Dedicated lines: 1) use isolated grounds or not? 2) subpanel wiring?

I've perused the forum for information on dedicated lines for my audio system. Some recommend using an isolated ground (IG) in their lines, while others have not. While I'm in the process of putting together a shopping list of parts, I must also choose some audiophile duplex receptacles. Most of the well-known ones mentioned here (e.g. Oyaide, Furutech) do not seem to have a model with an IG facility. Does this make an IG somewhat of a moot point?

Secondly, I'm having my electrician also add a subpanel which will be about 25-30 ft. from the main panel. What do you recommend I use to connect the main to sub panel? 3 gauge is commonly mentioned. Should this be run in an aluminum, steel or other conduit (impractical to run it inside the walls)?

Thanks in advance for any advice you may offer. Sorry to beat a dead horse!

 

IG receptacles are used in Commercial and Industrial building branch circuit wiring systems. The idea behind their use is to prevent electrical noise that may be traveling on the metal conduits in the building from being transferred to the safety equipment contact of a regular non IG receptacle. (The electrical noise is picked up from electrical AC noise generating equipment within the building.) Seldom are IG receptacles used anymore.

The IG receptacle safety equipment ground contact is isolated from the supporting back strap of the receptacle. From the IG receptacle equipment ground terminal an insulated green equipment grounding conductor is installed in the metallic metal conduit along with the power wiring, which becomes part of the branch circuit wiring, back to the electrical panel. The insulated green wire connects to the equipment ground bar in the electrical panel. Yes connects to the equipment ground bar in the electrical panel.

So for the typical residential dwelling an IG receptacle really would serve no purpose. Especially when NM-B sheathed cable is used. (Romex is a trade name of NM-B cable)


How many branch circuits will be fed from the sub panel?

Will the electrician be pulling an electrical permit?

 

jea48
Thanks a lot for your response. It was very helpful. I'll nix the idea of isolated grounds.

I am planning on having 3 dedicated lines/circuits put in. I'm not sure if he is going to pull a permit.

Regarding the feeder from the main to subpanel: what type of conduit would you recommend? Aluminum v. steel v. other. I'm planning to use 3 gauge wire for the feeder and 10/2 Romex for the branch circuits (twisted of course).

 

Hey Wilson L. If you have a nice way of creating a nice ground connection for your stereo with a copper rod in the dirt, you might find large sonic benefits going that way with an IG receptacle instead of trying your stereo's ground to the rest of the house. If you are going to have a bunch of outlets, you might be able to do something at the panel side or create a star ground system with the duplexes. I have run an isolated ground before and the sound improvement was huge for me.

 

It's a feeder raceway. As for steel vs. aluminum your audio system won't know the difference.
As for what is used you should be having that conversation with the electrician who will be doing the job. The electrician will know what is required by local electrical codes in your area. He is also there and knows what his options are for the wiring project that will meet electrical code.

What will the feeder conductors be, copper, or aluminum?
What manufacture electrical sub panel are you using? I assume it has copper bus.

Three 20 amp dedicated branch circuits. Approximately how long will each of the dedicated Romex branch circuits be?

Why did you decide to go with a sub panel?

Be careful of twisting the Romex tightly. A slight gradual twist is ok. A radical twist will change the lay, relationship, of the bare equipment grounding conductor to that of the hot and neutral current carrying conductors. It needs to maintain its' center position between the hot and neutral conductors.

Read pages 31 through 36.
http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

As for the receptacle outlet boxes used? I personally would use plastic and not steel.

 

Dedicated isolated earth ground rods are not only dangerous they violate NEC, state, county and city, electrical codes.

The only thing that I can think of they are good for, is in the event of a ground fault condition the earth driven ground rod works great for hunting fish worms. The worms will come right up to the top of the earth surface.

Read pages 23 through 30.
http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

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Quote from Link below:

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."

Henry W. Ott

/////

Posted by Speedskater:
Dedicated Power Line Recommendations - REPRISE! »

 

Jfeldt and jea48, thanks for your responses!

Regarding your questions:

1. Feeder conduit – my electrician says the steel conduits are cheaper than aluminum so I presume there is no benefit of one over the other from a shielding or sound quality standpoint.
   
   
2. Feeder conductor – I presume these will be copper.
   
   
3. Subpanel – the electrician has used a Square D 100a panel on a previous job of a similar nature.
   
   
4. Main to subpanel distance will be about 25 feet depending on routing of the feeder.
   
   
5. Romex branch circuits will be about 10-20 feet from the subpanel to the outlets.
   
   
6. Why subpanels? – based on recommendations from Shunyata Research that if you have multiple dedicated lines, a subpanel is recommended.

