Dedicated power circuits

I found some MC in my shop.  Its 1 twist every 5.25 inch.  I twist 1 twist every 2 inch.

Agree with the idea that getting rid of differential noise is best done with an isolation transformer rather than relying on AC cable twists.

One interesting article I read a long time ago suggested that a significant benefit of armored cable in general, including bare-armored-ground (BAG), was that lightning surges were carried better by the armor than the ground conductor inside due to actual skin-effect issues with high frequency strikes.  The armor seems to have performed as a very low inductance path. Can't say I noticed a big improvement in noise when I used it though.

@kingrex 

Wiring an AV room is not the same as wiring a 2 channel audio room. 

+1, I am wiring two top height channels with AQ speaker wire this week after moving them. more wires, more ways to screw up. This is like "wire surgery", careful matching of connections, wires, amps, and speakers.

Well, I typed for 1/2 an hour then stepped away and it all disappeared. 

@erik_squires Wrote:

Agree with the idea that getting rid of differential noise is best done with an isolation transformer rather than relying on AC cable twists.

No offense, but I rely on Chubby Checker for doing the twist. LOL 😁

Mike

Grrrr.  Should have written common mode noise.

@gphill. Nice Leviton receptacle for audio only $5.61 each. See below:

Mike

https://www.emisupply.com/catalog/leviton-5362w-industrial-series-extra-heavy-duty-grade-duplex-receptacle-volt-p-20373.html

it is not the end of the world, but, all lines on one leg is not accurate or necessary.

Make sure you have dedicated lines to the panel.  In other words, each hot, neutral and ground wire goes back to the panel directly and isn't shared by any other circuit.

Each piece of equipment converts the AC voltage to DC internally, and they should have adequate noise filtering internally.  Ground loops (hum) typically occurs when neutrals or hot is shared by other components and is not adequately filtered.

When the neutral has an actual voltage present over the ground level, then yes, you will have a ground loop problem.  This is why the grounding schemes within each component is very important.  You have nothing to do with that, but some designers (not typically anymore) don't design the ground schemes adequately.

You want to avoid putting components on the same legs as noise making components, like noisy lighting systems, etc.  Large motors, etc.

Most if not all adequately designed electrical home circuitry have balanced loads on each leg.  That is code.  So placing a large load on one leg unbalances the system and causes problems.

My system and many that I have helped put together for others have circuity on each leg and there is absolutely no problems at all and shouldn't be.

I'm an Electrical Engineer and also a Power Engineer (analog/digital design) for Aerospace and a Power Engineer for an Electrical Utility for over 45 years.  I design and build amplifiers, filters, etc. also.

I'm not trying to piss anyone off, but the "must be on the same leg" thing, is not accurate.  Just avoid or remove noise making equipment.

Also, I have noticed that it is a good idea to have the small signal equipment (CD player/transport, DAC, Turntable, Pre-Amp) connected to a decent power conditioner and then to a dedicated line and the amps connected directly to dedicated lines.  This is why I always recommend at least three dedicated lines and not two.

If you have more than one amp, then in my opinion, they should be on separate dedicated lines and the small signal equipment connected to the power conditioner and then to it's own dedicated line.

If you have amps that are basically arc welders, then putting them on the same leg is not a good idea electrically.  Anyway, your choice.

I try to plan for the future.  Start with one stereo amp, then yes, two dedicated lines.  But, what happens when you decide to upgrade and go mono amps???

Have fun in your goals and enjoy

@minorl +1

it is not the end of the world, but, all lines on one leg is not accurate or necessary.

Make sure you have dedicated lines to the panel.  In other words, each hot, neutral and ground wire goes back to the panel directly and isn't shared by any other circuit.

I agree 100%!​​​​​​​

Mike

I disagree with most everything Minorl says. 

Keep it all on one leg. It matters. It not about the noise. If you have a good system, say AR Ref amps and an Esoteric CD player, you will hear it.  It will be more clean and clear.  If you have a Cary SLI80, you might not hear it.  But you will still notice a 10AWG dedicated circuit vs a 12 AWG feeding the rest of the living room.  

