Dedicated power circuits

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).

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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.