Installation of new AC lines......best way to ground to avoid loops and noise
I plan on installing dedicated (new breaker box near stereo) lines. I already have the AC plugs and am most concerned about configuring the best grounding system. I use single ended interconnects. Any advice would be very appreciated.
The worst source of hum and main thing to avoid is plugging components into different legs. The three utility cables coming into the box are two hot leads and one utility neutral or ground wire. To this you add one earth ground. The two rows of breakers in the box, each row connects to one of the hot legs. Whichever leg you use, make sure all your system components connect to that leg. Single most important thing you can do.
The above can be done with as many circuits as you want. Next step up from this is to run only one circuit sized to power the whole system, with only the conditioner plugged into it and everything running off the conditioner. This leaves you one unconditioned outlet to plug in the occasional extra item, compare conditioned vs unconditioned power, etc.
The next step up from this is to drive an extra ground rod dedicated to the one system circuit. By this point though you are really splitting hairs or getting into a realm where details matter. Like it may make a big improvement, little or none, or maybe even be a little worse. At this level you start to discover things you never were aware of before, like some manufacturers don't even use that third ground- oh they may use a three prong plug, but that third ground one isn't connected to anything! Floating ground they call it.
Now going even beyond this you get into things like cryogenic treatment. Which if you are going to do this do it now, way less work than pulling the wire and redoing. I'll give you one guess how I know that.... and yes it is worth the trouble. Or if you're confident and knowledgeable enough you can make your own fuse of pure cryogenically treated silver wire to eliminate the crappy circuit breakers altogether. But I would never do that. Oh no. Not me. Nor should you.
Okay I will stop here and let someone else tell you all about which connection conditioners to use....
Mother earth does not posses some magical, mystical, power that sucks nasties from an audio system
Grounding Myths
From Henry W. Ott’s big new book "Electromagnetic Compatibility Engineering"
3.1.7 Grounding Myths
More myths exist relating to the field of grounding than any other area of electrical engineering. The more common of these are as follows:
1. The earth is a low-impedance path for ground current. False, the impedance of the earth is orders of magnitude greater than the impedance of a copper conductor.
2. The earth is an equipotential. False, this is clearly not true by the result of (1 above).
3. The impedance of a conductor is determined by its resistance. False, what happened to the concept of inductive reactance?
4. To operate with low noise, a circuit or system must be connected to an earth ground. False, because airplanes, satellites, cars and battery powered laptop computers all operate fine without a ground connection. As a mater of fact, an earth ground is more likely to be the cause of noise problem. More electronic system noise problems are resolved by removing (or isolating) a circuit from earth ground than by connecting it to earth ground.
5. To reduce noise, an electronic system should be connected to a separate “quiet ground” by using a separate, isolated ground rod. False, in addition to being untrue, this approach is dangerous and violates the requirements of the NEC (electrical code/rules).
6. An earth ground is unidirectional, with current only flowing into the ground. False, because current must flow in loops, any current that flows into the ground must also flow out of the ground somewhere else.
7. An isolated AC power receptacle is not grounded. False, the term “isolated” refers only to the method by which a receptacle is grounded, not if it is grounded.
8. A system designer can name ground conductors by the type of the current that they should carry (i.e., signal, power, lightning, digital, analog, quiet, noisy, etc.), and the electrons will comply and only flow in the appropriately designated conductors. Obviously false."
Right jea48. That's why I said it may or may not be better.
Right jsautter except unfortunately you have to slog through 43 pages to get to page 44 where finally they show what I clearly explained in far fewer words: plugging connected components into different outlets can cause noise. So plug all your gear into one circuit. Voila! No ground differential. No hum. Geez how hard was that?
Right jea48. That’s why I said it may or may not be better.
Right jsautter except unfortunately you have to slog through 43 pages to get to page 44 where finally they show what I clearly explained in far fewer words: plugging connected components into different outlets can cause noise. So plug all your gear into one circuit. Voila! No ground differential. No hum. Geez how hard was that?
In most cases where the building electrical branch circuit wiring is the cause of ground loop hum it is due to the type of wiring used and or the type of wiring method that was used.
