Does an isolation transformer improve a power cable?

Yes, I have a dedicated 240 volt line, made from 10 AWG Romex and a 30 amp breaker.
01-01-15: Jafreeman

The 30 amp breaker does nothing more for the available power the ISO xfmr can draw from the main electrical panel than the correct size 20 amp breaker would. The total power that the ISO xfmr can deliver to the connected load is limited by the circuit breaker mounted in the front of the ISO xfmr unit. That breaker is there to protect the unit from a continuous overload or short circuit.
The current carrying contacts inside a 30 amp breaker are exactly the same size as a 20 amp breaker. The only difference is the thermal and magnetic trip unit settings.
The #10 wire was a good idea but it should be connected to a 2 pole 20 amp breaker.

There is a reason why the manufacture of the ISO xfmr specs a 20 amp circuit, there in a 20 amp breaker. He is following NEC Code which says a 20 amp rated receptacle can only be connected to a 20 amp breaker.

No need to lift the ground--the house ground is not involved,

I hope that does not mean a separate earth ground, ground rod, that is not connected to the main grounding system of the electrical service of your home.

There is a reason why NEC Code requires the neutral conductor of a separately derived power system, (there in the neutral conductor of the secondary winding of an ISO xfmr), to be connected to the main grounding electrode system of the main electrical service. It can be connected to it at any point. (Technically a safety equipment grounding conductor is not part of the grounding electrode system, though it connects to it.)

If you do have a dedicated earth ground that is totally separate from the main grounding system of your home I hope you did not break the equipment grounding conductor/connection that connects to the ISO xfmr unit from the 240V branch circuit that feeds the unit. That could be dangerous.

The Earth does not possess some magical mystical power that sucks nasties from an audio system.
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Jim, thanks for that clarification. I should have said that the ampacity I ran ends at my receptacle. Beyond that, the product supplies a 12 AWG cord and a 20 amp breaker. The cord is grounded to my receptacle and into the transformer. The company claims of protections from surges, elimination of ground loops--at least between gear in the system-- instantaneous power on demand have led me to believe this is an isolated power supply. At any rate, the results say just that--there is no noise, there is no loss of voltage, no clipping, a vastly improved soundscape--lots of "headroom". I have not altered the unit in any way--it is plug-and-play--just need the outlet. They are expensive-got mine for half cost here on 'Gon from an installer who had an extra--otherwise, would have tried Torus Power, also very costly, but well regarded.
I just wanted to report my findings using OCC copper in my DIY AC cables that are supplied by this clean power---outstanding!

mmmm, this thread is informative, jea48, please call me, if you recieved my #, I have done what you have specified, LOL!, everything in my house affects the sound of my sysytem, I have dedicated lines, I need dedicated breaker box with it's own ground for the system!, the ground is where this problem is, there is no other answer?

I wonder if anyone has converted 3 phase to a home use 120 line like this. I suppose that would even give better quality AC.

Just to be a bit of naysayer/ clarifier the transformer does not "create" electricity as I have stated before. It is just isolating you from the grid from "quick" spikes and drops, any long term spike or drop will effect the other side of the transformer.

The best way for clean AC is to have your own method of developing the AC signal from either using the grid power to DC and then back to AC or from off the grid sources as in solar and wind. The last two are becoming quite popular and should be able to create amazingly clean power (based on the inverter)

Just to be a bit of naysayer/ clarifier the transformer does not "create" electricity as I have stated before.
01-02-15: Scvan

Scvan,

Other than you, who has made such a statement?

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Separately Derived System.

NEC 2011
Article 100
Definitions

Separately Derived System.

A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct connection from circuit conductors of one system to circuit conductors of another system, other than connections through the earth, metal enclosures, metallic raceways, or equipment grounding conductors.

>>>>>>>>>>>>>>>

The revised definition in the 2011 NEC defines Separately Derived System as: A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct connection from circuit conductors of one system to circuit conductors of another system, other than connections through the earth, metal enclosures, metallic raceways, or equipment grounding conductors.

http://www.jade1.com/jadecc/courses/UNIVERSAL/NEC05.php?imDif=10

http://www.jade1.com/jadecc/courses/UNIVERSAL/NEC05.php?imDif=10

>>>>>>>>>>>>>>

A separately derived system is a premises wiring system with no direct electrical connection to conductors originating from another system [Art. 100 definition and 250.20(D)]. All transformers, except autotransformers, are separately derived because the primary circuit conductors do not have any direct electrical connection to the secondary circuit conductors. Generators that supply a transfer switch that opens the grounded neutral conductor would be considered separately derived [250.20(D) FPN 1].

http://ecmweb.com/nec/grounding-and-bonding-separately-derived-ac-systems

An Isolation transformers is a Separately Derived System.

>>>>>>>>>>>>>>>>

Separately Derived System. A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system.

.
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Some examples of separately derived systems would include:
•Transformers, shown in photo 1, where the supply side is isolated from the derived side except by magnetic coupling
•Generators (motor, wind, or engine driven), one example shown in photo 2 and figure 1, where it is either a totally stand-alone system or is an alternate source of power and the grounded conductor (neutral) is not solidly connected in the transfer switch or transfer equipment
•Battery/inverter systems where the output is not interconnected
•Photovoltaic systems where there is no interconnection to the grid or another energy source (off grid system)

Some examples of separately derived systems would include:
•Transformers, shown in photo 1, where the supply side is isolated from the derived side except by magnetic coupling

http://iaeimagazine.org/magazine/2009/11/16/separately-derived-systems/

http://iaeimagazine.org/magazine/2009/11/16/separately-derived-systems/

*********************

The main benefit offered by Isolation Transformers is
the input-to-output isolation, where the output circuit
can be re-grounded and isolated from input or other
ground noise sources. This isolation can also be useful
where Ground Potential Rise protection can not be
afforded by normal bonding procedures.

http://www.erico.com/public/library/fep/technotes/tncr016.pdf
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