to be optimal. In the two-line situation, the benefit I referred to of higher inductance between the power inputs of noise-generating and noise-susceptible components results almost entirely from the length of the house wiring, from the outlet of one dedicated line back to the circuit breaker panel, and from there to the outlet of the other dedicated line. The inductance of the power cords is relatively insignificant.

In the one-line situation, it's possible that having a longer cord on some of the components might be beneficial in some cases, but other effects such as voltage loss might outweigh that.

Interconnects (and speaker cables) are a completely different story. The shorter those cables are the better, if the goal is accurate signal transmission. The one situation in which a longer interconnect cable might be beneficial is if you were trying to compensate for some coloration in the system, such as an overemphasized treble. But a better way of fixing that kind of problem would be to determine and address its root cause.
Is it enough to tell the electrician I want 10 gauge wire? Or do I need to supply him or her with it? If so, where would I get #10-2 NMB? (I assume this is what I want.)
The electrician will supply it.
If I had a turntable that would most likely go on the dedicated line with the amplifier, unless the amplifier was Class D? In that case, the CDp, DAC, and Class D amp would be on one line, and the turntable would be on the other?
The turntable should generally (and perhaps always) be on the same line as the component it is connected to. If I recall correctly you have a Creek 50A integrated amplifier, I presume with its optional built-in phono stage. If so, the turntable and the 50A should most likely be on the same line, with the digital components probably being best located on the other line (subject to experimentation).

I'm pretty certain, btw, that the power amplifier section of the 50A is Class AB, for which fluctuations in AC current draw as a function of the dynamics of the music are mid-way between Class D (very high fluctuation) and Class A (very little fluctuation). See this Wikipedia writeup to get a general idea of what these class designations refer to.

In summary, as you've no doubt gathered by now the life of a dedicated audiophile is not a simple one :-)

Best regards,
-- Al
There are many here that are Electrical Engineers and/or Electricians. Remember that any competent Electrician will do the work to "code". People have posted their experiences and "what they would do". For the system that you listed, two "dedicated" lines would suffice. Dedicated means, separate hot, return and ground for each "dedicated" line. make sure you tell the electrician that specifically. Some Electricians will share neutrals and grounds on individual lines. You don't want that. Although it may be to code, it is much better to rune separate hot, return and ground wires per dedicated line. In my opinion, two completely dedicated three wire runs are sufficient for you. Depending on the cost, you might want three for future system expansion sake. In my system, this is what I did. I have raised foundation with crawl space so it is much easier to install new lines (relatively speaking, it is still about 2.5' crawl space, not fun), than if one has concrete foundations. So, I ran three dedicated (three wire) lines from the service panel to the specific locations required (this is important) in my listening room. My low level electronics are all (and I do mean all) connected to a Transparent Audio power conditioner. This includes CD Transport, DAC, Music Server, TT, Pre-amp, Phono Stage, tuner. I have two stereo amplifiers that I use to bi-amp my speakers. Each Amp using its own dedicated line. Here is what I experienced. No hint of a ground loop, no hum whatsoever. My noise floor droped to an amazingly low level. Also, I don't buy the argument that everything must be connected to the same tap on the service panel connection. That is really not true and it is really a violation of code. Any competent electrician will make sure that your service is balanced on both sides. You get ground loops, hum and electrical problems when they "aren't" balanced. I have experienced no problems, quite the opposite. It is dead quiet, no ground loops, no hum, no noise and wonderful sounding. So, definitely two and maybe three (if the cost is low) three wire dedicated lines and you are good to go.

enjoy
Minorl, thanks for your comments, most of which I agree with. However, I would respectfully disagree with the following, especially in a situation such as Margot's where the power consumption of the system is not particularly high:
I don't buy the argument that everything must be connected to the same tap on the service panel connection. That is really not true and it is really a violation of code.
Regarding the sonic issues that are involved, see my post here, and the links provided therein (the main one being the ExactPower link, which Jim had called to our attention earlier in that thread). (Ignore the first paragraph of my post, which is on a different subject).

Regarding code compliance, Jim can speak to that more knowledgeably than I can, but it seems to me that the only way a system having typically modest power requirements such as this one could cause non-compliant allocation of loading between the two phases would be if the existing installation were already marginally non-compliant, and the electrician then chose the wrong phase (i.e., the one that is more heavily loaded) for the dedicated lines.

The bottom line: I agree with Elizabeth's initial statement regarding this issue.

Best regards,
-- Al
Al; Thanks for the response. I can tell you that I have reviewed many home systems personnaly and each with dedicated lines that were run balanced to the panel as I indicated, and they did not negatively impact the system or sound. However, If people want to wire to one side of the panel. More power to them. The most important thing is to have dedicated (three wire) lines. I advocate plugging all low level devices into the same line/conditioner to help to eliminate ground loops. For amps, several things can be of consideration. If the amps are low power amps, then yes, they can be both share the same dedicated line. however, for high power amps, I recommend separate dedicated lines per amp. the problem will arise when talking to a qualified electrician and he/she ask what the power ratings are of the equipment. They will want to balance the loads as per code. Some may do it per the customer's request. Not a major issue for me. The real issue is dedicated (three wire) lines.

enjoy
MANY THANKS to all of you for your careful and detailed advice. I think I am ready to call an electrician!

cheers,

Margot
Al,

Here is a white paper of a 2012 seminar by Bill Whitlock.

http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

Check out grounding, starting on page 31.

Note page 35, for those that have to use metallic conduit for the branch circuit wiring. MC cable with an aluminum armor is the best. Conduit runs with loosely randomly installed wires pulled in the conduit is the worst for ground loops.

