Acceptable Level Ground/Earth Noise

I have a dedicated earth for my audio system ... The line runs straight to my dedicated audio room and is shared among the various audio components. I am running a Clearaudio DC preformence through an Avid Phallus phone stage...

Dedicated earth ground? As not connected to the main grounding system of the electrical service of your house?

If that is the case you have two earth connections that are not electrically connected together and therefore are not of equal ground potential. Not only is it dangerous it can cause 60 Hz hum.

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"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 that 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.

Henry W. Ott

• https://books.google.com/books?id=2-4WJKxzzigC&pg=PA119&lpg=

I am assuming the OP’s "dedicated earth" is not connected to any other grounding system in his house. Though he really didn’t say how the ground is connected to his audio equipment. Is the ground connected to the equipment ground terminal on the duplex receptacle/s that feed his audio equipment? Did he disconnect the branch circuit equipment grounding conductor from the receptacle/s? Or did he leave the branch circuit equipment grounding conductor connected to the receptacle/s and connect his "dedicated earth" directly to the chassis of the audio equipment? If he defeated the branch circuit equipment grounding conductor and replaced it with his "dedicated earth" connection it is surprising to me he has not lost any equipment due to lightning. (Lightning would/will flash over from his "dedicated earth" over to the neutral, " The Grounded Conductor", in his audio equipment as well as travel through the in wall branch circuit neutral conductor back to the electrical panel service neutral to earth again.)

Also if the branch circuit equipment grounding conductor was defeated the OP has eliminated the low resistive path of the branch circuit equipment grounding to carry ground fault current back to the source in the event of a hot to chassis fault in his audio equipment. In the event of a fault the ground fault current path will be his "dedicated earth" connection. Works great for hunting fish warms. Sucks for providing a low resistive path back to the source, the grounded service entrance neutral conductor.

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Even if the OP connected his dedicated earth connection (?) to the branch circuit/s equipment grounding conductor, making it an "Auxiliary Grounding Electrode", I would not recommend it... Even if it would/does meet NEC Code 250.54 Auxiliary Grounding Electrodes. It would only add a path for lightning to enter his house and fry who knows what besides his audio equipment.

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Mother Earth does not possess some magical mystical power that sucks nasties from an audio system.

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Guys sorry did not mention I am not based in USA and laws are not the same and not as well enforced.

Ground is ground world round.

 How ever if this is a safety issue I could easily connect the new earth to the existing setup.

Not sure what you mean. Please explain in detail. Per electrical safety code/s where you live it may be a violation to add a dedicated earth ground to your audio system, or to the grounding system of your electrical service of your home. I have read some parts of Europe the utility power company's transformer neutral conductor is connected to earth at the transformer only. An equipment grounding conductor is ran from the transformer/distribution box along with the power lines that feed the dwelling unit.  

My question remains. Is some level of hum part of an analogue setup or should it be absolutely quite?

Mine is dead quiet, and I do not have a dedicated earth ground.

For a test disconnect your "dedicated earth" connection from your audio system and then listen for the hum. Post back your results.

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I live in Pakistan and the earth supplied by our utility is useless. All houses have there own grounding sunk about 12-18 feet into the earth into a copper plate with bare copper wire coming out of the ground and providing earthing to the main distribution of the house from where this is run throughout the house.

Not that that much different from what we have here in the US. Here we basically have a bare minimum of 2 earth connections called grounding electrodes that connect to the main incoming electrical service entrance neutral conductor. The minimum depth of the electrodes must be a minimum of 8ft for a ground rod and 10ft minimum earth covered metal water pipe if provided. One other grounding electrode that is required if the house has concrete footings is a concrete encased grounding electrode. (Started sometime around 2008)

No matter how many grounding electrodes there are they all must connect to one point. The electrical service entrance neutral conductor.

Your electrical code apparently requires the grounding electrode to be installed deeper into the earth. I would imagine because your soil moisture content is less and you may not get as much rain/moisture as we do here in the US.

I have simply taken another connection point that is sunk further into the ground and which is not shared by the rest of the house.

That does nothing for the sound quality of an audio system. If anything it just adds noise. If you want added lightning protection, by installing an additional grounding electrode, connect it to the main grounding electrode system of your electrical service.

Again the mother earth does not possess some magical mystical power that sucks nasties from an audio system.

If you want a direct mains power feed for your audio equipment I would suggest you install a dedicated branch circuit from the electrical panel to an electrical receptacle outlet for your audio equipment. The new branch circuit equipment grounding conductor is also part of the branch circuit. It should connect to ground bus in the electrical panel the brach circuit is fed from.

I do have a lightning rod connected to the main earthing system.

That is a no, no, here in the US. Lightning rods do not connect to the electrical service grounding system. Lightning rods have their own driven ground rod/s. Going from memory they must not be driven near ground rods/electrodes that are connected to the electrical service entrance neutral for obvious reasons.

At the moment what I have done is takes the separate earth and connected it to the earth wire that is supplying the various resecptales that are being used in my set up.

That sounds like an Auxiliary Grounding Electrode to me. I would not recommend one.

