Power Newbie: Electrician Coming

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jea48

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Re: Power Newbie: Electrician Coming
« Reply #40 on: 5 Nov 2013, 01:13 am »
Thanks Phil.  How would one utilize two receptacles on two circuits?

Any specific instructions I should give the electrician?  Any thing I might want to consider for the outlet?

headshrinker2,

If you mean a duplex receptacle, (2 receptacles supported by one yoke, back strap), per NEC code the two circuits shall be fed from a 2 pole breaker. For safety both circuits must be de energized by a one handle operation for maintenance.

Problem with using a 2 pole breaker each circuit would be fed from both Lines, legs, from the electrical panel. As is common practice equipment that is connected together by ICs should be fed from the same Line, leg, of the electrical panel.
« Last Edit: 5 Nov 2013, 02:56 am by jea48 »

jea48

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Re: Power Newbie: Electrician Coming
« Reply #41 on: 5 Nov 2013, 01:43 am »
Ummmm, that 2nd circuit will greatly increase the likelyhood of ground loop hum and noise. If those outlets with individual circuits are a couple of feet from your panel, its probably not a problem.  Each separate circuit from your panel will have, by Code, its own safety ground wire running back to the panel. If distant from the panel, you are, by definition, increasing the ground loop length and the associated voltage drop and current flow on the ground.

FWIW, YMMV,
Paul

For my 2 channel system I have 2 dedicated branch circuits that are over 75' long each. The wire is #10-2 with ground NM-B slightly twisted the entire length. Runs are separated by at least 1' from one another until within about 15' from the electrical panel. Both runs are one piece each, no splices.
The wire is connected to 2 square D OQ 20 amp breakers installed directly across from one another.  (Both connected to the same main bus breaker connecting tie)

All digital is plugged into one dedicated circuit, analog the other.
Duplex recepts are Old style Hubbell HBL8300H non plated cryoed treated.

Preamp is a Sonic Frontiers Line One (tube). Amp is a ARC VT 50 (tube). The system is dead quiet. Yes tubes, dead quiet.
 I have never had a ground loop hum.
« Last Edit: 5 Nov 2013, 04:21 am by jea48 »

jea48

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Re: Power Newbie: Electrician Coming
« Reply #42 on: 5 Nov 2013, 02:55 am »
Hello,

I don't know but i put in the isolated lines and i did not connect the ground to the electrically panel but a separate grounding rod that was grounded into the earth. I believe that is within code and never had any ground loop problems at all unless you introduce something that was not on the same ground. Also in my experience doing this project was well worth it and any my system never sounded better.

So i think it goes to show that not every one has the same experience and you just have to make up your own mind based on the info that is out there.

Once again, Good Luck

I don't know but i put in the isolated lines and i did not connect the ground to the electrically panel but a separate grounding rod that was grounded into the earth.

In the event of a dead short ground fault it works great for hunting fish worms. Just keep pets and bare footed humans out of the area of the ground rod on a heavy dew morning.

Mother Earth does not possess some magical mystical power that sucks nasty’s from the AC mains of our home.

Per NEC code. The earth shall not be considered as an effective ground fault current path.

In the case your isolated dedicated ground rod is called upon to pass a ground fault from a piece of your equipment, or a shorted hot to ground power cord connector, or whatever, if a path is provided the fault current will take any path available to return to the source. It likes the least resistive path but it is non-discriminating, it will take any path available.

Possible paths?
If the rod is close to a driven rod for your main electrical service it will head there. It will enter that rod and travel to the grounded main service neutral in the electrical panel.
Of course if the moisture in the earth is low, soil resistance could be high and not enough current will flow to trip the branch circuit breaker open feeding the ground fault.

Your neighbor’s house. If your neighbor happens to have his electrical service on the same side as your isolated ground rod the current will go through the earth enter his rod go to his electrical panel to his main service neutral then go outside on the service neutral and head for the power transformer that feeds your house.  And again if the ground fault is a dead short will the earth resistance prevent enough current flow to trip the breaker open in the electrical panel in your house?

The Utility power transformer. Usually power companies connect the center tap of the secondary side to a wire that is connected to earth. This could also be the path for the ground fault current to flow through the earth to get back to the source.

It will take any and all paths available.

 http://www.aes.org/sections/pnw/pnwrecaps/2005/whitlock/whitlock_pnw05.pdf

Also the dedicated isolated ground rod has a better chance of frying your audio equipment from a lighting strike. Lightning can travel horizontally through the earth for, I believe, up to 5 miles. 
« Last Edit: 5 Nov 2013, 04:12 am by jea48 »

Speedskater

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Re: Power Newbie: Electrician Coming
« Reply #43 on: 5 Nov 2013, 02:20 pm »
I must say that 'jea48' has an excellent understanding of AC power and how it interacts with audio systems.

One very small point: Ralph Morrison suggests bundling all the AC power cords that go from area A to area B. He also suggests bundling (in a different bundle) all the analog interconnects that go from area A to area B.

And to repeat an important point:  All the ground rods must only connect to the building electrical system near the service entrance.

jea48

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Re: Power Newbie: Electrician Coming
« Reply #44 on: 5 Nov 2013, 04:46 pm »
One very small point: Ralph Morrison suggests bundling all the AC power cords that go from area A to area B. He also suggests bundling (in a different bundle) all the analog interconnects that go from area A to area B.
Speedskater


Power cords are not the same as building branch circuit wiring.

When branch circuits are bundled together for long runs voltage will be induced across conductors of other circuits of other branch circuits. How about EMI/RFI and harmonics?

In the commercial/industrial electrical industry as a rule a true dedicated branch circuit that is used to feed electronic equipment does not share the same conduit, cable, or raceway with other branch circuits.

Been awhile since I have read any white papers of Ralph Morrison.  Could you please post the link of the white paper or book you refer to along with the year Mr. Morrison wrote it.
Were SMPS, switch mode power supplies, around then? How about digital equipment? Harmonics like we have today?

I do not bundle the AC power cords of my audio equipment.  Nor the ICs.
 Who does that today?
Jim