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scott fitlin
09-28-2004, 08:31 PM
I have been in the mood to experiment, so one of the things I went and got was 2 PS Audio Power Ports, 20 amp AC receptacles with an isolated ground, custom machined brass contacts, nickel plated and highly polished, with extremely tight contact grip!

Well, they arrived today, and I pulled my rack out to access the more than 20 outlets, and of course first shut down the main breaker to this panel, and proceeded to remove two duplex 20 amp leviton receptacles, and replace them with the PS Audio Power ports.

I, as always, was very skeptical, and figuring I had just thrown away money, turned the power back on. Well, very much to my surprise, they actually make a sonic difference! The music sounds as if I removed a thin layer of grunge, and the notes are more there, for lack of a better word, but, the highs were dramatically cleaner, smoother, and more fine sounding, alot less grit in the top end! Bass stomps too! Seems tighter, with better resolution!

The two PS Audio 20 amp duplex outlets are powering my front end, which is preamp, EQ,s Xovers! So, now that I hear a big difference, I have a question for some of you guys. I am at a loss to explain why this should be, so, is the difference Im hearing due to the custom made contacts PS Audio uses, and Isolated ground? Or am I just hearing the effects of separating ground and neutral on the front end of my system? BTW, I actually have a 3 wire electrical system with a separate dedicated ground for the sound system. But of course, regular receptacles tie ground to neutral! These dont!

Does anyone think I could save a bunch of money and achieve the same thing with regular Hubbell hospital grade, isolated ground outlets?

I must have switched back and forth a dozen times, and there is definitely a difference!

www.psaudio.com

Alex Lancaster
09-29-2004, 07:02 AM
IŽd really love to get a definitive answer to this, it doenŽt make sense; Hubbel and Leviton make decent receptacles with a completely separate ground wire connection, they are cheap, maybe You could try them and tell us.

scott fitlin
09-29-2004, 10:54 AM
Hubbel custom makes the power port AC outlets for PS Audio! The contact pressure, and nickel plating, and supposedly the contacts themselves are made to PS Audio specification, is what differs from what you buy in an electrical supply house, but, still, I wonder!

Im going to install an orange hospital grade isolated ground duplex outlet and see if I get the same results!

I definitely hear a reduction of grunge, like a thin layer of dirt is gone, but I kind of feel this occurs by separating ground and neutral!

I also dont know if I would do the entire system this way, but it seems to have nice effect on the front end of my system!

Zilch
09-30-2004, 12:40 PM
Originally posted by scott fitlin
But of course, regular receptacles tie ground to neutral! HUH? I don't THINK so....

But your statement prompted me to check: I get no continuity between ground and neutral on several different three-prong receptacles I have checked here, old and new. Ground and neutral are connected at the PANEL, of course, per the Electrical Code, but not at the outlets.

I'll check some more. My integrity as a contractor is at stake here! :D

scott fitlin
09-30-2004, 01:02 PM
Neutral and ground ARE tied together. This is why one would go to the trouble of purchasing an Isolated ground receptacle at all!

In my panel the ground and neutral are not tied together, and I have a dedicated seperate ground for the system!

Besides, should you neutral burn up, the ground most definitely acts as a conduit for return current, until you have your AC wiring repaired!

In any case, these outlets clean things up a bit, thin layer of grunge, now gone, and highs are cleaner sounding too!

Zilch
09-30-2004, 01:53 PM
The little bastards are TOUGH to get apart! NO connection:

scott fitlin
09-30-2004, 02:17 PM
I was always led to believe the ground and neutral were tied together, but in any case if they are not, whats the point of paying extra money for an isolated ground receptacle, if I already have a seperate dedicated ground which nothing but the sound system uses?

I put a Hubell hospital grade orange outlet in to compare to the PS Audio outlet! There is still a difference in sound! Both are isolated grounds, but they both make the system sound different. I guess PS Audios claims are true!

I have two PS Audio power ports, and I have tried some amps plugged into it as well, but I think Ill stick to two of these powering the front end of my system, but, Zilch, do you have any logical explanations for what Im hearing, or is it my imagination and the power of suggestion?