I also have not been able to validate putting lights or motors on the same leg as audio is detrimental. The noise is also on the neutral. You can’t hide from it.  I have tried this on many systems before I gave up on it because no one ever heard it.   Make sure to use a quality dimmer such as a Lutron Maestro. That will filter most of the noise.  I do put motors on a separate leg to reduce startup voltage sag on the audio phase.

I do like a good filter. But the only one I have found to work to my satisfaction is a large Torus transformer that has everything on it. Including your modem, router and switch if you stream. I don’t like most other filters. They either collapse the sound stage or create an artificial "Black".

If you don’t want to filter your audio, you segregate your power with subpanels and you filter the noise from your house. But what are you really doing. Not much unless your off grid "Island".  And if your off grid, I am still going to suggest you put a Torus onto the circuits feeding the audio to filter the inverters high frequency noise. As well as any RF that is attaching to the power wiring. If RF is attaching to the phono cartridge, tone arm wire or case of the phono stage itself, you cant do much other than get a good phono preamp that is good at rejecting the noise and not letting it modulate into the power supply.

If you happen to have a very large estate with pools and fountains, security systems, a server farm and a high end audio system, then segregating power and filtering the noise from getting back to the audio becomes something to consider.  You probably have a dedicated utility transformer so your filtered from the street noise.  You may want PFCC attached to a subpanel feeding the motor loads.  You may want a UPS attached to the server farm and security system.  You may want critical power with battery backup for light and refers in power outages.  Most people don't have this.  They share power with 5 neighbors on one transformer.  Your getting all the noise from their dirty devices.  So trying to segregate and filter your own dirty devices is a loosing battle.  Your best option is to filter the line to the audio equipment.

I have two dedicated circuits using MC 12 AWG.  Each branch is less than 40 feet long.  One feeds the front end and one the mono amps.  Originally, I had the two breakers side by side, ie. separate legs.  Somewhere in these forums I read that it is better to have the dedicated circuits on the same leg.  So I moved one breaker one space apart from the other which puts both circuits on the same leg.  I think the stereo sounds better.  Could I discern the difference in an A/B?  I’m not sure.  

The two mono amps are pulling 740W, the front end is pulling up to 500W if everything is turned on.  That’s 10 amps on one leg.  (Same as running a microwave oven).  I have a little voltmeter plugged into one of the dedicated outlets.  It shows 120V right now and did not change when I turned everything on.  (It does not show tenths of a volt.). Right now it is cold and all three heat pumps are running.  I normally see 122V.

That’s right, I just turned my stereo on at 6AM.  I’ll listen to some morning music until the weather warms up outside.  Retired living yeah!

So the electricians are here today putting in my 3 dedicated power lines. I had a new square D QO 200 amp panel box installed with all new breakers. They also installed a 26kw standby Generac generator along with a whole house surge protector. For my new lines I’m using 10 gauge aluminum clad mc wire and eventually Hubbell 5362 outlets. I realize I could have done more, and in the end I may go with some kind of power conditioner for my front end, but for now this is going to be it. Looking forward to a better and cleaner sound.

I have Pass Labs mono amps.  Combined they pull 740 Watts at idle.  Nice little heaters.  Until I exceed the Class A bias current that wattage is constant.  I think they are Class A up to around 80 Watts if memory serves.  
My preamps and DAC use tubes so their wattage is a little higher than a typical SS setup.  The line stage and phono stage preamps pull 140 Watts each, for example. 

@gphill do whatever you fell is best for you.

I'm not trying to argue with anyone here, however, ground loops occur if there is a voltage potential between the neutral and ground wires.

The only difference between the two hots coming into a home is the phase difference in the AC legs.  However, when that AC is converted to DC the PHase difference goes completely away.

That is it.

As I mentioned previously, sometimes people would connect to a hot leg that has noisy equipment connected to it or the grounding scheme in some audio equipment was improperly designed which causes ground loop issues.

Dedicated lines have the hot, neutral and ground go back to the service panel without sharing.  All circuit neutrals tie together at the service panel and all grounds tie together at the service panel.

