About a year ago I installed a dedicated 20 amp line for my system...and went as far as modding the whole power structure from the street transformer to my panel to my house...at some fairly major expense. The result was certainly an improvement for my system. Recently i got to thinking that a lot of us have a system that utilizes the standard 15amp line that more than likely only supplies one other component in our rooms...and that is the lights. While lights can be noisy on the system, particularly if they are halogens, then this is a source of considerable hash and noise. However, since the only other thing shared by this line are the lights...and not the more power hungry grabbing stuff..like the refrigerator, or the Ac etc, then simply playing the system in the dark should essentially allow for a dedicated line effect to materialize on the gear that is attached to this line as well. The standard room convenience outlet( which is what we are talking about here) is 15 amp breaker protected and is only supplying the lights and the convenience outlet in a room....so ( assuming that this is the case--and the lights are the only thing supplied besides the outlet) what is the real advantage to the 'true' dedicated line ? Twenty amps is more than a lot of auto gear needs, so I doubt that is the issue...thoughts?
I use a dedicated 30 amp line to power my
system, and it works great.
In many jurisdictions, that would require the use of 30A receptacles, which would in turn mean that you'd need to modify your equipment to have 30A plugs, or otherwise make some adapter for them. None of that is justified, imo. I think it's better to simply install multiple 20A lines, which can be improved by derating them.
... a 15 amp circuit uses 14 gauge wire,
20 amps 12 gauge, and 30 amp 10 gauge.
Not necessarily. There are variables such as the length of the run and whether the lines are in conduit, and there can be advantages to derating the line. If you're in the US, always check local code as well as NEC.
My listening room is in a house completed in 2005, with a main disconnect panel outside serving one subpanel upstairs (where my listening room is) and another serving the downstairs. The listening room has one 15-amp circuit for lights and a separate 20-amp for the convenience outlets; I was able to move its breaker to the top of the subpanel by switching wires with another 20-amp circuit. Various finagling ensured that the audio equipment is the only thing on that circuit, although there are still a few unused convenience outlets on it.
The wife's out so I just tried millercarbon's experiment of shutting off all the other breakers in the subpanel, and am pleased and disappointed at the result.
I'm pleased because it indicates that shutting down the other circuits improves the sound, even though there was nothing but a few wall warts drawing current on them at the moment.
I'm disappointed because it means I'll have to figure out some way to run new cable from the subpanel on one side of the building to the outlets on the other, without benefit of attic access. Conduit on the outside of the building would not gain spousal aesthetic approval.
One question: Do unused outlets on the circuit detract from sound quality somehow?
AC power is a funny bugger and it helps to understand how “noise”
gets onto the line. Basically noise are
tiny “spikes” imprinted onto the sinusoidal AC wave from various sources. Use of a scope can show this. I have a Flintstone era Tektronix tube scope
which I use and shows this clearly. Some
of the worst offenders in residential are motors (with brushes such as vacuum
cleaners), compact fluorescent lamps (the self-contained pigtail type which can
cause over 100% harmonic distortion on the neutral) and any electronic device
which requires a large inrush current.
Also remember that most “noise” is running on the utility lines
themselves due to harmonics imparted from various sources mostly large motors.
A dedicated line may help and the use of hospital grade
aluminum clad MC cable may help due to the sheath acting as a shield against
RF. IG hospital grade MC cable uses a second ground (green with yellow stripe) and
with the use of an IG receptacle may eliminate some noise off of the line. This is used for sensitive hospital equipment
located in ER’s, ICU’s, CCU’s etc. The extra ground wire is connected to a separate
isolated bus bar inside of the electrical panel which is then connected to the
ground bus.
A residential whole house TVSS (transient voltage surge suppressor)
will eliminate some noise, protect sensitive electronic equipment, not costly, easy
to install and only requires two spare circuit breaker spaces and a dedicated
twenty ampere two pole CB in an electrical panel. An isolation transformer (1:1 ratio) connected
to your equipment may also help on a dedicated line by isolating both the hot and
neutral lines from the utility but the ground will not necessarily be isolated.
An isolation transformer is rated in Volt
Amps (not watts) and multiplying the voltage times the required amperage will
give a good estimate of the size needed (120v x20A=2.4kVA) but will not take
into account the small losses due to coil efficiency (power factor).