My neighbor was just in here, and he aked me if I did anything to the system, i asked him why, he said the sound was better, at least he thought it was from what he heard the other day! I chose to tell him no I did nothing other than clean some connectors! This way Im sure he is actually hearing something, without the possibilty of suggestive power.


:confused: But I hear an improvement!

Zilch
09-30-2004, 02:49 PM
The difference in isolated ground devices is that the ground contacts are not connected to the receptacle box or conduit (if any.) Read up here. (http://www.cooperwiringdevices.com/catalog/PDF/L_CWD_Ground_Devices.pdf)

Note that the conduit is shown used as the ground connection. Conventional construction with Romex uses a ground wire instead.

In most newer residential construction, the boxes are plastic, and there is no conduit between the receptacle and the distribution panel, so the "antenna" effect is minimal. Without the conduit, you can't take advantage of its "shielding" anyway.

Refer to the latest Electrical Code to determine whether totally independent grounding, i.e., a separate lead to a different grounding rod than that serving the building electrical system, is even permitted. My reading is that it is not, for electrical safety reasons, as the earth comprises a high impedance path. The "isolated" ground must connect to the common electrical service entrance ground so that any ground fault will trip the branch circuit breaker.....

Zilch
09-30-2004, 03:39 PM
Originally posted by scott fitlin
Zilch, do you have any logical explanations for what Im hearing, or is it my imagination and the power of suggestion?Better connections can make improvements, of course. Each connection contributes to the impedance of the supply. Poor connections can themselves introduce noise into the system. However, most all gear has internal power supplies and filters. I'd expect improvement from adding an RFI filter to provide "cleaner" power, but not just from changing the receptacle type, other than the contacts being cleaner.

Oxidation is the culprit. Few know it, but, in the "olden" days, wiring was soldered where wire to wire connections occured. It's still shown on contemporary Romex boxes as a preferred technique. Now, we depend upon wire nuts installed with varying degrees of skill to make reliably gas-tight connections. Look at the connections after 20 years or so. LOL

"Do you prefer pigtails or direct connection to outlets?" It's a no-brainer to me. Daisy-chained outles on a circuit should be direct-connected. It's one reason there's TWO screws there. Look at the construction of conventional outlets above, and you'll never use the screwless connection option, either. The contact area is miniscule.

Now, for Chrissake, don't go digging into your home wiring and mess with it. No, no NO! If you think your supply circuit is a source of problems, have a licensed electrician come out and run a separate home run circuit to your system. Leave the rest alone.

Frankly, I attribute most of the perceived benefits of improvements I make to my audio systems to placebo effect. I've never let that deter me, tho.... :p

Earl K
09-30-2004, 04:05 PM
Hi

I think most codes are pretty consistant with the need to "bond" neutral to ground. "Where" it must happen, likely changes jurisdiction to jurisdiction plus whether or not the wiring is in a commercial property ( or private and "grandfathered" - exempt ).

I've certainly found that audio is cleaner the farther the "bond" is made from the active devices - as long as both neutral & ground represent equally very low impedance paths back to earth - balance is very important here .
Bad balance ( or a high impedance path - bad connections / corrosion / etc. ) and circuit noise will "up-chuck" itself into the power supplies of the devices - and then you'll hear those contaminated supplies, one way or another .

<. Earl K

scott fitlin
09-30-2004, 05:11 PM
My bond is at the mains, at least 40 feet from where the systems AC panel is, in NYC, only one bond connection allowed!

However, the PS Audio outlet seems to make my front end cleaner allowing greater transparency! And I wired a hospital grade outlet into another quad box, so I could compare! ( I do know what Im doing, so not to worry ) And still I think I hear a difference! definitely a difference from regular 20 amp receptacles, thats for sure!

Whatever it is, I like it!