I have two 20 amp branch circuits, (10-2 with ground Romex), that are 75ft each for my 2ch audio system. My audio system is dead quiet. No ground loop hum whats so ever. No difference of potential, voltage, between the two equipment grounds measured at the wall duplex outlets. Jim
In most cases where the building electrical branch circuit wiring is the cause of ground loop hum it is due to the type of wiring used and or the type of wiring method that was used.
I have two 20 amp branch circuits ... My audio system is dead quiet ... No difference of potential, voltage, between the two equipment grounds measured at the wall duplex outlets.
I’ve had similar experience. My system is complex and biamplified, so it uses a bunch of dedicated 20A lines. Each amp is on its own line, plus there are separate lines for digital and analog sources. There are no ground loops.
plug all your gear into one circuit. Voila! No ground differential. No hum. Geez how hard was that?
It’s not that simple, because you can get ground loops even if everything is running on the same circuit. That’s because ground can also flow through interconnects and if they are different types, or have different lengths or impedance, you can have different potentials in the grounds, which results in hum. In some instances, you may need to use a grounding block to eliminate the noise, such as this. But as jea48 noted, the real cause is often the building wiring scheme itself.
Another key element to good AC is the use of tight, clean connections, from the receptacle all the way back to the service panel. I have also seen breakers with bad or corroded contacts - replacing them can not only reduce noise, but can also reduce their internal resistance and improve current delivery.
The two rows of breakers in the box, each row connects to one of the hot legs.
No, this is also mistaken. Typically, the legs alternate within each row. That’s how a 240VAC circuit is wired.
Whichever leg you use, make sure all your system components connect to that leg.
This is common advice, but it’s debatable. I have my digital gear connected to a different leg than everything else in the system. It seems to sound better that way, but I wouldn’t want to have to prove that to anyone.
I’ve experimented with putting each of my amplifiers on different legs, but couldn’t detect any difference.
Leg or not. That is factually and electrically false. And, depending on how much power is drawn from your system might imbalance the electrical load.
Electricians try to balance house loads on each leg.
Also since audio equipment convers AC to DC it really doesn’t matter.
in addition,the neutral and ground run back to the panel and tie there.
In my system I run separate dedicated circuits for each amp and plug the amp directly into the outlet.
for all low level equipment I plug them into a power conditioner which is plugged into its own dedicated circuit.
a dedicated circuit is on where hot, neutral and ground are all run back to the panel. They are not shared.
Griund loops are typically ally caused by voltage imbalance causing current to flow. Typically by interconnects and or bad internal ground schemes in some poorly designed equipment.
It absolutely does not matter is all your circuits come from the same leg or not. That is factually and electrically false.
While I don’t doubt that in some and perhaps many setups it won’t matter whether the components in a system are all powered from a single leg or from both legs, I would respectfully disagree with a contention that claiming it may matter in some or many systems "is factually and electrically false."
Following are excerpts from posts I had made in a couple of past threads which dealt with this question. (I’ve edited the excerpts slightly to remove wording that is not relevant here, as well as to remove links that no longer work):
Regarding the issue of splitting the load between two AC phases ... I looked through the ExactPower paper Jim (Jea48) referenced, the relevance of which is captured in its subtitle, "A practical guide for AV designers, installers, and electricians."
As an EE with extensive background designing analog and digital circuits (not for audio) I find the paper to be authoritative and credible. Which is to be expected, considering its authors. Among them, Henry Ott is a world renowned authority on numerous aspects of electrical and electronic design. Bill Whitlock (of Jensen Transformers) is certainly no slouch either. Some excerpts from their paper:
Less than 300 microamps of ground loop current can cause hum as it flows in an unbalanced audio interconnect cable. However, harmonics of 60Hz that are generated from lighting dimmers or switch-mode power supplies sound like Buzzz mixed with a bit of Hummm and are more easily coupled by even smaller currents. Harmonics can add together when equipment is powered from different phases, so clearly there is an advantage to specifying same-phase electrical service to power the electronics systems in most cases....
Any leakage currents on the safety ground wires of split single phase load circuits fed by different phase legs will add together due to the 240V potential difference....
Power conditioners do not solve any of these common problems: Cross phase coupling (doubles hums & buzzes) .... What actually does solve them: Same phase power.
