Dedicated power circuits

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.

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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.