My electrical system here in my buisiness is very good, and well put together! All my panels are laced, everything is Square D, and in particular, the run to the sound systems panel has a tap directly off a 400 amp leg, with NO splices! lug to breaker, breaker to panel, and NO shared neutrals either! I had a power quality analysis done two years ago, and one thing they did was measure the grounds resistance with an ultra accurate meter! 2 tenths of an ohm resistance, very negligible, if there was perhaps an ohm, maybe 2 ohms, then there is a problem! Ill attribute the 2 tenths of an ohm to the resistance of the wire itself! My voltage is stable, and runs at a consisitent 60Hz, no problems there! And considering how much electrically powered things are in this building, 36 DC motors for the bumper cars and their brushes, the 60 tons of air conditioning, and all the electronic arcade games, as well as some vintage electro-mechanical arcade devices, the signs, and interior lighting effects, the rooms 40 high output flourescents, my power is fairly clean! very little harmonics on the lines, no excessive amperage showing on the neutral.

Now that the PS Audio receptacles are installed, Ill just leave them alone, and forget they are there, and enjoy the music. But I do hear a difference, and still it puzzles me!

Zilch
09-30-2004, 05:27 PM
Bumper cars AND arcade games?

SO, when's the Lansing Heritage Forum annual convention?

:rockon1: :bouncy:

scott fitlin
09-30-2004, 05:36 PM
When i reopen

Rudy Kleimann
04-23-2006, 03:39 PM
I don't often speak up on this forum, but I can shed some light on this subject -both in theory and extensive experience. Sorry to be long-winded, but bear with me.:blah:

My background as an Audiophile since 1978, Electronics hobbyist/fanatic since age 6, Musician since age 8, an installer of Electronic navigation and communication equipment growing up in My families' boat dealership, a Commercial Electrical Contractor since 1990, Live Sound Engineer for the last 7 years, and a custom audio/video/communication/data/surge and noise suppression system installer in custom homes, have taught me quite a few lessons.

First off, regarding the neutral and ground: The ONLY place your neutral and ground should ever be directly connected is at the FIRST POINT OF NEW ELECTRICAL SERVICE. This is defined as the Service Entrance to your power Source, i.e., The first electrical panel after the electric meter or the transformer inside your business or residence that provides power to that panel. After that, neutral and ground never see each other again UNLESS the power is fed through another transformer, where the neutral is bonded to ground to keep the neutral from "floating" away from 0 volts and keeping the power legs at the proper 120 (or 208 or 277) volts with respect to ground and neutral.

That is why your neutral SHOULD read ZERO volts with respect to ground at any point within your electrical system.

The reality is that wire has resistance (albeit small); and wire connections and joints (splices) are the devils' advocate in the form of corrosion and small/weak contact at the connection points. This means that voltage to ground will always be something besides 0volts (neutral) and 120volts (line) when there is current flow feeding a connected load. The bigger the wire and the shorter the length of it, and the cleaner and tighter the connections, the better. Also, the less connections (joints) in the circuit the better. Most electrical problems or failures are a result of failure of the connection or contact point (relays and switches).

I learned this at an early age: try powering everything with 12 volts DC and using it in a boat in salt-water. It takes heavy-gauge wire and clean, corrosion-free connections to get things done in this environment. That, and a lot of maintenance and troubleshooting as time goes by.

It is important to understand that grounding should be done in what is refered to as a "star" pattern: all grounding and grounded (neutral) conductors should come together at ONE POINT ONLY. Anything else constitutes a ground loop condition which, due to the resistance of the wire itself and the different path lengths/resistances, creates either a souce for hum and noise or an antenna to pick it up, inducing noise into the electrical system.

Isolated ground electrical receptacles differ from normal receptacles in only one aspect: the ground pin contact is NOT CONNECTED to the metal mounting straps that secures the receptacle to the box it is mounted to. That's it. As Zilch pointed out, homes are usually wired with romex and boxes are plastic. The frame of the house is wood. No path to ground except through the grounding conductor in the romex, which only sees ground (or neutral) at the aforementioned first point of new electrical service.

In commercial buildings, where the wiring is inside metal boxes connected with metal conduit and usually in a metal-stud wall in a metal frame structure, the "antenna effect" of these multiple ground paths can be a real problem for sensitive electronics dealing in low-level signals that require a lot of amplification. The copper ground wire is considered the only reliable low impedance path to gound, but certainly not the only one. This is particularly important when the power is run undergound in PVC plastic pipe abd pops up into a receptacle box. This is why normal receptacles have a ground connection to the metal mounting strap: the metal box must be grounded in case a short occurs inside the box or pipe, so the box and pipe will short to ground and trip the circuit breaker instead of making everything "hot" -a definite safety hazard!