Also, regarding ground loops ... it seems to me [Almarg] that if leakage current finding its way to the chassis (and safety ground) of a given component, via stray capacitance in the power transformer, EMI/RFI filters, etc., is out of phase with leakage current in another component that it is interconnected with, inter-chassis current flow between the two components, and therefore susceptibility to ground loop-related hum and noise, will have been maximized.
Again, I don’t doubt that in some and perhaps many setups it won’t matter whether the components in a system are all powered from a single leg or from both legs. But unless the system draws unusually large amounts of current and therefore might significantly unbalance the two legs if it is powered by a single leg (and keep in mind that most systems draw considerably less current than most hairdryers), it seems to me that what Henry Ott and Bill Whitlock have to say on the matter should be considered to be definitive as to what is best practice. And certainly not alleged to be "factually and electrically false."
My two 20 amp dedicated circuits were installed by a licensed electrician, then checked by the City's Code Inspector. Why? Homeowners Insurance, City requirements, Warranty for the work, and Peace of Mind.
I'm a very senior (Old Fud) retired electrical engineer. I could have done the work, but understood my current knowledge of the Codes was not up to snuff. Inadvertent mistakes can be costly.
My two 20 amp dedicated circuits were installed by a licensed electrician, then checked by the City’s Code Inspector. Why? Homeowners Insurance, City requirements, Warranty for the work, and Peace of Mind.
I’m a very senior (Old Fud) retired electrical engineer. I could have done the work, but understood my current knowledge of the Codes was not up to snuff. Inadvertent mistakes can be costly.
Agree 100%
But in case you didn’t know the NEC (National Electrical Code) is bare minimum electrical safety code. You can exceed the bare minimum requirements of the NEC, you just can’t go below the minimum safety electrical standards, requirements, of the NEC.
National Electrical Code 90.1 Purpose:
(A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.
B) Adequacy. This Code contains provisions considered necessary for safety. Compliance therewith and proper maintenance results in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.
FPN: Hazards often occur because of overloading of wiring systems by methods or usage not in conformity with this Code. This occurs because initial wiring did not provide for increases in the use of electricity. An initial adequate installation and reasonable provisions for system changes provide for increase in the use of electricity.
(C) Intention. This Code is not intended as a design specification or instruction manual for untrained persons.
(D) Relation to Other international standards . The requirements in this Code address the fundamental principles of protection for safety contained in Section 131 of International Electrotechnical Commission Standard 60364-1, Electrical Installation of Buildings.
FPN: IEC 60364-, Section 131, contains fundamental principles of protection for safety that encompass protection against electric shock, protection against thermal effects, protection against overcurrent, protection against fault currents, and protection against overvoltage. All of these potential hazards are addressed by the requirements in this Code.
Look Closely at Section (B) Adequacy it reads as follows: "Compliance therewith and proper maintenance results in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electric use."
B) Adequacy. This Code contains provisions considered necessary for safety. Compliance therewith and proper maintenance results in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.
First you have a mighty fine 2ch audio system there.
As for your statement stating that dedicated circuits installed to feed an audio system installed in a home must be fed from both 120V Lines, Legs, is not accurate, imo. Would you please cite in the NEC where it says it.
In probably the majority of audio systems in the US and Canada the total combined load of the audio system equipment at best would add up to 8 to 12 amps continuous load at best. One 120V 15 amp branch circuit would be more than enough. Not to mention it would meet or exceed the bare minimum NEC standards. (#14awg copper wire fed from a 15 amp branch circuit breaker.) If the home owner wanted the electrician to install two 120V 20 amp dedicated circuits fed from the same Line, Leg, I see nothing in the NEC that says it would violate the the NEC.
In your case with your audio equipment I can see and would agree the ARC mono amps should be be fed from both AC Lines, Legs. Yes, to balance the two loads across both Lines of the electrical service panel. Jim
First, let me be clear that my intention is to not, I repeat not, get into arguments about the technical aspects (or non-technical) aspects of having your system wired on both voltage legs.
I am an Electrical and Electronics Engineer, well versed in amplifier/filter design and test. I am also a power Engineer and a state registered power Engineer.
I don't have the in front of me but it is safe to say that in designing home electrical circuits, the Electrician tries hard to balance the house loads on each phase so as to not overload one phase. So, air conditioners, refrigerators and equipment with large current load are balanced between the phases.