Unless your equipment requires it and you have an extreme
case, I cannot see why anything larger that a 20 ampere 120 -volt dedicated
line would be necessary using the above methods. Of course some experimentation will be needed
to get it to satisfaction. Remember that
most equipment and utility grids are 60 to 80 years old and modern upgrades to
generating, transmission and distribution have not taken place mostly due to exorbitant
cost. Utilities are required to provide
power but not necessarily clean power. (My
background is an EE degree from PSU some 40 years ago, am a licensed electrician
and worked with many local hospitals and utilities in design build). Hopefully this will shed some light on power
line carrier noise.
Here is an older white paper for a circuit breaker. The trip curve/requirements for current manufactured Thermal-Magnetic (T-M) breaker are still the same.
Note you can continuously load a T-M breaker to 100% of its’ handle rating and it will not trip if it is operating at its’ designed specs. (Continuous is defined as three hours or more).
RE: The comment about 240 volts and a step down transformer. I ran 10 gauge wiring from a 30 amp 240 volt breaker, then split pairs of 110 volt outlets to run half my system on each leg, giving 120 volts per leg, and 30 amps of current. It is a lot cheaper, but if I sell my house, I will dismantle the circuit to protect the innocent.
You make some good points, but you are mistaken about lights and outlets being on the same circuit (breaker), unless your house was built before the 1960's (or against code). I use a dedicated 30 amp line to power my system, and it works great. For those of you who want to test a dedicated circuit of 20 amps, at least before shelling out a lot of money for electricians, etc., get a good 20 amp extension cord and run it from a dining room, kitchen, or preferably from a dedicated clothes washer outlet to your system. BTW, a 15 amp circuit uses 14 gauge wire, 20 amps 12 gauge, and 30 amp 10 gauge. Breakers blow at 75% of their rated amperage. Thus, my two 1500 watt draw Audire amps alone, need the 30 amp breaker, despite their regulated power supplies; that plus two preamps, three tuners, a CD player, and turntable.
I got you beat mc. I have my own isolation transformer on the street. The electric company forced me to have that wart on my front lawn because they were worried my workshop would dim everyone else's lights. However the reverse is also true, I am isolated from everyone else. I have five dedicated lines all 20 amp, one to each of 4 amplifiers and the fifth for the line level equipment. There is a 6th one that goes to the projector. I do not use any special kind of outlets. All the power cords are made with hospital grade plugs from 3 conductor plus shield 14 gauge cable. The shield is floated on the equipment side. All cables and signal wiring is made to exact length.
Like MC, it contains an additional grounding conductor, although with this type of cable it is permissible to use the metal jacket as the safety grounding conductor, as required with isolated ground installations.
Not exactly... The armor alone is not considered an effective equipment grounding conductor. There is a (bare aluminum bonding strip) that runs straight along side the three tightly spiral twisted insulated conductors. (The white insulated neutral conductor, the green insulated equipment grounding conductor, and the black insulated Hot conductor.)
I am not sure exactly what good is the testing that was done in the link you provided. The white paper did not address anything about a voltage that may/will be induced onto the equipment grounding conductor using the 12/3 with ground cable from the two current carrying conductors. Therein the Hot and neutral current carrying conductors. Any voltage on the equipment grounding conductor may/can cause a ground loop and hum.
It all has to do with the way the cable is designed/constructed.
Also worth noting allowing the third insulated conductor (red insulated conductor) to float above ground could have two effects. For one it may have an induced voltage placed on it from either of the hot or neutral current carrying conductors which then may induce a voltage onto the equipment grounding conductor. Second the floating above ground insulated wire may act as an antenna.
As for the use of a 3 wire + ground cable here is a quote from a white paper from Middle Atlantic Products. The Company is now owned by Legrand.
AC Power Wiring Types (cont’d)
Metal Clad (MC) is manufactured in both steel and aluminum with twisted conductors that help reduce AC magnetic fields. Although the steel jacket helps reduce AC magnetic fields, the twisting of conductors has the greatest effect on reducing these fields. Another benefit is the constant symmetry of the phase conductors with respect to the grounding conductor which greatly reduces voltage induction on the grounding wire. (NEC article:330)
Two conductor plus 1 ground MC (Metal Clad)is a good choice for Non-Isolated Ground A/V systems. MC cable contains a safety grounding conductor (wire). The three conductors in the MC cable (Line, Neutral and Ground) are uniformly twisted, reducing both induced voltages on the ground wire and radiated AC magnetic fields. The NEC article 250.118 (10)a prohibits the use of this cable for isolated ground circuits because the metal jacket is not considered a grounding conductor, and it is not rated for fault current.