In commercial electrical installations, a "Clean Power" system has several distinctions:

1: a separately-derived system, either by isolation transformer or dedicated step-down transformer from 480 to 120 volts. These are usually "K factor" transformers, which means oversized windings (for low source impedance, which equates to higher transient current capability for more stable voltage under dynamic load conditions) and extensive electrostatic and electromagnetice shielding for lower noise both airborne AND on the power leads.

2:Separate grounding systems:
1 for the building, conduits, electrical boxes, and the neutral bond
inside the transformer itself.

1 isolated ground system for the ground pins at all of the 120 volt
receptacles feeding the connected equipment. This requires the use of
isolated ground receptacles and isolated ground buss bars inside the breaker panel for the receptacle grounds only, with its' own separate heavy-gauge ground wire connected to the ground rod.

3: Often, the Electrical Engineer will specify a separate ground rod driven
at least 6 feet away from the "Dirty" ground rod used for the transformer, building steel, and the electrical raceways (i.e. transformer case, electric panel, conduits, junction boxes, etc). This utilizes the raceway system as shielding from airbone interference and noise, the "dirty" ground wiring as ground fault protection (safety), and the "clean" ground to serve primarily as a drain for noise generated or picked up by the connected equipment being powered.

There are several sources of noise that can eek into our audio and video systems traveling into or even generated within your home either over the air or on the power lines themselves:

Your neighbors' ham or CB radio (RF interference), noise traveling in on your cable TV feed as well as voltage difference between the cable ground and your electrical system ground, electric motors in or outside of your own electrical system (commutator brush arcing noise) , ignition systems on engines, electrical arcs in switches and contactors as they open or close, Neon, flourescent, or HID lighting, your own audio equipment (digital and analog), microwave ovens, and of course your PC.

What you need from your electrical grounding system is a path to ground for ground faults (electrical shorts); what you want is a low-impedance drain for noise.

What you want from your electrical power circuit is clean 120 volt, 60 Hz sine wave power with no noise on top of it.

The importance of tight connections with no oxidation on the contact surfaces cannot be overstressed. This is where hospital-grade receptacles play a role. Instead of brass contacts with relatively weak contact pressure in the cord socket and the wiring points, Hospital-Grade recepts use heavy spring pressure in the socket spring, and all contact points are plated with chrome or rhodium.

Years ago, I was called out to install a new Electrical Panel and address an interference issue. The customer was a retired Audio and Computer Engineer, and had over $25,000 in Audio/Video equipment. He had just bought the home, and FHA financing required a Main breaker or "other means of Main disconnect" and his panel had no Main CB. The symptoms were hum in the audio, "herringbone" interference waving across the TV screen, and a strange "dancing dots" phenomenon on TV with the computer on in a room on the opposite side of the house.
I traced the problem to the neutral bar in the Breaker panel It measured 8 volts with respect to the ground rod itself. The culprit was corrision and oxidation, especially at the panels' ground wire at ground rod itself. New fresh connections on bright, shiny copper eliminated the video noise, but the hum persisted.

The incoming cable TV shield measured 300 millivolts to ground. New cable ends didn't help much. I tried a trick I had learned: a 75ohm>300ohm "balun" transformer on the cable connection to his TV, and the hum disappeared. This works by isolating the cable ground from the audio/video equipment ground. New cable installed by the company from their distribution box to his house eliminated the problem. The new Electrical panel and the requisite renewing of all the electrical connections within it further improved the sound and picture quality.

Years later, three dedicated 20 amp circuits with oversized (#8AWG) wire from the panel to his living room (only 30 feet of wire) and separate neutrals for each hot were installed and a main surge/noise suppression system installed in the electrical panel yielded great benefits in terms of lowered noise floor, better/more solid imaging, and more dynamic impact on transients. Nothing mysterious to me: just a cleaner more stable power source with better transient current available through the heavier wiring.