If the leg has noisy components (AND) the internal power supply of certain audio equipment isn't up to snuff to eliminate noise properly, then, you MAY have noise.  if the grounding scheme in a particular audio equipment isn't designed properly (star ground, etc.), then you MAY have a ground loop.

But, like I said before, connecting to two legs is okay as long as you know what is on the legs.  Connecting everything to one leg is fine as long as you don't have arc welder amps that unbalance the system (noise anyone?) by drawing too much on one leg and unbalancing the system.

This is why Refrigerators, microwaves, electric washing machines, etc. as connected as balanced loads on home systems.

But I can tell you that people that claim to hear differences between all on one leg of split leg service, didn't do A/B comparisons (kind of hard to do that) and if they did, there was something else that caused the problem. like a really noisy equipment that was on that particular leg or worse, some audio component that didn't have a properly designed ground scheme.

In older equipment you would find the signal ground (for audio) and the chassis ground was connected.  not a good idea is it?  Many people know that now but back then?  not so much.  Or there were multiple signal ground points in a circuit instead of star grounding at the same point (physically).  Literally asking for a ground loop or hum problem. Has nothing at all to do with which AC leg was used.

In my experience, I have never seen an issue with all low level components tied to a decent power conditioner and then to a dedicated line and separate amps tied to their own dedicated line.

I have however many times found ground loops by the following method.

unplug everything.  Connecting the amp and speakers together only and turn the amp on. Noise?  yes, amp is the problem.  No?  then connect the pre-amp to the amp/speaker combination.  Noise?  yes, pre-amp or (interconnect cables) is the problem.  see where I'm going with this?  

Anyway, enjoy you system.  I know you will.

 

@minorl Wow great post, thanks for that. I found that to be some of the best no nonsense AC information Ive read here. Also took a look at your system on your profile, wow again, any chance for some pics? Thx again!

It’s not hard to make the comparison between 1 leg and 2 when you have gone through multiple systems and step by step made 1 change then listened.  It makes a difference.  And anyone that is caught up on just focusing on the phase line and voltage that is regulated by the equipment power supply is missing everything going on with the neutral and ground and how those 2 play into the system.

Again, you can not hide from power line noise by selecting a phase.  The noise is on the neutral.  Unless the noise is from a 240 volt motor, in which case, it’s on both phase, so again you can not hide from it.

Yes the power supply in the equipment regulates the incoming 120 volts to something else.  But most equipment also has some connection of the equipment power supply of the signal ground that is tied to the chassis ground.  So the signal is tied to the 120 volt power grid.  I have heard it.  Others have heard it.   Just do it.  In my opinion, there is no reason to not use 1 phase.  There is 0 evidence only 1 phase causes any issues.  So why fight it?  To make a point?   If that is the only reason you are arguing, your helping nothing. 

And, people here seem to think it’s great to put metal clad cable in and tie the ground to the shield of the cable which then allows the shield to become an antenna.  Or at a minimum you have introduced a ground loop because the impedance of the shield and the copper wire are different.  And before some "Engineer" gets on a rampage, let me say I have removed more than one annoyingly loud ground loop by eliminating 3 wire MC and replacing it with Romex. 

 

I don't have an engineering degree, so I don't talk as technically proficient as others.  What I have done is consult with many engineers, nuclear and NASA scientist. I have read a lot. I have taken specialized classes on grounding.   I have made alterations, observed the result, then sought out knowledge from these type people to understand why I heard what I heard.  I have also wired maybe 100 systems and have a large data base of evidence to back what works and what does not.   I will say again, putting MC into an electrical supply is a receipt for disaster unless you are very cautious.  IF you only ran 3 wire MC with a hot, neutral, ground and metal shield, you’re likely to have noise and/or ground issues.  If you ran 4 wire and don't use an isolated duplex on even 1 outlet, you may introduce ground and noise issues.  Even 4 wire MC is not a full proof way to eliminate noise.  The jacket is an antenna for RF.   It really does nothing for audio performance.   Commercial facilities use metal for fire protection.  Not because it has better performance characteristics.  Just like your house has AFCI on all the breakers.  They don't make your computer work faster or stereo sound better.  To that matter, I have sat and listened with others and you can hear an AFCI breaker as a small veil on the music.  They hinder audio playback.    But they extinguish arc fires before they propagate to the rest of the house and burn the building down.  They do a great job at that.  As do metal raceways. I have been in a room when the switch was thrown and a faulty piece of MC arched inside the cable jacket.  It was a very large boom and smoke smell.  It took a while to find the fault as the case was fully intact.  Just a small discoloration of the jacket under the flash.  No flame left the jacket where it could ignite combustible materials around it.  That is why you use metal jackets.  It’s fantastic fire protection.

