"Ideal" power line from Service Panel

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Hello everyone.

Since I'm doing construction (remodeling) I thought this was a good place to ask this question. (that, and I couldn't find a better place!)

So, what I'm doing is reconfiguring 1/3 of my first floor to be a 'media room' which is the TV room and Stereo room (and a small office in the corner and the [upright] piano will be in here as well).

Since it is the first floor, I have full access from below to run dedicated power just for the stereo system, totally isolated from all the other electronic paraphernalia in the home.

So, here's my plan:

Dedicated 20 amp breaker in the panel (which was just fully replaced/upgraded to 200-amp service; full copper throughout and new 6 foot ground rod), across the cellar ceiling to a 20-amp floating ground outlet "Hospital outlet".

Along the way, I was thinking it might not be a bad idea to run the Romex inside a piece of copper pipe (earthed). Steel pipe is out, as it will probably become magnetized. (Correct me if I'm wrong, but this will be close to 50' run)

I also have a (HUGE) 1:1 isolation transformer/conditioner from an old computer mainframe. 20 amp input, 19.5 amp output. Perfect. The plan was/is to run into this (mounted on the wall in the basement) and out to the outlet upstairs- a very short run <6 feet.

Since the original concept, I have thought about some improvements to the design:
  • Use stranded 12-ga cable for the A/C feed, as a twisted pair in the copper pipe (as opposed to solid 12-ga Romex), with the ground running parallel (or possibly counter-wound on the outside of the twisted pair?) inside the pipe.
  • Split the A/C at the isolation transformer so only the analogue components use the "filtered" power; with all the digital components using the 'unfiltered' by-pass A/C line (this would include the DVD player and other digital equipment as well as D/A converter and CD transport) To hopefully isolate the 'digital noise' from the analogue A/C line.
So, I guess the question is: if you had this (somewhat) unique opportunity, what would you do?
 
Fro everything you need to know see:
Jim Brown, AES Committee Chair has an excellent paper on power and grounding.
This paper now has been updated and has an International Wiring Version.

See Jim Brown, Audio Systems Group:
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf

The rest of his some 50 plus papers at:
Audio Systems Group, Inc. Publications


If that's not enough see:
The Bill Whitlock of Jensen Transformers Seminar paper
http://www.jensen-transformers.com/an/generic seminar.pdf

The Jim Brown of Audio Systems Group white paper
"Power and Grounding for Audio and Audio/Video Systems"
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf

"The TRUTH" from ExactPower of Middle Atlantic Products
ExactPower(tm) - Home of the Residential Power Integrity System

or a different version of the same paper

"Power White Paper" from Middle Atlantic.com
Middle Atlantic Products - White Paper - Integrating Electronic Equipment and Power into Rack Enclosures
 
Along the way, I was thinking it might not be a bad idea to run the Romex inside a piece of copper pipe (earthed). Steel pipe is out, as it will probably become magnetized. (Correct me if I'm wrong, but this will be close to 50' run)

No advantage between copper and plastic!
It's the soft steel that does the job.
It wont get magnetized with all that AC current de-magnetizing 60 times a second.

I would rather have all the audio equipment on the same circuit.

All the ground rods (6 ft. is short) must connect together at only one place!
That place is very near the main breaker panel.
 
I don't know if any of it it could make much difference. But I might at least consider running several separate power/ground runs to several separate outlets, and maybe even a ground-only run or two, to dedicated ground terminals (for what, I don't really know).

Mainly, just make sure you install about twice as many outlets as you think you might need. And while you've got easy access to the walls, etc, you might also want to install proper wall-plate hookups for whatever else might eventually be desirable, such as audio, data, antennas, etc.

You might even want to consider a separate whole run from the pole transformer to a separate box, first. But, as I implied, considering all of the miles of junk between you and the source of the power, I don't know if any of it makes sense.

I guess you could also consider some sort of centralized power conditioning or filtering, too.

I would probably use some really-thick stranded wire/cable, for everything, maybe especially the grounds. Maybe some of the stuff they use to connect automotive starter motors would be good.
 
Thoughts:
The ExactPower & Middle Atlantic Products papers have good sections on using isolation transformers. (the 2 papers share some common pages, but each has additional stuff)
This is also a good page:
ground1.com - Power Distribution

No difference between solid and stranded wire except for ease of installation.

Twisted pair (really trio) is a good way to run power wires (even Romex).

The power company won't like the idea of running another service entrance.