When it comes to devices such as this PS Audio item, You are benefitting from the Hospital-grade receptacles, as well as extensive noise filtering of the hot and the neutral conductors to ground. It still depends on good integrity of the Electrical grounding system and low resistance in all of the wiring.

It is possible that under such circumstances as I outlined above, an outboard device such as the PS Audio item may provide little or no improvement. Some of these devices can actually hurt by limiting the maximum transient current flow to your power-hungry amplifiers and voltage-sensitive equipment with meager and/or poorly regulated power supplies.

hapy._.face
04-23-2006, 04:05 PM
Since most panels will tie in the ground and neutral on a shared bus with the true ground wire (solid copper core) exiting the house and buried deep in the ground (get it? ground?)- I always wondered what (if any) benefit would come from running a TRUE isolated ground line for your dedicated receptacle?

...from the receptacle- run a dedicated copper core wire right through the walls and to the outside on a rod and drive it a good 6' in the dirt.

Phil H
04-23-2006, 06:09 PM
Since most panels will tie in the ground and neutral on a shared bus with the true ground wire (solid copper core) exiting the house and buried deep in the ground (get it? ground?)- I always wondered what (if any) benefit would come from running a TRUE isolated ground line for your dedicated receptacle?

...from the receptacle- run a dedictaed copper core wire right through the walls and to the outside on a rod and drive it a good 6' in the dirt.
You need the neutral attached to the the ground at the panel so the breaker blows. Otherwise, this can happen.
http://www.codecheck.com/images/ElectrocutionBen450px.gif
Image from http://www.codecheck.com

hapy._.face
04-23-2006, 06:17 PM
You need the neutral attached to the the ground at the panel so the breaker blows. Otherwise, this can happen.

Not according to the NEC. A quote:

'The NEC says the insulated equipment grounding conductor for an IGR may originate at the neutral point of the power source, and it may pass through boxes and panelboards without termination, but neither configuration is required [Secs. 250-96(b), 250-146(d), 250-148 Exception, and 384-20 Exception].
The NEC does not require you to run the insulated equipment grounding conductor for an IGR back to the neutral point of the power source. In some cases, running it to this point would be too difficult, impractical, or expensive. Thus, the typical grounding termination point for an IGR in an existing facility is the equipment grounding terminal at the panelboard that supplied the circuit.
Per the Code, the grounding terminal for an IGR could terminate to the metal outlet box that contains it. The NEC doesn't dictate where you terminate the grounding terminal for an IGR — just that you terminate to an effective fault current path. Nor does the NEC require each IGR to be on its own dedicated branch circuit.'


IGR= Isolated Ground Receptacle

Zilch
04-23-2006, 07:21 PM
I always wondered what (if any) benefit would come from running a TRUE isolated ground line for your dedicated receptacle?

...from the receptacle- run a dedicated copper core wire right through the walls and to the outside on a rod and drive it a good 6' in the dirt.Bad idea. It would be at different ground potential than the electrical system ground.

Dirt is high impedance (relatively speaking). :p

Phil H
04-23-2006, 10:53 PM
Not according to the NEC. A quote:

'The NEC says the insulated equipment grounding conductor for an IGR may originate at the neutral point of the power source, and it may pass through boxes and panelboards without termination, but neither configuration is required . . .
The NEC doesn't dictate where you terminate the grounding terminal for an IGR — just that you terminate to an effective fault current path. Nor does the NEC require each IGR to be on its own dedicated branch circuit.'


IGR= Isolated Ground ReceptacleYes, the NEC allows the isolated ground to pass through boxes, panels, etc. When I made that statement, I was not very specific and did not say which panel because it may pass through panels unlike a typical grounding conductor. But, your idea of a seperate ground rod does not provide an effective fault current path. The ground rod does not help with ground faults occuring in the premise.

NEC 250.2 Definitions
Efffective Ground-Fault Path. An intentionally constructed, permanent, low-impedance, electrically conductive path designed and intended to carry current under ground fault conditions from the point of ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device or ground fault detectors on high impedance grounded system
Ground Fault. An unintentional, electrically conducting connection between an ungrounded conductor of an electrical circuit and the normally non-current-carying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth.