The only shielding that blocks RF to any degree is a copper pipe.  No one runs wire in copper pipe.  Steel and aluminum don't really do anything towards blocking RF.  They do block EMF.  But cable management eliminates issues associated with EMF radiating from your power cable and contaminating other circuits in close proximity.  That's all metal is doing for you.  Maybe you want to run the rest of the house wiring that is in close proximity to your audio outlets in metal.  That is a good solution.

The only real block to RF is putting something such as a Torus Isolation transformer on your rack.  The best location for a isolation transformer is on the rack.  The second best is within 10 to 15 feet of the rack.  After 40 feet, you have potentially lost much of the RF noise mitigation as it has reentered the circuit again.  Metal won't keep it out.  You can coat a room with Faraday shield.  But it’s very hard to do correctly. I have heard of one audio room I want to visit and been in a commercial room that was RF treated.  The one I was in was a government building where they wanted to house sensitive equipment.  My phone still partly worked.  It was very intermittent and definitely impacted it.   But it was not 100%.  I would like to get in the audio room with my RF sniffer and see what is still there.  RF is an interesting phenomena.  In my room, my meter reads about 1700 near my rack.  Even with the equipment turned off.  It’s not my audio equipment.  Walk 24 feet out of the room and into my hallway and it reads about 70.  It’s a massive drop in only a few feet.  Directly above my audio room in a bed room the RF is around 1700.  Something about that side of the house.

 

I just came back from a work trip where a client was crying about a radio station bleeding through his speakers.  I was confident it was not my power supply, but I had to go check.  In the end through various processes of elimination an use of filtration, I was able to validate his system preamp was a mess of noise and his phono preamp was not filtering out the RF from the cartridge, tone arm, phono pre enclosure.  It is my experience through many people asking for my assistance to eliminate some sort of noise, I find the issue is the audio equipment itself that is the culprit.  I have seen it with 3 year old 40K monoblocks to brand new $20K phono stages.  I have never seen a clients noise issues emanate from a well designed electrical infrastructure using NM cable.    Having said that, I have dropped  Torus Isolation transformers on peoples racks and 2/3rds of people end up buying it.  I sold 2 out of 3 on this last trip.  There is a ton of noise on the power line. But it’s not noise you notice as a hum or radio.   It’s a hazy veil most people don't notice.  They just keep buying new gear trying to get better performance.  Once you eliminate the power line noise, the music becomes more clean and quiet.  Not black.  The room feels more calm.  Details are more present in the recordings and the bass becomes tighter and more integrated with the whole.  The music is more natural.  There is noise on your power line.  Lots of it.   But you’re doing nothing to get rid of it by wrapping a few feet of your infrastructure in steel or aluminum.  Those that say shielded wire does not matter because there are hundreds of miles of wire that are exposed to noise injection have a very valid point.

FWIW, that radio station bleeding out my clients speakers.  You won’t fix that with an isolation transformer.  You won’t fix it with any power line filter.  You might fix it with about $25K in Faraday shielding around the room.  That includes over windows, in doors, under the floor.  Everywhere.  You have to encapsulate the entire room.  Or the entire rack.  It’s possible a system set in a closed cabinet that is completely shielded will work.    And then it’s a maybe.  Better to get audio equipment that has a power supply designed to reject RF and not modulate it into the power supply of the audio equipment. 

Here is a good read.  More important, go to the References and read all of those.  I have read a lot of the materials noted in the references.

https://cdn.cableorganizer.com/old-images/midatlantic/PowerSolutions-middle-atlantic.pdf

 

In summation, if you want the best power for your audio

Ground Correctly

Use all copper panels and wiring.  This means the neutral and ground too.