Thanks for the references from Bill Whitlock. Interesting stuff.

Re: Henry Ott's no. 5 point, the "quiet ground" does not meet NEC requirements because there is no other ground from the branch circuits that returns to the main panel, only the isolated ground rod. Correct?

 

Nice thread!

What is the best way to find an exceptional electrician who will relate to the goals of an audiophile?

 

Make sure it meets code. If in case of fire, the insur co won't pay a dime.

 

What is the best way to find an exceptional electrician who will relate to the goals of an audiophile?
I contacted one of the guys on the forum who had put in dedicated lines and used his electrician (SF Bay Area). His guy already had some experience and understood some of the over-the-top audiophile request such as 10ga wire for a 20a circuit. LOL!

 

Although this is written for UK mains, it may have some interesting info.
http://www.tnt-audio.com/clinica/ground_force_zero_e.html

 

I started to go through all this a couple years ago. I had a electrician recommended to me by my realtor. He did commercial and residential wiring here in Florida, and stopped by to find out what I wanted to do. I told him what I wanted and he said okay, and would start in a few days. I asked him about a sub panel and he said "no", then I asked about heavy gauge wire and he said "no" again. I asked about separate grounding and heard "no" again. When I asked why, he said he refused to waste my money on "nonsense". He installed (1) 20 amp breaker and (2 ) 15 amp breakers along with 1 run of 12/2 and 2 runs of 14/2 wire. They run about 50' in length. He used plastic boxes, standard outlets, and precision pliers to bend the wire. I hooked everything up, turned it on, and heard nothing but music and dead silent backgrounds. I get absolutely no noise from my air conditioner, refrigerator, or any other appliances. At full volume with no source playing, my speakers are dead silent. There are no clicks, buzzes, snaps, or other household annoyances.
For my application, I couldn't be happier. And this is living where major lightning is common. Your circumstances might be different, but when an experienced professional tells me he's going to save me money when he could have charged me triple for what he did...... I'm a believer.

 

[

>>>>>>>>>>

Rule #1, never assume anything!

Square D QO only!
The QO panel has plated copper bus.

The Square D Homeline series has aluminum bus. You don't want the Homeline...

You misunderstood what Ott said. It is not a "quiet ground" by any means.

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

 

Hey thank you for posting this, very nice.

 

I don't want a common, everyday electrician who "knows it all", yet I'm not out to waste money.

 

jea48:
My question is really what is it about an isolated ground rod that makes it noncompliant with NEC rules? Is it because no other ground is used (i.e. one that returns to the main panel)? Yeah, I kinda presumed there's no such thing as a "quiet ground."

Thanks for the info on the Square D QO panels.

 

Not all electricians are created equal.


NEC, (National Electrical Code), is bare minimum standards.


Quote from Link below:

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."

National Electrical Code 90.1 Purpose: - SPGS - Surge Protective Devices & Electrical Analysis »

 

YES.

*IF*, the electrician you are working with told you he would install a dedicated isolated earth ground rod for the safety equipment ground of the sub panel and it will not be bonded, connected, to the main grounding system of the electrical service Grounding Electrode System , find another electrician. He is not a State of California Licensed Electrician.

The purpose of the safety equipment grounding conductor is to provide a low resistive path for ground fault current to return to the source, the electrical service earth connected neutral conductor. To keep it simple for the discussion of this thread the source is the electrical service electrical panel, if the main breaker is located there, or a separate enclosure that may house the electrical service main breaker.

Instead of me explaining the ground fault circuit path here just look at the diagram in the Link, page 27 and then page 29. Page 29 shows the ground fault circuit path when a dedicated isolated earth ground rod is used.
https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

Again this method is quite dangerous in the event of a ground fault condition.
The Earth is poor conductor. But it will conduct if a path is provided back to the source. The actual real source is the grounded service neutral conductor of the utility power transformer. The ground fault current is non discriminating. Any path provided it will take back to the source. It does like a less resistive path, but it really doesn't care. The closer path might be to the earth driven ground rod for the earth connection of the electrical service neutral conductor of your home. Or the earth ground rod of your neighbor house next door.

If a path is provided for the ground fault current to travel back to the source it becomes part of the circuit from the HOT conductor of the branch circuit feeding the ground fault circuit. Will the circuit breaker trip open? Depends on the amount of current in the circuit.
Simple ohms law.
I = E/R
I = current
E = voltage
R = resistance. What is the resistance of the soil?