From 250.4(a)
(1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher voltage lines and that will stabilize the voltage to earth to earth during normal operation."
(4)Effective Ground Fault Path . . .the earth shall not be considered an effective ground-fault path.

I hope Rudy responds to your inquiries because he is much more qualified than I am to answer this question. For instance, I don't think you are allowed to terminate an equipment grounding conductor on the the grounded electode conductor or the electrode. But, I do not know.

Edit: Also the section 250.146 on isolated receptacles that you mentioned says "the receptacle grounding terminal shall be grounded by an insulated equipment grounding conductor run with the circuit conductors."

hapy._.face
04-24-2006, 05:27 AM
I thought the concept behind isolated ground was to actually isolate the ground from the nuetral. Maybe grounding it independantly isn't advised; However, hooking it up with the nuetral on the same bus doesn't make sense to me- why is it called an isolated ground if you tie them together? It seems that you would get EMI and that sort of undermines the concept of audio grade receptacles. Also, in the hospitols- isolated grounds keep the ground away from the nuetral so that there is no interference with sensitive life support equipment. Right? Enlighten me, please...

SteveW
04-24-2006, 07:06 AM
Rudy, excellent reply - thank you for your input. Is it possible that Scott's improvement is the result of a higher signal-to-noise ratio due to less resistance to ground. Less current on the ground loops? Sounds to me like balanced power would be huge for his application. What do you think?

Zilch
04-24-2006, 11:13 AM
I thought the concept behind isolated ground was to actually isolate the ground from the nuetral. Enlighten me, please...Read up the link I posted at #8. Grounds are always kept isolated from the neutrals, except at the service entrance, where they are always connected.

"Isolated" grounds merely means they are not also connected to receptacle boxes, conduits, etc., as Rudy reiterated above....

hapy._.face
04-24-2006, 04:43 PM
"Isolated" grounds merely means they are not also connected to receptacle boxes, conduits, etc., as Rudy reiterated above....


OK. Thank you.

So, armed with this information- (I am dangerous :D ) It would appear that from this information:

The NEC does not require you to run the insulated equipment grounding conductor for an IGR back to the neutral point of the power source. In some cases, running it to this point would be too difficult, impractical, or expensive. Thus, the typical grounding termination point for an IGR in an existing facility is the equipment grounding terminal at the panelboard that supplied the circuit.


....an audiophile receptacle would benefit from a dedicated subpanel. Correct?

Zilch
04-24-2006, 05:05 PM
....an audiophile receptacle would benefit from a dedicated subpanel. Correct?Nope. Just more connections, circuit breakers, etc. in the path.

Have a licensed electrician run a dedicated circuit from the main panel, or several, if the need is compelling....

hapy._.face
04-24-2006, 05:14 PM
Nope. Just more connections, circuit breakers, etc. in the path.

Have a licensed electrician run a dedicated circuit from the main panel, or several, if the need is compelling........

Hey- easy now! :p

I have a master electrian here that says otherwise.

A dedicated circuit would get me a subpanel, too. The cool thing about a dedicated subpanel is that according to the NEC- I don't have to run my ground back to the main panel for the IGR. Therefore- less EMI, etc.

Zilch
04-24-2006, 05:24 PM
Uhmmm, ground in the subpanel comes from the main panel, just like everything else....

Rudy Kleimann
04-24-2006, 07:48 PM
Hey- easy now! :p

A dedicated circuit would get me a subpanel, too. The cool thing about a dedicated subpanel is that according to the NEC- I don't have to run my ground back to the main panel. Therefore- less EMI, etc.

The big wire feeding the sub-panel right there beside the sound system would help things out a lot too, as I will explain below. However, I believe you DO have to tie the sub-panel ground to the primary source ground. I think you can drive a secondary ground rod and connect it to the sub-panel ground buss (I'll have to check the latest NEC Code Book to be absolutely sure), and that would give you a better, cleaner ground for noise-dissipation purposes. you can also drive multiple ground rods and bond them all together to lower the impedance to earth.