Segregate power

Use an isolation transformer

Use NM #10.  Better to use twisted wire.  Better to use grain oriented twisted wire.

If your dead set on using metal encased wire, use an isolated ground system

This is a very high level list.  It lack all detail on how to set the infrastructure up properly.  It’s basically a one line.

Old White Paper. Middle Atlantic Products, Inc.

https://cdn.cableorganizer.com/old-images/midatlantic/PowerSolutions-middle-atlantic.pdf

( Rev 2b 8/7/2007 )

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Newer white Paper. Middle Atlantic Products, Inc.

Integrating Electronic Equipment and Power into Rack ...

( Rev 4b 2002-2010 )

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Page 12:

Integrating Electronic Equipment and Power into Rack Enclosures © 2002-2010 Middle Atlantic Products, Inc.

AC Power Wiring Types (cont’d)

Metal Clad (MC) is manufactured in both steel and aluminum with twisted conductors that help reduce AC magnetic fields. Although the steel jacket helps reduce AC magnetic fields, the twisting of conductors has the greatest effect on reducing these fields. Another benefit is the constant symmetry of the phase conductors with respect to the grounding conductor which greatly reduces voltage induction on the grounding wire. (NEC article: 330)

Two conductor plus 1 ground MC (Metal Clad) is a good choice for Non-Isolated Ground A/V systems. MC cable contains a safety grounding conductor (wire). The three conductors in the MC cable (Line, Neutral and Ground) are uniformly twisted, reducing both induced voltages on the ground wire and radiated AC magnetic fields. The NEC article 250.118 (10)a prohibits the use of this cable for isolated ground circuits because the metal jacket is not considered a grounding conductor, and it is not rated for fault current.

Two Conductor plus 2 ground MC (Metal Clad) may be used in an Isolated Ground installation, because the cable contains two grounding conductors (one for safety ground and one for isolated ground).

The conductors are twisted, but the average proximity of the hot conductor and the neutral conductor with respect to the isolated grounding conductor is not equal. Under load, this will induce a voltage along the length of the isolated ground wire, partially defeating the intent of isolation (see Ground Voltage Induction section of this paper).

.

Again:

Two conductor plus 1 ground MC (Metal Clad) is a good choice for Non-Isolated Ground A/V systems. MC cable contains a safety
grounding conductor (wire). The three conductors in the MC cable (Line, Neutral and Ground) are uniformly twisted, reducing both
induced voltages on the ground wire and radiated AC magnetic fields.

Read page 13. Look at the chart on page 13.

Note the far right hand side of the chart.

Arrow pointing up, Worst. Note where NM Cable is on the chart. Look at the numbers...

Arrow pointing down, BEST. Note where MC Cable is on the chart. Look at the numbers...

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Note the picture of the test board where the NM cable, (Romex) is fastened in place. Note the piece of cable is laying flat on the board. No twists, laying flat. Do you think when an electrician installs, say, 50ft to 75ft he takes care to make sure there is not any twists in the cable? Not hardly.

Look at the picture of Romex, NM cable, on page 32.

An Overview of Audio System Grounding and Interfacing

Note:

There is a magnetic “null zone” exactly midway between line conductors

What happens when the cable has twists ever so often along it’s entire length from the electrical panel to the wall outlet box? Do yo think the “null zone” exactly midway between line conductors is altered in any way?

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/ / / /

An Overview of Audio System Grounding and Interfacing

Read pages 31 thru 36.

Look at the chart on page 35. Note Aluminum MC cable beats out NM cable.

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FWIW, When I wired my dedicated 2 channel audio room in 2011 I ran two 75ft each of 10/2 NM cable. I followed best practices for the installation. 100% no twists? I doubt it.

My system is dead quiet...

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/ / / /

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I have been in a room when the switch was thrown and a faulty piece of MC arched inside the cable jacket.

Yeah and more than likely the ground fault was at the cut off point of where the metal cladding was cut and removed for make up. Was the red insulator installed properly. Was the proper tool used for cutting the metal cladding for removal from the conductors.