Two Conductor plus 2 ground MC (Metal Clad)may be used in an Isolated Ground installation, because the cable contains two grounding conductors (one for safety ground and one for isolated ground). The conductors are twisted, but the average proximity of the hot conductor and the neutral conductor with respect to the isolated grounding conductor is not equal. Under load, this will induce a voltage along the length of the isolated ground wire, partially defeating the intent of isolation (see Ground Voltage Induction section of this paper)
Note the third paragraph. Same principals would apply for 3 conductor plus ground cable.
Though the quote is for MC (Metal Clad Cable) the same tests hold true for NM sheathed cable. (Romex is a Trade Name of NM cable).
Also note the chart on page 13 for the best type of wiring and method to use.
EDIT:
For those that think they need to use an IG (Isolated Ground) type grounding duplex receptacle.
Quote from Middle Atlantic Products white paper link above.
Armor Clad for Healthcare Facilities
(AC-HCF) Aluminum Armor Clad for Healthcare Facilities (AC-HCF) is the best choice for Isolated Ground A/V systems. Like MC, it contains an additional grounding conductor, although with this type of cable it is permissible to use the metal jacket as the safety grounding conductor, as required with isolated ground installations. The biggest benefit is that the average proximity of the hot conductor and the neutral conductor with respect to the isolated equipment grounding conductor is nearly equal, virtually eliminating ground voltage induction (GVI), even on long runs.
Steel Armor Clad for Healthcare Facilities (AC-HCF) Similar to aluminum armor clad AC-HCF, but does not address ground voltage induction as effectively as aluminum(see Ground Voltage Induction section of this paper). Two other problems are that steel clad is not readily available and is cumbersome to transport and install.
It seems to me that the first thing you should do before incorporating
any of the good suggestions mentioned above is determine if you really
have a problem that needs fixing. If you do not hear any hum, noise,
hash, RFI or other anomalies during silent passages or with the volume
turned up without a signal, spending the money on dedicated lines, power
conditioners, regenerators, etc are all solutions to a problem you
don't have.
Good advice. Well... one problem. Your RFI has to be pretty awfully bad to be heard like that. Not that it can't happen. But that's a pretty low bar. We can do better.
Once again:
RFI is radio frequency interference. Radio frequencies are everywhere. When they cross a wire, any wire- every wire- they induce a current in that wire. All our power comes to us via wires. Therefore, as a matter of pure irrefutable logic, we all have an RFI problem.
So the question is not if, but how bad? That one you can only answer for yourself by listening.
Again, here's how you do it:
Listen to some music. Flip off all non-system breakers. Listen again. The dramatic improvement is telling you the degree to which you have an RFI problem. Which you do have. Beyond a shadow of a doubt. You will hear it. *Limited time offer! You have 30 days to hear it, or your money back!
I have done a lot, yet when I repeated this test myself recently as part of a component evaluation the improvement when flipping breakers was as great as ever. Because all those wires are collecting RFI and channeling it into the system. Whether we know it or not. Whether we believe it or not. Whether we admit it or not. Its just a fact. Go and listen. You will see.
It seems to me that the first thing you should do before incorporating any of the good suggestions mentioned above is determine if you really have a problem that needs fixing. If you do not hear any hum, noise, hash, RFI or other anomalies during silent passages or with the volume turned up without a signal, spending the money on dedicated lines, power conditioners, regenerators, etc are all solutions to a problem you don't have. J.Chip
If you decide to run a dedicated line for your system, but you aren't ready to go to the lengths of Millercarbon and his step down transformer and cryogenic treatments, you can get a pretty sizable reduction in RFI simply by using 12/3 romex instead of 12/2 from the breaker box to your dedicated outlet. 12/3 has four leads, one of which remains unattached at both ends. The 12/3 comes with a full twist every 4 inches, and the twisted cable and unattached wire produce RFI shielding about 10x greater than 12/2. You can further improve the RFI shielding by using conduit, but that is more difficult to install. See this article:
Back about 20 years or so, put in two twenty amp breakers and 2 dedicated lines from breaker to stereo location. A few years later, split one off to a koi pond and greenhouse. Two years ago went solar and new panel, dropped the breakers from twenty to fifteen amps. Never had a ground problem before or after. Back in the two prong power plug days, hum and noise was a constant problem, hours chasing the source and or fix. I use two Brick Wall surge suppressors and a Monster Power HTS 5100 for sources. With or without using the Monster there is no noise, the Monster looks better than an outlet strip. I like the voltage display on the Monster and it stays constant at 120V, unless it is July & 114 degrees outside.