But never, never, NEVER- bond the neutral to the ground in that sub-panel.

The idea of the IGR is to have a direct, low impedance (resistance) path to the system ground and to remove other high-impedance conductors, like the conduit, junction box, metal-stud walls, and steel structure sitting on/in concrete from having any connection to the grounding system. The metal has lower conductivity than copper, and may have a poor path to ground. This means it can act like an antenna, picking up EMI or even emitting EMI from currents passing through it which only "dirties up" the ground connection at the point where a "normal" receptacle mounts to the j-box, often 100 feet or more away from the ground rod. The resistance of the ground wire itself becomes a factor here. If you are trying to "drain away" noise that exists in the steel conduits, j-box, metal studs. and building steel that measures 200 millivolts through your ground wire,what will end up happening is that your nice little preamps' metal case will be getting some of that "building noise" imposed upon it too, radiating that noise into the sensitive circuitry carrying or amplifying your beloved music. That is not what you want from your audio component. An Isolated ground receptacle would be grounding and draining away only the noise coming from your audio components, be it from inside that preamp or from the stray magnetic field or digital switching noise generated by the TV, DVD/CD player, or power amp transformer (to name a few examples).

In wood homes with non-metallic j-boxes and wiring raceways (Romex instead of conduit), the IG receptacle in the wall is a moot point.

The things to concentrate on in any case are:

Tight, clean connections, on the hot, neutral, and especially on the grounding system, with as few joints (splices) as possible from the receptacle all the way back to the ground rod.

Wrap the wire around the screw on the receptacle. NEVER use that cheesy spring-loaded rear wiring hole on the cheapo residential-grade receptacle for the hot or neutral. Better-yet, use commercial Specification-Grade, or hospital-grade receptacles instead.

A direct, dedicated ground wire straight from the power receptacle to the ground buss, with nothing else connected to it except the receptacle.

Bigger conductors, especially for longer wire runs.

Noise suppression on the incoming power and at offending equipment running on the electrical system.

Ensure that all the metal cases of the audio components are properly grounded.

Relocation of sensitive, high-gain circuits (preamps, tuners, etc.) away from interference-producing gear (power amplifier transformers, digital audio/video gear, etc)

Elimination/removal/replacement of audio cabling that creates ground loops among the connected components.

A circuit run (hot and neutral or hot and hot, whatever the case may be) of #12AWG copper 90 feet long has enough resistance to cause a 5% voltage drop at the receptacle if the load requires 20 amperes of current. This means 120 volts drops to 114 volts at the receptacle when the connected equipment draws 20 amps. 5% is the maximum allowable per the NEC how many homes violsate this? Ever see the lights dim when you turn on that 1800 watt (15 amps at 120 volts) hair dryer in the bathroom?

With 5% voltage drop at the receptacle, the neutral would have 3V with respect to ground (hardly neutral at this point:blink: ) and the hot would have 117V, with 114volts between them. The other three volts would be lost along the length of the wire due to the wires slight resistance itself.

Upsizing to #10AWG extends this limit to about 150 feet; beyond that distance, #8AWG is required. Although the #12 wire can carry a 20 amp load without overheating, the connected equipment would suffer from a lack of available power at the end of that long run of wire.

By the same token, the ground wire would keep the voltage of the offending interference at 5% of the ungrounded voltage- 200 millivolts ungrounded is still 10 millivolts at the receptacle -with the ground wire attached!

Bear this in mind: if a signal level of 1Volt from your preamp will drive your amplifier to full power and create a sound pressure level of 120dB, then you can hear down to +/- 120dB softer than that. Following the rule that 20dB=voltage change of 10:1, then 1 microvolt at the amps' output is our lower threshold of hearing sensitivity. Pretty tiny. An SPL of 40dB would be produced by 100 microvolts to the loudspeaker, be it signal or noise(or hum).:hmm: And that would only be an S/N of 80dB. We all know we can hear that.

A typical amplifier multiplies the incoming signal by 35-40dB, meaning the same signal (or noise) that produces 40dB SPL is only around 1 microvolt presented to the amplifiers' input.