Will the circuit breaker trip open? Depends on the soil moisture.

Dangerous? Could be if a ground fault exists, the grass is wet around the area around the ground, and a pet or person walks through the wet grass.

 

jea48,
Thanks for pointing out the pictorial on pages 27 and 29. It was a nice graphic of what might happened with an isolated ground with a ground fault condition.

Regarding twisting cables to decrease induced voltage, Whitlock's paper on Ground Loops shows that simply twisting the L-N wires together results in the lowest induced voltage. Plain NM (Romex) had an intermediate amount of induced voltage whereas random wires within a metal conduit had the worse by a factor of 1000. In real world terms, how do these findings translate to a practical application for the audiophile? Does twisting Romex or the use of aluminum MC (e.g. with Romex) provide some incremental improvement or should we just leave Romex alone?

 

Just a side word on your plans. I see you are in CA. I would be very careful about non-permitted work. The cost of the permit is usually a small part of the total job. If in the future you would ever consider selling the home, financing a mortgage, or the possibility of future renovations that require a permit; having an electrical panel that has not been inspected and permitted will be an issue. I serve on my local planning and zoning board and we regularly run into this issue where a home owner had work done then years later want to sell or do other work and they get jammed up. Since you seem concerned about the work being done right, I suggest you insist that whoever you hire pull a permit. This will also insure the work is done to safety code requirements and will avoid future issues. I do not know of any licensed electricians in my area who would install a panel as you describe without pulling a permit. Not doing so puts their license in jeopardy as well.

 

I live semi rural, and my gear is powered from a newly replaced box I bought off amazon, ran new wire and 20 amp outlets from home depot. I have a well pump running off the same box ( different circuit ) and have no noise in my system. I needed to replace the old box because it was old and used glass fuses as breakers. My point is I think separate circuit with good ground and decent outlets can achieve pretty good. quiet power ( with the help of filtered triplite power strip ) without going crazy money wise. I am NOT an electrician and am not recommending you do it without one.....just saying that I think some people spend more than is really necessary thats all.

 

EDIT:

That should read:
Dangerous? Could be if a ground fault exists, the grass is wet around the area around the ground rod, and a pet or person walks through the wet grass.

///

True. But I don't think it would be accepted by any electrical inspector if the hot and neutral wires were pre twisted then installed in a conduit. It just ain't done that way.
Now if the raceway had a continuous removable I believe the twisted pair would be code compliant. (Providing the pair is not tightly twisted together. The manufacture of the conductors may not have designed or tested the insulation covering the wires to be tightly twisted together for power applications. Same for the UL Listing.)

Over the years I have read many posts from guys saying they installed a new dedicated branch circuit or several dedicated branch circuits and were having ground loop hum problems.

Pretty much in all cases the guy had long branch circuit/s installed. Well there is the problem, right?

I have two 20 amp dedicated branch circuits that are around 75ft each. I installed 10-2 with ground NM-B sheathed cable, (Romex is a trade name of), and my system is dead quiet.

Well that doesn't make any sense does it? A few things I did when I installed the 2 cables,
At least 80% of the parallel run of the 2 cables I keep them separated from one another by at least 12" starting from the receptacle wall outlet boxes. Why? To prevent the chance of any induced voltage from being transferred from one cable to the other by the magnetic fields of the hot and neutral current carrying conductors of the 2 cables.
I also kept the parallel run cables away from any other parallel branch circuit NM-B cables. Especially lighting branch circuits.

And last but not least both cables are terminated on 20 amp circuit breakers that are fed from the same Line, leg, in the electrical panel.

So why were the other guys having ground loop hum problems?
In many cases the wrong type wiring coupled with the wrong wiring installation methods used.

In some cases a conduit was used where the branch circuit wires are loosely installed in the conduit.

In some cases more than one dedicated branch circuit were installed in the same conduit.
(A true dedicated branch circuit should never share the same conduit, or cable, with any other branch circuits. Again induced voltage.)

NM-B cables were installed side by side against one another for a long parallel distance.

Branch circuits were fed from both Lines, legs, in the electrical panel.

And some times everything was done right and the guy still had ground loop hum problems. Usually after all the conversations the guy was having ground loop hum problems before he installed the new dedicated branch circuit/s.

Like I said in a previous post, a slight gradual twist in the cable is ok. Anything more than that could change the geometry of equipment grounding conductor position between the hot and neutral conductors inside the outer sheath of the cable.