I have also taken another wire and connected it to a copper bus bar to which the analogue equipment is grounded through individual wires such as the earth wire attached to the RCA wire plug the earth plug at the bottom of the table as well as the earth on the phono stage. All the 3 pin sockets are also grounded in the sockets as they would be normally.

Does absolutely nothing for the sound quality of your audio system. If anything it adds noise. Which you have now.

Did you try what I suggested in an earlier post. Disconnect your "dedicated earth" connection from your audio system then listen to it.

Here is a video for you to watch. It basically relates to what you have now.

https://www.youtube.com/watch?v=YuDqXFvRv94

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I did forget to mention it gets louder when I touch the tone arm so could be something else.

I have also taken another wire and connected it to a copper bus bar to which the analogue equipment is grounded through individual wires such as the earth wire attached to the RCA wire plug the earth plug at the bottom of the table as well as the earth on the phono stage. All the 3 pin sockets are also grounded in the sockets as they would be normally....

I did forget to mention it gets louder when I touch the tone arm so could be something else.

gs5556 said:

Connect that ground to where the house ground and lightning ground are connected thereby creating a star ground. This way the voltages across the ground rods will be the same in the event of a lightning strike.

gs5556,

I stand corrected. The lightning electrode system shall be connected, bonded, to the grounding electrode system of the electrical service.

Q. Please explain how I’m supposed to ground a service on a building that has a ground ring used for the lightning protection system grounding electrode?

A. If a lightning protection system is installed on a building/structure, it must be bonded to the building/structure grounding electrode system as per 250.106. The grounding electrode for a lightning protection system must not be used as the required grounding electrode system for the buildings or structures [250.60].

http://ecmweb.com/qampa/code-qa-grounding-lightning-protection-system

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Principles of Grounding of Lightning Protection Systems per NFPA 7803.

Grounding

A. There are several types of lightning grounding, used separately or in combination, as selected by the installation contractor. Ground rods, perimeter (ring) bare wire, radials, plates, and concrete (rebar) encased designs all constitute acceptable earth electrodes. The lightning grounding electrode is a dedicated part of the lightning protection system. No other ground shall be used as a lightning ground (see section 4.13.1.3).

B. Other (non-lightning) systems requiring grounding shall be integrated (bonded or connected) to the lightning ground to form a common ground potential (see section 4.14). This is to protect electrical equipment from voltage rise mismatches where separate grounds are employed. Under lightning attachment conditions, the lightning ground will function independently of any other grounds. Should electrical system grounds not be connected to the lightning ground, the overall lightning protection system will still function as designed.

http://lightningsafety.com/nlsi_lhm/grounding_principles_NFPA780.html

For the US anyway, per NFPA780 as well as NEC 250.106 and 250.60.

If my understanding is correct each grounding electrode system shall have its own grounding electrode/s. The two systems are then connected, bonded, together. I assume by a minimum #6awg copper wire. In other words lightning rods cannot be installed and directly connected to the electrical service grounding electrode system. Is that your understanding as well? 

Jim

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almarg said:

Jim (Jea48), thanks for posting the Henry Ott writeup. I’ve seen that before and I always get a chuckle out of it, especially no. 8. For others who may not be aware, Mr. Ott is one of the world’s leading authorities on grounding and various other aspects of electronic design that often tend to be mysterious even to trained EEs.

Hi Al,

I think Ott hit the nail on the head with #4.

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 that by connecting it to earth ground.

AL,

I agree with your post above about disconnecting all that earth grounding that srafi has added, connected, to his audio system. It does nothing for the SQ of his audio. If anything it adds noise. The only ground he should have connected to his audio system is the safety equipment ground.

srafi said:

I did forget to mention it gets louder when I touch the tone arm so could be something else.

To me that sounds like the tone arm is not grounded to the signal ground of the phono preamp. LOL, I’m almost hesitant to use the word grounded. Some take the word as meaning mother earth ground.

If the TT has a ground wire and srafi has it connected to the chassis of the phono preamp it could be the ground wire connection is open/broken. If that is the case there is a good chance it would be inside the TT. For a simple test he could connect a wire at the phono preamp chassis and then touch the other end of the wire to the tone arm or to the tone arm support tower. If the hum stops he has found his hum/buzz problem.

I would also check the cartridge phono wires to make the connections are good.

Jim

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@srafi,

I was searching for some information on your turntable. I ran across the owner manual and found this note.

2.2

To avoid hum noises it can be necessary to ground the bearing. For that please plug in the provided ground cable into the hole of the screw from the bearing at the bottom of the turntable.

It doesn't say were to connect the other end of the cable/wire. I would think it should connect to the phono preamp chassis ground lug/terminal.

Do you have this ground wire connected to the turntable? If so where do you have the other end connected?

Another question. What is the arm you are using on the table? What material is it made of? 

Clearaudio Performance DC Turntable owners manual.

http://clearaudio.de/_assets/_pdf/manuals/turntables/CA_Performance%20DC_E.pdf

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I did forget to mention it gets louder when I touch the tone arm so could be something else.

Is some level of hum part of an analogue setup or should it be absolutely quite?