A good FM tuner can tune in a station whose radio waves generate less than 1 microvolt on an FM antenna feeding it. Phono cartridges, particularly moving coils, generate miniscule voltage signals too. And then there are microphones... These tiny signals need a lot of amplification to get them up to a level high enough to drive the power amp.

When you think about it, isn't it amazing that we don't have worse problems with noise and interference in our audio systems?

hapy._.face
04-25-2006, 06:42 AM
Thank you Rudy- very informative!

This is exactly what I was referring to, but you said it best:



I think you can drive a secondary ground rod and connect it to the sub-panel ground buss (I'll have to check the latest NEC Code Book to be absolutely sure), and that would give you a better, cleaner ground for noise-dissipation purposes. you can also drive multiple ground rods and bond them all together to lower the impedance to earth.



...it's also consistant with what my electrician buddy says. He also says that is exactly the way life support systems are set up in hospitals.

I think using the PS audio ports (or any high quality IGR) under this set up will yield even better results.

Take care

herki the cat
01-31-2010, 07:16 PM
[Revision # 2] to my reply:

[quote __long gone__"hapy._.face;108233"] ="Since most panels will tie in the ground and neutral on a shared bus with the true ground wire (solid copper core) exiting the house and buried deep in the ground (get it? ground?). I always wondered what (if any) benefit would come from running a "true ground wire (solid copper core) exiting the house buried deep in the ground for your dedicated outlet." From the receptacle- run a dedictaed copper core wire right through the walls and to the outside on a rod and drive it a good 6' in the dirt. [quote/]

To begin with "Isolated ground receptical terminology" applies 'only" to duplex outlets with ground lug floating and not connected to the metal brackets of the duplex outlet. Ce Tout.

This subject of secondary, add on, ground stakes resurfaces from time to time. Forum Member: neanderthal (http://audioheritage.org/vbulletin/member.php?u=6444) , 4350A,L-220,L-150A sometime back, posted his experience installing a "secondary dedicated grounding system" in his home complete with pictures. For the benefit of those new to this subject, here is what i learned from my local Citi Code experts, some 60 yeas ago.

"Underwriters Laboratories & the NEC Codes do not permit a voltage differential between "isolated ground" and the AC power intrance panel neutral & ground bus", which around here is grounded to some sixty feet of one inch copper pipe buried underground, terminating at the street in the city water mains.

Be aware that the AC power cord connector "third pin"green wire" ground is strictly a "personel safety ground" connected only to the metal cabinet or metal chassis of each audio system component. RCA signal interconnect recepticals should be insulated from the chassis and metal cabinets to prevent ground loops and other problems. Some equipments also use a very high value "static drain" resistor between the metal cabinets and the signal low side circuit bus.

Since "(6) milliamps,efficiently coupled like in a bath tub to a human being is leathal," Underwriters limits the total allowed current to (5) milliamperes maximum of all ground currents dumped into this green safety wire from any source, including AC power filters, surge supressors, etc. Note that some prestigious manufacturers use power filters with .05 mfd capacitors connected from the 120 volt AC high side to the equipment enclosure, which in case of enclosure grounding defects, results in charging the enclosure with 120 volts AC power. __Ground loops anybody__? Consider what will hppen to an RCA interconnet cable receptical grounded to such an enclosure during loss of earth ground.

Underwiters Laboratoris & the NEC codes will allow the "dedicated seondary ground wire buried deep in the ground, "PROVIDED" , only if this grounding wire or stake is also connected to the AC power intrance panel neutral & ground with an incredibly heavy cable. Check your local Code requirements. Underwriters & the NEC codes have rigid specification concerning the grounding stake component & soil conductivity.

Cheers herky the cat

hjames
01-31-2010, 07:24 PM
FYI - Hapy_Fez is no longer a member and hasn't been here in years ...


[quote hapy._.face;108233] ="Since most panels will tie in the ground and neutral on a shared bus with the true ground wire (solid copper core) exiting the house and buried deep in the ground (get it? ground?). I always wondered what (if any) benefit would come from running a "true ground wire (solid copper core) exiting the house buried deep in the ground"[quote/]

No need to wonder about it, hapy._.face;
Cheers herky the cat