I like to keep the length of AC wires between components as short as is reasonable.
 
I did a recording studio and the biggest change was breaking the neutral-ground tie using an isolation transformer with subpanel and dedicated ground rods. So much noise gets in there, as neutral is wired all the way back to the substation and then it gets tied to ground in your service.
I put an array of ground rods in, verified their impedance (as they better handle 20amp faults too!).
 
Isolation transformer does ZERO for filtering the noise in the line. The noise is mainly HF noise and that passes from primary to secondary wound by inter-wound capacity. You would need transformers with a foil of grounded copper shield between the primary and secondary to cut that capacity - usually the industrial isolation transformers don't have that.

Forget about Romax or EMT conduit. Buy some AC cable with isolated ground (IG). Or MC cable with normal ground and isolated ground. Those cables have copper conductors, twisted arround each other. Do NOT use stranded conductors - they require special termination in order to maintain good contact over years.
Installation must have isolated ground receptacles but it MUST be done corectly, as described here:
An isolated ground receptacle (IGR) can reduce electrical noise, but if installed incorrectly, it can create a dangerous installation. This receptacle differs in construction from its self-grounding counterpart. The grounding terminal for an IGR is insulated from its metal mounting yoke. This means you must connect the grounding terminal directly to an effective fault current path by an insulated equipment grounding conductor. To ensure the device you're installing is an IGR, look for the Code-required orange triangle located on the face of the receptacle.

I would go with #10AWG conductors (even if NEC allows for #12AWG) on a 20A breaker. Voltage drop (dependent of load) will be greatly minimized.
Also, any kind of "conditioners" will increase the (variable) voltage drop and they are not good for audio. Regardless what salesman say. The only thing that can be on the line is some kind of surge arrester device.

Also, in the audio center, bring two or three dedicated circuits - not sharing the neutrals and all from the same phase (breakers from the same side of the panel). Balance the panel load with consumers somwhere else in the house. Using the same phase will minimize the interferences.

You don't need other ground rods beside the one at the service entry - it is banned by the NEC (interfere with GFI receptacles functionality) and will create ground loops that could pick up hum. Neutral and ground shall be tied toghether just at the main panel.
 
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See! I knew this was the best place to ask this question!:D

Just to clarify a few things:

The ground rod I was referring to is the new one installed outside where the service enters the house. I will NOT be adding a second one. It may be 10' long (probably is if that is code requirement) as I did not see it before it was pounded in...

Isolated ground outlets will have an isolated ground; boxes are plastic.

Good call on keeping phase the same! That was something I did not consider.

Terminating the ends of the (stranded) wire won't be a problem, if that is the best way to go up to and excluding the terminations. I can work with the wire; I just need to know it is the better choice in wire for the run. If not, solid is easier to deal with for sure. If I do go solid, should I pull apart the standard Romex and strand that? I can't imagine parallel solid is the best way to go for interference rejection... (but I'm not sure, so I'm asking!)

It seems like the steel conduit is the way to go up to the transformer. On that note, this thing is a line filtering transformer for a main frame- NOT an off the shelf 1:1 transformer. It was made to 'clean up' the power for an old-*** computer. I've had it for a while. It has its own gravitational field. I think it's made of depleted Uranium. It's a bit heavy- I may need to pour a slab for it... It does make a bit of noise, so it will be below the floor of the listening room, and only the output will come up to the room.

What about the analogue/digital separate outlets? any worthwhile advantage, or should I just have a secondary line conditioner on the outlet (one for Analogue and one for digital) to provide isolation?
 
One thing i will caution is that NONE of this will pass electrical inspection if not followed to code carefully. and trying to get your local inspector to understand what your doing and why is a whole other issue. I have dealt with this in several new construction recording studios and large home theaters. Electrical inspectors don't necessarily understand star grounding, low impedance ac runs. they think its all the same. and trying to get the inspector to understand a balanced power system whooooo! yeah that was fun. it was clear to everyone including him that i knew more then he did and he got mad and pulled the electrical permit on us. we had to fight to get it back and show proof that what we were doing was safe and by the book. In the end he relented and signed it but not because he ever understood it or wanted to.

SOOOO, things like stranded wire, copper pipe etc are not going to fly past an inspector. I would suggest you speak with your local and make sure of what you are doing before you do it!