3/8 in. Flexible Metal Conduit (FMC) Anti-Short

 

I’ve seen a steel staple buried in the sheath of NM cable, (Romex trade Name), and short out the cable. Don’t blame the cable. Blame the guy that drove the steel staple.

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When I ran my MC cable I used metal boxes for the outlets so that the MC cable jacket is attached to the metal outlet box and the metal case of the breaker box.  I believe the metal casing of the breaker box is grounded.  I did not know that the MC cable was twisted but I am glad to know that it is.

Our neighborhood has underground utilities and I share a transformer with one neighbor.  Our house is 23 years old.  I brought home an AQ Niagara 5000 Power Conditioner from my local store (140 miles away) to try out.  I did not take it back. Whatever magic is inside of it, it makes the sound better.  Not sure if it has an Isolation transformer.  The addition of good power cords improved the blackness of the sound as well.

I have a vacuum tube preamp and I hear no noise with my ear to the tweeters.  My phono preamp generates a little tube rush noise that can be heard close to the tweeters; but that is to be expected with 66 dB of gain.  (Moving Coil preamp)

 

PS - Most linear amplifiers use power supplies which are filtered but not regulated. That is, the DC voltage at the power rails is at the mercy of the incoming voltage. A long term change in the incoming VAC will be proportionately reflected in the VDC at the rails.

All the low voltage gear (DAC, preamp, streamer, tuner, etc.) however is always filtered and regulated. A wide difference in the incoming VAC won’t affect the voltage that feeds the circuitry.

Jai, I replace MC because of ground issues.  I experience it in the field.  I really could care less about EMF issues.  You can deal with that in the field.  More EMF issues arise behind your rack than in the wall.  If you know how to run wire.   EMF is teally one of your lesser issues.  

AQ, Shunyata, Isoteck, Torus are all filters with their own technology.  And Voice.  I was pretty pissed when TAS did an article on power conditioners and failed to mention an isolation transformer.  Isolation transformers are in most every recordijg studio around the world for 2 reasons.  One they work.  2, Art kelm who specifies that work finds they work best and uses them.  I like them as I have never heard one do negative things.  Only positive.  And I can feed any amp.  I always am aware what any of the other filters are doing. 

If you hear noise out a speaker, that is ground or equipment issues.  Its not dirty power.  You deal with the issues in different ways.  

If you read Arts site, you will see he calls out metal wire and isolated grounds in his cable runs and associated panels.   There are reasons to like metal.  IMO, its not about geometry or performance.  There are other reasons to like it.   But the positives of metal can easily be overcome in NM when installed correctly with the rught materials.  .  And you don't end up with ground issues.  NM reliably works.   Filters are doing a job that addresses noise on the power line proper wiring or metal encased wire do nothing to address.

@kingrex,

Arthur Kelm said:

 . When I design a room, I try to place all electrical within steel conduit and twist the hot and neutral wires together to cut down on EMF fields.

See article below:

 

 

Kingrex said:

 

I replace MC because of ground issues. I experience it in the field. I really could care less about EMF issues. You can deal with that in the field. More EMF issues arise behind your rack than in the wall. If you know how to run wire. EMF is teally one of your lesser issues.

 

You are the first person that has raised ground issues with MC cable, at least on the audio forums I follow.

Could you expand on the problems you have experienced? If it is ground loops, it’s not the MC cable itself causing the ground problems. From what I have read is the audiophile that had MC cable installed are happy with the MC dedicated branch circuit(s).

.

 

I really could care less about EMF issues..

Where did that come from??? Not from my above post. 🤔

 

The subject matter of my post is about induced voltage by the magnetic fields generated by the Hot and Neutral current carrying conductors onto the EGC of the branch circuit wiring.

Therein, NM cable vs MC cable. If you read the two Links I provided it is proven, by measurements, MC cable does a better job of preventing the magnetic fields generated by the current carrying Hot and Neutral conductors from inducing a voltage onto the EGC.

 

FYI, The bigger the connected load on the branch circuit conductors the bigger, the greater strength, of the magnetic fields. So it would stand to reason a big hungry power amp connected to one dedicated circuit would draw more current than say a CDP on another dedicated circuit.