For high end audio equipment, the low level equipment isn't an issue. However, for ridiculously large class A amplifiers or some such, that is another issue altogether. If the Electrician has half a brain, he/she is going to inquire as to average load usage and try to balance that load.
This is a non-issue. What is the issue is to try to not have audio equipment on the same circuits/legs as noisy equipment, such as particular types of lighting.
Ground loops are created by potential (voltage) differences between equipment on a closed loop, which will cause current to flow in that closed loop.
AC from the panel is converted to DC in most audio equipment, so which leg it comes from is really a non-issue. As long as the ground and neutral run back to the panel and are not shared. When you share neutrals or the grounding scheme of your system or worse, of a particular piece of equipment is not well designed, that is when you have serious problems.
This is why I tell people when running dedicated lines to make sure each dedicated line consist of a hot, neutral and ground that is run directly back to the service panel with its own circuit breaker and are not shared.
So, say one has two amps and a lot of low level electronics, then ideally, you would want a minimum of three dedicated lines to the panel. One for each amp and another for the low level equipment, such as pre-amp, tuner, cd player, DAC, turn table, etc. That I recommend all low level equipment is plugged into a power conditions (tying the grounds together) and that has its own dedicated line.
My ground flow is seriously low. When I installed the dedicated lines, the ground flow dropped to dead silent. Playing with various power conditioners for the low level equipment was fun as the sound improved with better conditioners.
Again, most ground loops are caused by voltage imbalances between equipment and seriously poorly designed grounding schemes within equipment. most newer equipment has a type of star grounding schemes within the equipment.
If it isn't a loading issue on your panel, then yes, why not? go ahead and put all equipment on the same leg. But, it isn't the end of the world. That is not a ground loop problem. Also, it is quite easy to move that circuit or circuits to the other voltage leg within the panel if need be. But, I doubt it is a real concern.
Ground loops are created by potential (voltage) differences between equipment on a closed loop, which will cause current to flow in that closed loop.
We are in agreement there.
IF there is a difference of potential between the equipment grounding conductors of more than one circuit feeding audio and or video equipment, that is connected together by wire interconnects, there will be current flow through the chassis, signal ground, of the interconnect connected equipment .
No different than when a difference of potential exists between the shield on an improperly grounded CATV providers coax cable and the equipment grounding conductor of the branch circuit outlet the audio/video equipment is plugged into.
If you are concerned about ground loops, the thing to do is make sure that the equipment you use has competent grounding systems internally. Using your DVM measure from the ground of an RCA input to chassis; if you read less than 1 ohm ground loops are probable if the ground connection of the power cord is connected to the ground connection of the AC receptacle. So measure for continuity between chassis and the ground pin of the power cord.
If its not hooked up, seriously consider sending the gear back to the manufacturer for repair. This is the 21st century- people may have gotten away with that 40 years ago but its not acceptable now and oddly a bit too common in high end audio...
Also check between the ground of the output RCA; that should not be at chassis ground either.
Competent grounding of audio equipment isn’t that hard, despite the crazy amount of nuance that exists in this topic. IOW if your house AC wiring is done to code you **should** not have any problems; if you do its not the fault of the AC wiring.
Competent grounding of audio equipment isn’t that hard, despite the crazy amount of nuance that exists in this topic. IOW if your house AC wiring is done to code you **should** not have any problems; if you do its not the fault of the AC wiring.
The NEC is bare minimum electrical safety code.
From NEC Article 90.1 Purpose:
National Electrical Code 90.1 Purpose:
(A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.
B) Adequacy. This Code contains provisions considered necessary for safety. Compliance therewith and proper maintenance results in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.
The NEC could care less if a person has ground loop hum problems with their audio system. The NEC’s only concern is the AC power feeding the equipment is electrically safe to protect persons and property from an electrical hazard.
Example The NEC allows multiple branch circuits to be installed in a common conduit. Are the chances of ground loop hum greater using this type wiring method than using individual runs of 2 conductor with ground metallic armor MC cable? Yes, it is. Both type of branch circuit wiring meets the NEC. Individual runs of NM sheathed cable (Romex) installed correctly is better than using conduit with multiple single conductors pulled loosely, randomly, as is the normal installation method used by licensed electricians.
One thing about breakers besides copper ,there are silver, silver tungsten circuit breakers which are better and don’t oxidize like Copper Siemens and one other company make them20 amp.
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