Once you get cleared...I would mount the isolation transformer as near the room as possible to keep the secondary feed as short as possible. I would also think about HOW you are going to mount the transformer to reduce hum/buzz from being transmitted into the structure. Mounting on rubber pads or isolators is recommended. and use flexible plastic conduit as well.

and in the end you haven't done anything to reduce noise or stabilize voltage so i wouldn't go too overboard here.
 
One thing i will caution is that NONE of this will pass electrical inspection if not followed to code carefully.

This is a reason I am leaning heavily toward going with rigid steel conduit with (twisted) stranded wire now. Common steel conduit is something any competent inspector will be familiar with, and anyone else working on the installation long after I am dead will understand this far better than a piece of copper pipe with wires inside! Speaking as the guy now trying to make heads or tails of the house fire waiting to happen that passes for an electrical system in my house, I can understand it from both sides of the fence. So, standard electrical service parts, used in a more careful and deliberate manner.

and trying to get your local inspector to understand what your doing and why is a whole other issue.

Another reason to use standard electrical stuff. He may not understand it, but at least he can recognize electrical conduit with wire inside going to a transformer and out to an outlet. Should be easier to swallow than some of the other ideas!


SOOOO, things like stranded wire, copper pipe etc are not going to fly past an inspector. I would suggest you speak with your local and make sure of what you are doing before you do it!

Stranded wire is used quite often (all the time in fact) in our industrial installations. Pulled through galvanized steel conduit, so I will go that route. It will be easier to work with (slightly), cheaper (a lot), and an inspector will be able to wrap his head around it. He may not understand WHY there is a dedicated line of stranded in pipe across the basement; however he only has to see that it is not a fire waiting to happen. I am not doing anything overly-exotic with the power, just trying to cross my house clean!

Once you get cleared...I would mount the isolation transformer as near the room as possible to keep the secondary feed as short as possible. I would also think about HOW you are going to mount the transformer to reduce hum/buzz from being transmitted into the structure. Mounting on rubber pads or isolators is recommended. and use flexible plastic conduit as well.

Yes, the run to the upstairs outlets will be as short as possible; this was always the plan. However, I had not thought about acoustic isolation of the transformer... That is a good idea. I can do a wooden shelf with a rubber pad with a (some sort of) stone slab on the rubber. New rubber feet (it already has them) on the transformer housing itself is probably a good idea too.

and in the end you haven't done anything to reduce noise or stabilize voltage so i wouldn't go too overboard here.

Really? Not stabilizing the voltage, I fully understand (unless that power transformer has more going on inside than I think it does). But would this not be less noise than running 12-2 Romex across the house bundled with all the other 14-2 Romex feeding the rest of the house and into an outlet in the wall?

And would that not be better than having the stereo outlet daisy-chained with the other convenience outlets in the room? I'm trying to give the system the best shot I can. Sort of like carefully adjusting the speakers you have for the best image, or rebuilding the crossover, rather than replace the speakers all together- working with what you have and controlling what you can control. Am I wasting my time and money?
 
If the outlet boxes are plastic, you don't need isolated ground receptacles. Switching from metal to plastic conduit might be an issue.

It would be good to have the convenience outlets on another circuit. With balanced power it's required.

At work we used Iso-Mode(sp) pads to mount vibrating equipment.
 
The convenience outlets in (that half) of the room are (now) on their own 15A breaker (the other half of the room are similarly on their own 15A breaker). Those original outlets are (were) 1955 wiring practice, so they have metal boxes with the service ground twisted to the backside of the boxes, and no ground wire in the box itself. They also wired through (in on one screw; out through the other) each outlet :rolleyes: which was disallowed some time in the 1970's I think. So, I am going in and putting a pig tail on each outlet and bonding the hot and neutral outside the outlet (rather than in and out of the outlet). It's a PITA, but at least I know it is right, and a failed outlet does not wipe out the chain downstream (which is why this code change came along). I am also installing new outlets as I go, so I know where I have been, and plugged-in stuff doesn't fall out due to weak contacts.;)

After looking through the white paper posted first (http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf), I have made a decision for this installation.

I would like to run rigid conduit (the heavy pipe that is miserable to work with) grounded at the service panel as my service ground, but will more likely be running standard steel conduit (EMT) due to handling ease. Because of that, I may run a ground wire across each pipe junction to ensure a good ground path, but it is probably not necessary. This is why I think rigid is better (threaded on each end for a positive connection).