MC (Metal Clad) Aluminum armor cable.
http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheetOEM20
The hot conductor, neutral conductor, and insulated green equipment grounding conductor are held tightly against one another in a slight spiral twist the entire length of the cable.

Not trying to cut the electrician out of any work, there in money for his labor, why are you installing a Sub Panel? Other than a Shunyata Research white paper recommended it?

Do you have plenty of spare spaces in your existing main electrical panel for 3 new dedicated branch circuits fed from the same Line, leg, of the panel?

The 3 new circuits would be only be 45ft using your posted measurements.
Part of the reasons given for the use of dedicated circuits is to decouple power supplies of audio equipment from one another. Especially digital from analog.
JMHO not much decoupling going on if the branch circuits runs are short from where they are connected, fed, from the electrical panel.

Here is a post from the late Al Sekela. Al was an EE by trade.

Quote:

The main benefit of dedicated circuits is isolation. - Al Sekela

Audio equipment power supplies generate electrical noise on the AC power circuit, and any other equipment on the same circuit is exposed to this noise. Separate dedicated circuits reduce the coupling of noise among the components.

With plenty of panel space, it should be easy for your electrician to run several circuits for not much more than the cost of a single circuit. In your setup, I would have separate circuits installed for the receiver, the CD player, the video gear, and the subwoofer (four circuits total). Adding more circuits for future expansion (such as preamp and monoblocks) is cheaper at the time and more expensive later.

Audio Asylum Thread Printer »

 

All true!

That's one of the reasons I asked the OP in an earlier post if the electrician was pulling an electrical permit. Installing 3 dedicated branch circuits is one thing, installing a new power feeder and electrical load center sub panel is another.

A few things you failed to mention in your post though if a permit is pulled, if the AHJ (Authority Having Jurisdiction) in the city the OP lives in adopted the 2014 NEC edition that will dictate the dedicated branch circuit wiring method and materials/devices/equipment used in the installation to be AHJ code compliant.

First off to date no manufactured audio grade receptacles, that I know of, are listed to be used in a residential dwelling unit, as per 2014 NEC Article 406.12 Tamper-resistant Receptacles.
(A) Dwelling Units.
None of the audio grade receptacles are "Tamper-Resistant Receptacles".

So if non UL Listed Tamper-Resistant Receptacles are used the electrical inspector will red flag the job. He will also probably chew the electrician out for wasting his time.

Next issue is the branch circuit breakers used in the electrical panel to protect the new dedicated branch circuit/s NM-B cable wiring.
2014 NEC Article 210.12 Arc-Fault Circuit-Interrupter Protection.
(A) Dwelling Units.
AFCI breakers are required. (Even if the new branch circuit/s are fed from an exiting electrical panel.)

 

There's a lot to consider. I have not actually hired an electrician but interviewing several. Whether a permit is going to be pulled is unknown at this time but I can appreciate RiCat's point regarding the safety/legal/re-sale issues. I will definitely discuss this with the electrician.

Regarding the rationale behind adding a subpanel: this is again based mostly on the recommendations of the Shunyata white paper. It seems to me that installing one 3 ga feeder (main to subpanel) with shorter branch circuits of equal size and length (Romex 10-2 in my case) from a subpanel makes more sense than having three long (45-50 ft.) runs from the main panel. A number of sources report that at that length, an 8 ga may be needed with all its attendant installation problems. Yes, I still have room in my main panel but not sure if I have 3 extra ones.

Regarding the measures to minimize hum, I plan on having the branch circuits separated as jea48 and others have suggested. Also having equal lengths on the three branches circuits will minimize potential ground loop problems.

Regarding the new AHJ codes, I have not considered the "Tamper-Resistant receptacles" or the AFCI breakers. Yikes! If it comes to that (and a permit is pulled), I would install the AHJ-compliant devices and replace the receptacles with audiophile ones after the inspection. Yes, I understand the risks and it would be on me if something untoward occurred. Otherwise, why bother doing all these things if there is no gain in sound quality. I don't see any safety issues with audiophile receptacles for example. The isolated ground issue, I believe, has been answered for me - too much trouble for little gain and most of the "audiophile" receptacles (e.g. Furutech, Oyaide) don't have IG models.

 

Good points all. As to the outlets, if audio grade are the way a person wants to go then get the job done to code, permitted and signed off. Once all is good just change out the outlets. Every home owner I know has had reason to replace outlets, switches, dimmers and some fixtures. My point here is that the owner needs to get the job done right, safe and compliant.