The EGC of the branch circuit with the power amp would be more susceptible to the chance of an induced voltage onto the EGC of an NM cable branch circuit that an MC cable branch circuit. (Especially long branch circuit runs). Therein with MC cable there would be less of chance of a difference of potential between the two EGCs of the two branch circuits than NM cable. YMMV...

 

The worst branch circuit wiring method would be to loosely pull conductors in a conduit. Worst yet is more than one dedicated circuit with conductors loosely pulled in the same conduit. Sure fired way to create ground loop hum problems.

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Interesting question. A little while back I had a project where I had to run 55 feet, 2 circuits in one pipe on the outside of a house. I spun the hot and neutral only on the 2 circuits and pulled the grounds loose in the pipe. I measured 0 mv between any of the neutral to grounds. I was quite surprised at this as I usually see maybe 5mv to 20mv. It has made me want to set up a test in my own system and measure whether it is best to leave the ground loose or twisted. I have also been told by a cable manufacturer to try and twist the ground backwards over the twisted hot and neutral. These are all things to consider.

 

Another project really surprised me when the Oyaide of about 20 foot runs was giving 72 plus mV between the ground and neutral.

As of this time, I have not had anyone tell me they are experiencing hum issues from induced mV onto the ground. That is not where I end up tracing the issue out. I have had severe hum issues when someone uses MC and goes into one box, then leaves with MC to a second box and lands a second duplex. I have seen this issue twice. I have not seen a hum issue when this is done with NM wire. But I would never advise anyone do as such. There are times when people have budgets and want to shave costs. Even 10 AWG NM is expensive. Every run is about $350 to install if the walls are open. It adds up.

I had another project very similar about 4 months ago.  2 full circuits on the outside of the house in 1 PVC pipe.  About 50 foot run.  My grain oriented twisted wire.  The customer says the system is dead quiet.

I feel there are many types of people out there.  Some are very fixed on the numbers.  They need to see measurements and they base their decisions on them.  I started as an installer.  I worked in the field and followed the plans.  Later I became an owner and designed the plans, as well as installed them.  My foundation is based more on what I find works, than what the numbers say.  That does not mean I ignore or am ignorant to the numbers.   I am aware of them, but I follow more closely what provides results in the field. 

Take for example the above readings with Oyaide.  Not the best.  But that installation was fantastic sounding.  I don't know why the numbers were so high.  But it radically changed the owners perception of how the infrastructure is installed and what/how to use the materials.  It allowed such a better sensed of understanding of his equipment he removed some filtering products from his system.  He later found other he preferred.

I don't find the measurable performance characteristics of a wire as important as what is the wire.  There are other facets of electrical infrastructure that are more impactful than what is the measured mV between the neutral and ground at the duplex.  At least as far as a home audio system is concerned.  If I were wiring a recording studio, I would probably have to re-evaluate my objectives.  With a home audio system, I want the presentation quiet, fee of grain/veil and I want it to sound as natural and close to unamplified instruments as possible.  That's my goal.  

Having said that, I do need to revisit metal encased wire.  Either MC or in a steel pipe.  I also need to revisit how I am twisting the wire.  Do either of these result in  any shift in tonality or noise I can hear.  I have even thought about full immersion cryogenic treatment.  Although a recent conversation with an audiophile I chat with frequently made me question what happens when that wire leaves the bath, then gets thrown around on a floor at a job site, manhandled and pulled into a pipe, then manipulated  in the panel and box.  Have I just cracked free and rearranged all the molecules that were altered in the freezing.   And what about over time.  There are some people saying the magic of cryo treatment goes away over time.  That is why I prefer to find the orientation of the grain from the factory and work with that.

If people want to use metal, go right ahead.  It will probably work out just fine.  Just for goodness sake, don't go from box to box with it.

All the electrical work has been done and I have 3 new dedicated 20 amp circuits wired with mc 10 gauge wire and Hubbell 5362 outlets. The wire goes from the new outlets in my den, which is where I listen to music, directly to my new square d panel box with 20 amp arc breakers. I tried it out today and everything is working as it should. Today was just casual listening to my local NPR radio station, but I can report there were no hums or ground loops just very nice sound from my Mac MR 74 tuner. 

