Dedicated power circuits

@ditusa 

Thanks for the detailed explanation. I'm using two identical runs from 20A breakers, one for analogue and one digital. Tube amp plugged into wall. Audio system is only 20' from panel so I used 12/2 Romex. No ground loop, no RFI (tested with a meter).

ditusa,

Your installation is almost identical with mine. I'm running 10/3 MC 240v. A 20 amp circuit dedicated to each mono block, 20 amp circuit for pre amp, and a 20 amp circuit for digital. All galvanized gang boxes. 

I desigbed and build that all in one AudioUltra panel.  I have modified it since inception.  It can't be beat when installed  in the right application.  That application is on a wall between monoblock amps and subs.  I don't use a power cord.  Its bolted directly to a feeder wire and capable of passing 225 amps. 

An all in one Torus distribution is great, but not so great.  Its a better suited product in recording studios where many have been installed.  There are much better ways to integrate a Torus in a residence. 

I had to have the second phase run at Fremers because I could not get a letter from SqD  saying a Square D subpanrl rated 120/240 was suitable for 120 only.  In response to this, I manufacture a 225A all copper panel with a UL label rated for 120 volt only.   Yes you only use one phase. 

I went back to Fremers and changed out that panel in the image above. .  I now rework those SqD QO MLO 125 to 200A subpanels with damping compounds and install all copper neutrals and grounds.  Its a shockingly good panel for the money when rebuilt.  Stock they are little better than a couple others.  There is crap ou there like Homeline and Eaton/Siemens/CH BR style.  Waste of money.  And they limit performance.  

The primary feed from the utility to the receptacle in the wall can be very sensitive to how the wiring is installed.  The best electrician out there is going to do it wrong  because he does not have experience powering something as sensitive as an electron microscope.  Thats your stereo.  He will do what all electricians do, meet code minimum.  Anything more in their mind is a waste of money.  They don't get it.  That twisted wire at Fremers.  I grain orient it.  Tell an electrician that and their eyes glaze over.  Tell that to a cable manufacturer and they will acknowledge you know one of their secrets.   When wire is drawn through dies to size it, it gets a grain.  I have heard it called a Chevron.  Its audible and measurable.  I am the only person in the US I know of who is talking UL THHN/THWN solid 10 awg and determining its grain, then orienting all 3 hot, neutral and ground before installation.  Others have stuck wires in a drill and twisted them.  My tools are more clean and precise.  I built a custom bobbin and twist the wire 1 turn every 2 inch.    I am soon going to Cryogenic immersion bath this wire. 

I don't like MC cable or wire in a steel pipe.  I use it when I have to such as in NYNY.  Otherwise its a can of worms.  It creates ground loop issues.  It really blocks no RF.  Its there to stop fires as an arch in the conductors rarely propagate ouside the metal case.  Steel will block a small amount of emf from one branch circuit to another.  But the steel case is interacting with the electro magnetic field around the wire and compressing it. In my mind Its not ideal.   But I do need to test it more.

I do not like 8 awg and larger.  MSB may have written a paper saying you want to upsize to larger gauges for longer runs, but every wire is audible.  8 is analytical.   It grabs your attention and makes you aware of different parts and pieces in the music.  Its harder to relax and enjoy.  10 is plenty of current.  Romex is decent wire.  If your on a budget, use it.  Its a little hard and slightly analytical,  but not like 8.  Romex is great for subs.  8 can be too.  They speed up the bass.  Grain oriented twisted is more whole and complete in tone.  Its easier to digest the whole of the presentstion and relax while listening.  Its a little fuller, but looses no resolution. 

The all copper panels I mentioned are nice as you eliminate the galvanic reaction between the copper and aluminum.   Its audible.  Its heard as a sleigh  veil and haze.  A small amount of lost resolution and softening of the music.  If you have SET amps and horns, you might find it tames some of their potential "Hot" dynamics.  It could be consodered a tone control.  I prefer to rid noise and work on taming the speaker/room issues in the room.  Not in the electrical infrastructure.   

Rex

I had to have the second phase run at Fremers because I could not get a letter from SqD saying a Square D subpanrl rated 120/240 was suitable for 120 only.

That jogged my memory. Sounds like the Electrical Inspector was using NEC 110.3 (B). Square D manufactured the Load Center to be connected to a split phase 120/240V AC source. The ampacity rating of the neutral bar can be, is, sized smaller for a split phase AC source because as you know the service neutral only carries the unbalanced load back to the neutral of the secondary winding of the power transformer. The neutral bar ampacity rating would not be rated big enough if the panel was connected to a 120V only source. (IF the panel was loaded to its full rated capacity.) There is the problem.

After reading your post I remembered having a conversation with my friend in Texas when I suggested feeding the electrical panel for his audio room equipment 120V only. In my friend’s case the panel was fed from a 15KVA isolation transformer. (Primary 240V, secondary configured for 120V only). I remembered talking to him about the electrical panel and the possible problem with the electrical inspector approving it connected to 120V only. I told him the ampacity rating of the neutral bar would be the possible problem. It depends on how well the inspector is versed on the NEC... He said, can’t I have my electrician just change out the neutral bar? No... Doing so will void the UL Listing. The Electrical Inspector, if his knows the NEC, as well as the electrical panel, will spot the neutral bar was changed out and flag the panel, If the panel was modified it needed to be re-Listed for the modification. No Listing, it can’t be installed. (NEC 110.3 (B) (C) ).

As for the panel for the audio room my friend wanted the best. Money was no object... Imo, a Square D panelboard with QOB bolt on breakers.

His isolation transformer would be 15KVA. At 120V the xfmr was good for 125A. I suggested he over size the ampacity rating of the panel. I can’t remember what I recommended. I do remember the Electrical Inspector passed it being fed 120V only but required the Electrician pull/install a spare conductor the same size as the existing ungrounded conductor for future, possibility of, feeding the panel 120/240V.

/ / / /

As for Fremer’s video, he made the day of rewiring of the electrical service for his home, I cringed every time Fremer would say "every thing according to code". He said it several times in the video. I was surprised you guys didn’t suggest he stop saying that... As you know Code is bare minimum electrical safety standards... NEC could care less how an audio system sounds. All NEC cares is if it is electrically safe...

Jim

Don't we need metal boxes at each wall outlet and each metal box gets its own ground wire ran back to the panel? These grounds are separate from the romex.