I rewired my entire house and installed a 20 amp dedicated line with a PS Audio outlet.A year ago I moved my system to the other side of the room,intending to do a quick rerouting of the wiring later.Still haven't gotten to it.So it's plugged into a regular outlet attached to seven other outlets and two lights.I can't hear a difference.It's actually the first outlet in the series about six feet from the breaker box.I was sure the SQ was going to suffer but it really didn't.
How to handle a dirty power source? I did it by installing a regenerator. I was amazed at the solid sound field and lack of "hearing the electricity" as I had for several years. Problem solved---consider a regenerator.
Okay so here is my rig before my rig. I am fortunate that my breaker.panel is 25' away from my system. 10 guage marine grade 1000 volt insulation wire to the monoblock amps outlet (Hubble hospital grade I may add). Then I distribute the subs and source after amps.No noise no hum no ground loop none of that exists. We don't need nuclear power plants for our HiFi systems, just common sense practices. Happy Listening Mark
Meet Mr Irony. Irony is the expression of language that means the opposite. So for example one guy actually does something and actually hears and relates this actual experience. Another guy then imagines something different and shares his imaginary experience about something he knows absolutely nothing about, seeing as he never experienced it himself. Yet proceeds to act as if his imagination is reality. Which is ironic.
Good observations Daveyf. I have lived in houses where I had dedicated lines and without, always used the same panamax conditioner surge protector and I have never noticed a difference. As long as you don’t have a lot of other things plugged into those outlets most systems will work fine. If you run mono 1.25 kw McIntosh amps or something you might need a dedicated line. Never had ground loops or noise problems. Unless you have a noise problem it’s not worth the expense as background noise is usually around 30db flipping breakers and other nonsense isn’t going to do anything you could hear except in your imagination.
Every connection is a problem. The wires themselves are a problem. Much of the noise is RFI, radio frequency interference. Radio waves are everywhere. Every radio wave that crosses a wire induces a signal in that wire. That's how radio works! The tuner tunes for the frequency and then amplifies it. Without the tuner all you have is noise. The noise that is on all our wires.
To see for yourself, simply go to your panel and flip the breakers off. This disconnects half the wires. Now go listen again. The remarkable improvement you are hearing is reduced RFI. You can confirm this by experimenting with different circuits, those with something running and those without. You will find even circuits with nothing plugged in and running are still bringing noise into the system, proving the process I just described.
So my question to you is, do I deserve a raise, or what?
@cleeds You bring up a good point...the typical convenience outlet is daisy chained to other outlets...some in different rooms. However, this is pretty easily checked, and in the instance that the daisy chain is only to one other outlet in the same room ( which is what it is in my case), then I wonder how much loss is accrued to that minimal chain. Perhaps, it might behove folks to check on the amount of additional outlets the connection is chained to...and as in my original example, if it is say to the lights as well as maybe one other convenience outlet, perhaps the need for a true dedicated line is reduced. As to keeping all the lines on the same potential, maybe a simple power strip with everything plugged into it will solve that problem?
My room started with the usual normal done to code daisy chain of outlets. This was replaced with a dedicated 120V line. This was upgraded to 4 ga 240V with stepdown transformer. This was upgraded with cryo. This was all DIY and done over time so I know what did what and by how much. Since then its all been made orders of magnitude better but unfortunately I am for now sworn to secrecy and so we will just talk about the stuff you are allowed to see. https://systems.audiogon.com/systems/8367
The biggest and most cost-effective benefit is using one dedicated line to eliminate the daisy-chain of outlet to outlet wiring that is done to code. The next worthwhile upgrade is going to 240V. But how worthwhile this is depends a lot on the length of run, how good quality step-down you get, and what it costs. Going to 240V costs nothing in terms of wire. You merely connect differently at the panel. The step-down though could be anywhere from a few hundred to a few thousand.
Anything more than a few hundred and I would say stop, forget about it, there’s better ways to spend your money. Way better. Like, you won’t believe. Word is we may have independent verification coming in a week or so. But for now you just have to take my word for it.
Those convenience outlets are typically daisy-chained to other outlets, often in different rooms. That's not the equal of a dedicated line that runs straight from the receptacle back to the service panel, especially when you're trying to keep all the grounds at the same potential.
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