This week I should have some chances to listen a little more critically and will report how the sound of my stereo has changed. 
 

 

@gphill congratulations regarding your three new dedicated outlets. I look forward to your comments and impressions after break-in time and some critical listening.

Kingrex said;

Interesting question. A little while back I had a project where I had to run 55 feet, 2 circuits in one pipe on the outside of a house. I spun the hot and neutral only on the 2 circuits and pulled the grounds loose in the pipe. I measured 0 mv between any of the neutral to grounds. I was quite surprised at this as I usually see maybe 5mv to 20mv. It has made me want to set up a test in my own system and measure whether it is best to leave the ground loose or twisted.

.

I spun the hot and neutral only on the 2 circuits and pulled the grounds loose in the pipe.

I’ve posted that on this forum in the past. I first read about it, here:

An Overview of Audio System Grounding and Interfacing

Look at the chart/picture on page 35. Note, Twisted L-N beat out all the others. The EGC is pulled in the conduit along side the twisted pair.

A little while back I had a project where I had to run 55 feet, 2 circuits in one pipe on the outside of a house.

Best practices dictates a true dedicated branch circuit used for sensitive equipment does not share a conduit or cable assembly with other branch circuits.

I spun the hot and neutral only on the 2 circuits and pulled the grounds loose in the pipe.

NEC only requires one EGC sized for the largest circuit breaker handle amp rating of the circuits that share the same conduit.

 

@gphill 👍

Mike

@gphill  Wonderful news, enjoy your system and the great sound.

 

 

I had a chance to do a fair amount of listening yesterday and truly believe this was a worthwhile upgrade. I have my amp on one line my preamp on one line and my sources on the other line. The sound seems cleaner with blacker backgrounds. My system has never sounded better. By the way all three lines are on the same leg. I’m not going to write a flowery review describing how much my sound has changed but it is significant. Thanks for all the help guiding me through this process, it’s greatly appreciated. 

Your experience mirrors mine, glad you also experienced an improvement!

Per post 1596

Ccomment 1.  Yes, this is where I find metal encased inwall wire to be a benefit. It is very good at rejecting EMI from surrounding wiring.  I know that is not the intent of your comment.  But its the point that EMI radiation is a real issue.  Mostly with EMI getting into signal or speaker cables.  But I am cautious of it with branch circuit to branch circuit as well.

I also find any isolation  transformer has to be located strategically to not interfere with the equipment it is powering.  That is why I prefer a wallmount in the adjacent room.

Per comment 2.  I do not find the sine wave distortion from audio equipment PS to be problematic if you run dedicated line.  That is partly why I strongly recommend multiple circuits.  I do not like a single branch with the assumption it is ridding ground loops.  PS to PS noise can become an issue on a single branch carrying all the equipment.

My comment about the issues being in the equipment itself is exactly that.  For Example, a 4 year old set of $60K monoblocks with buzz at the tweeter.  Owner gets the amps updated and all the buzz is gone.  A brand new $22K phono stage with radio coming out the speakers.  I insert 2 other phono stages and the radio is gone. I did a lot of other test to validate the issue was the phono stage.  $15K SET tube amps with bench tested measured voltage bleeding from the PS to ground creating ground issues.  I see gear itself with issues.  Not the power feeding it.  People don't want to believe their expensive purchases have defects.  But that is many times where "Issue" are traced too.

Updating your power is not about solving issues.  Its all about extracting the maximum performance from what you have.  If you have hum and buzz, its most likely the equipment, not the electrical supply.  If you have a hazy veil, soft uncontrolled bass, fatiguing sibilance, it very well may be the electrical infrastructure.

@kingrex Wrote:

I do not find the sine wave distortion from audio equipment PS to be problematic if you run dedicated line. That is partly why I strongly recommend multiple circuits. I do not like a single branch with the assumption it is ridding ground loops. PS to PS noise can become an issue on a single branch carrying all the equipment.

I completely agree! That was one of the reason why I ran four dedicated 20 amp branch circuits for audio and not one. 😎

Mike