I would have liked to have seen Bill comment on the effects of multiple dedicated branch circuits sharing the same conduit raceway addressed.

Also check out pages 200 through 212.
.
Jim
Very informative thread and a model for how this forum should operate. I am no expert on this but I have to agree that one dedicated line should be plenty for your (and most other) systems. As has been stated, running a single line avoids a host of potential problems associated with multiple lines. I am running a single line to a bank of 4 Porter Port duplex outlets behind my rack. I also turn off my digital playback machine when I'm listening to vinyl--not sure if it makes a difference but there you go. Finally, while there have been a number of suggestions about powerstrips etc. I don't think I see reference to the Environmental Potentials 2050 which acts as both a surge suppressor and noise reducer. It is made for very high technology industrial applications but has found favor among audiophiles as well. I had one installed on my panel along with the dedicated line and my system is dead quiet. Hope this helps.
Great reference, Jim (Jea48), as I'd expect from Mr. Whitlock. And all of the sections you referenced make perfect sense to me. Thanks!

Amazing that it took until the last few years for an explanation and measured verification to finally be presented for "what drives 99% of all ground loops."

I note that rate of change of current is indicated on page 31 as being a significant variable, which reinforces the significance of what I said earlier about not extrapolating results obtained with one amplifier class (i.e. A or AB or D) to other classes.

With respect to the comparison chart on page 35, I wonder what the results would be for the situation that probably exists in many older homes where the metal conduit IS the safety ground connection, for example where older two-prong outlets have been replaced over the years with three-prong outlets, or where a three to two prong adapter is being used, with its ground connected to the cover plate screw. I would guess the results of his test in those situations would be fairly good. I assume, though, that modern code doesn't permit installation of conduit containing only two conductors. Am I correct about that?

I note that the BrickWall I had suggested to Margot is based on the series mode non-MOV technology that is recommended in the paper. And I seem to recall that there may have been some kind of relation between BrickWall and the SurgeX brand he specifically mentions.

Regarding the EP-2050 Dodgealum suggested, having looked at the datasheet and other info on it provided at their website it certainly seems to be a good product, that would be a worthwhile investment in many cases. But as a whole-house protector and noise reducer it appears that it won't do anything to reduce the effects of noise generated within the system, certainly in an application that utilizes a single dedicated line. Also, I note that it lists at $730, plus the cost of professional installation. Also, I would note that the absence of audible noise does not necessarily signify that noise is not a problem. Digital noise has very substantial frequency content far above the audible frequency range, and that high frequency content can have effects within the audible spectrum when introduced into analog circuitry as a result of intermodulation with signal and other effects.

The bottom line would seem to be that given the success many audiophiles achieve with both multiple dedicated line and single dedicated line approaches, and given the system dependency and technical unpredictability of the tradeoff between the possibilities of ground loop issues and inter-component noise coupling, it seems clear to me that there is no one size fits all answer, and in general there is no approach that can be determined to be optimal apart from experimentally.

Best regards,
-- Al
I assume, though, that modern code doesn't permit installation of conduit containing only two conductors. Am I correct about that?
02-11-14: Almarg
Al,

As for NEC 2011 Code, Rigid, IMC (intermediate Metal Conduit), EMT (thin wall), are reconized as an equipment grounding conductor.
Flexible metal conduit 6' or less in length is also acceptable for use as an equipment grounding conductor provided the connectors are Listed for use as equipment grounding means, and the branch circuits is 20 amps or less.

Remember NEC Code is bare minimum. The AHJ (Authority Having Jurisdiction) in the area a person resides may not allow the above metal conduits to be the sole equipment grounding conductor. The AHJ may require an equipment grounding wire to be installed in the conduit with the other branch circuit wires.

The problem I have with using any metal conduit for the equipment ground is the continuity integrity of the couplings and connectors to maintain a good conductive electrical connection over the passage of time. Not to mention how well the conduit installation, fittings tightness, was to begin with.

As for the white paper....
I was glad to see actual testing done for an equipment grounding conductor sharing the same raceway or cable as the current carrying conductors of a branch circuit.

I always thought a voltage could be induced from the current carrying hot and neutral conductor over onto the equipment grounding conductor on a long branch circuit run. We now know why many audio enthusiasts recommended using NM-B cable, (Romex is a Trade name of NM-B), for audio equipment branch circuits.

One thing for sure, conduit runs where the wire is installed after installation is the worst thing for audio. And to repeat what I have said in the past, dedicated branch circuits should not share the same raceway, conduit, with other branch circuits.

For those out there that have to use conduit I suggest MC cable with aluminum armor and solid core conductors. MC can be bought with solid or stranded wire conductors.
MC Cable
http://www.afcweb.com/product-category/mc-metal-clad-cables/
.
.
**Just an added note.
Old homes built before around the middle 1950s and earlier may be wired with old BX cable wiring. Construction of the cable is 2 insulated cloth covered conductors with a steel spiral armor cover around the conductors.
The receptacles back then were the old 2 wire type.

The armor on this BX cable should not be used as an equipment grounding conductor. Not only is the steel armor not an effective ground fault path for fault current, neither is the electrical connection of the BX to box connectors.

NEC 1959 Code required AC/BX cable to have a continuous bonding strip installed under the armor so the cable could be used as an equipment grounding conductor. Just guessing the BX to box connectors were still the same old connectors. By NEC 1962 Grounding type receptacles were required.

Here are a couple of Links.

http://www.inspectorsjournal.com/forum/topic.asp?TOPIC_ID=10144

http://www.dslreports.com/forum/r26797846-using-BX-cable-as-a-ground-

Jim
Jim, thanks for the detailed and nuanced answer. Good stuff!

Best regards,
-- Al