Within the pipe will be the hot, neutral and Isolated ground lines. I will run that to a metal box (or direct into the transformer enclosure) and then hard-wire to the transformer enclosure, which will use the service ground on its enclosure, but the IG will pass through to the outlet for the stereo.

Output from the transformer will go (as short as possible) to the stereo (20A, hospital) outlet, which will be in a metal box. The BOX will share the ground path of the conduit (the service ground- sort of retro-1955 style), the isolated ground will pass through the transformer enclosure (without contact) to the ground pin of the IG outlet as I mentioned above for a proper IG installation.

The thought process is that the service ground will provide a sort of 'shield' for my power line, while not allowing any induced noise to build up on the equipment ground at point of use (Isolated ground). All ground connections (and neutral) terminate at the same location within the service panel as required, which goes to the ground rod outside as well as the cold water pipe where it enters the house (the pipe happens to be very close to the service panel, and this ground was done when the panel was replaced- water pipe is actually copper too, because of the age of the house!).

One of the two outlets will have a line conditioner plugged in for analogue components; the other outlet will have another line conditioner for digital components. All the power will go through the transformer downstairs, but the point of use will be isolated from one another with power conditioners. (open to suggestions on those conditioners too!) I would like to use 1-rack space (maybe Furman?) conditioners and integrate them into the base of my (home made) equipment rack- maybe a sheet of Mu Metal over them so my power amp (on the bottom shelf of the rack) does not pick up any A/C noise (although that is a Counterpoint SA-220 which has copper plated steel for the enclosure).

The two 110 supply plugs will connect to the two outlets, and at the base of the rack (on the back side) each dedicated conditioner will have the corresponding components and/or their transformers plugged in separating analogue and digital.

I think that will get me as good as I can get without really ridiculous expense (such as balanced power; and I don't think the improvement will surpass the investment, and it seems to only be 'legal' for industrial applications only anyway).

How does that sound?
 
You should use EMT connectors that are compression type not the set-screw type. Grounding and shielding wise I think there are better.
Run bigger wires (#10) that #12 allowed.
Transformer secondary shall have one terminal grounded by NEC. You cannot have "floating" terminals and I won't recomend that either.
 
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I would still advice against the transformer, but hey... it's your choise.

Any transformer on the power path adds up some equivalent series impedance that will degrade the instantaneous current delivery capacity, will "dull" the attack and bass.
I can calculate the voltage drop on the secondary at the maximum load, if you have the data from label of the transformer.
And that is on a continous base, the transients will be much worse.
Only if it is big enough you won't feel that limitation. Something like 50 times the maximum power of your audio setup.
I did advice you for the AC/MC cables VS the EMT because the fact that there are twisted inside the shield and thats why they have lower impedance - good for transients. But you can "skin" some MC cable and use it twisted as it is inside the EMT.
Also probably both the primary and secondary have to be protected the way you are envision this.
 
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I have to remember to get the specs off this thing; maybe a picture as well.

It is definitely big! No question there! Based on its original purpose, I always assumed those sort of things had been addressed; but I will open it up and see what's 'under the hood' on this beast...

If it is a simple 1:1 tranny, it probably is not worth using it sounds like. Since it was designed for the purpose of 'cleaning' the power for a large old computer, I assumed it would be adequate for a stereo rig... (I think it is 'Data General' branded but could be wrong- going from memory here!):confused:
 
If there`s one thing I`ve learned; remove all stranded wires, signal or power. You can do a simple test to get a clue by running one stranded and one massive powercable, lets say 20ft long.

No cleaning-trafos survives in my system, even if I get them custom made like all my trafos. Everything that ears dynamics are banned, first of all multicore wires.
 
OK.

I built a passive preamp years ago from the Stereophile design and that was all solid cored wire when I built it. Unfortunately, I overheated the buffers installing them, and it has sat unfinished for years...:mad:

At that time, I believed solid was the way to go for signal; power was not such a hot topic as it seems to be these days.

Solid 12ga copper power leads to each component sounds particularly unpleasant to try and work with! Is this what you use?
 
don't think think was mentioned yet...why not run a dedicated 240 volt "dryer" circuit with standard large 3-prong receptacle. Can your power conditioner be configured for 240?, plus you have all sorts of high current wiring options after it passes inspection. Maybe you can have the line run with flexible metal clad wiring-I forget the brand name at the moment. That style is used in garages and such for added protection. Get the large conductor size with 4 wires, so one is a ground and also ground the metal clad jacket. And I believe all of that may be a more or less a standard dryer run.
 
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