15A vs. 20A power cord questions

asp307 said:
It was recommended to me by a US producer of speakers/cables to ground to the earth using rods and to use a twisted pair for the connection between the breaker and the outlet.

Send him a copy of this.

Quote from Link below:

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"Grounding Myths

From Henry W. Ott’s big new book "Electromagnetic Compatibility Engineering"

3.1.7 Grounding Myths

More myths exist relating to the field of grounding than any other area of electrical engineering. The more common of these are as follows:

1. The earth is a low-impedance path for ground current. False, the impedance of the earth is orders of magnitude greater than the impedance of a copper conductor.

2. The earth is an equipotential. False, this is clearly not true by the result of (1 above).

3. The impedance of a conductor is determined by its resistance. False, what happened to the concept of inductive reactance?

4. To operate with low noise, a circuit or system must be connected to an earth ground. False, because airplanes, satellites, cars and battery powered laptop computers all operate fine without a ground connection. As a mater of fact, an earth ground is more likely to be the cause of noise problem. More electronic system noise problems are resolved by removing (or isolating) a circuit from earth ground that by connecting it to earth ground.

5. To reduce noise, an electronic system should be connected to a separate “quiet ground” by using a separate, isolated ground rod. False, in addition to being untrue, this approach is dangerous and violates the requirements of the NEC (electrical code/rules).

6. An earth ground is unidirectional, with current only flowing into the ground. False, because current must flow in loops, any current that flows into the ground must also flow out of the ground somewhere else.

7. An isolated AC power receptacle is not grounded. False, the term “isolated” refers only to the method by which a receptacle is grounded, not if it is grounded.

8. A system designer can name ground conductors by the type of the current that they should carry (i.e., signal, power, lightning, digital, analog, quiet, noisy, etc.), and the electrons will comply and only flow in the appropriately designated conductors. Obviously false."

Henry W. Ott

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Posted by Speedskater:
Dedicated Power Line Recommendations - REPRISE! »

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asp307 said:
Regarding a twisted pair or standard cable to link the breaker to the outlet, any advantages or is it all about the grounding?

About how long will the branch circuit run be? Don’t forget to figure up, down, and around, when figuring the total length of the run. (2 conductor with ground only! Hot, Neutral, and ground)

The wiring and wiring method used depends on the state and or local electrical code of Pittsburgh, PA. The electrician you hire will know what is code for your town. He will determine what will work for your wiring installation job.

IF NM-B sheathed cable, (Romex is a trade name of), can be used for the electrical wiring installation that works great for audio dedicated branch circuits.

IF because of code or because other reasons it has to be in conduit ask the electrician if MC aluminum armor cable meets code for your town. (2 wire with ground only! Hot, Neutral, and insulated green wire.)

If that meets code make sure he buys solid wire conductors and not stranded wire. Don’t let him talk you out of it. Especially if you want to use #10awg wire. Trust me he will try to get you to use strand wire. If he says nobody has 10-2 with ground solid wire MC AL armor cable tell him to try an electrical wholesale house in town. They will have it.

Worse wiring method for audio branch circuits is for the dedicated branch circuit wires pulled in an empty conduit where they are loose and randomly laying inside the conduit. This method can lead to induced voltage noise on the equipment grounding conductor.

A true dedicated branch circuit does not share a conduit or cable with any other branch circuits.

Example: 10-2 with ground NM-B sheathed cable.
http://www.wireandcabletogo.com/10-2-W-G-NM-B-Wire-Orange-250ft-500ft-or-1000ft-Coil.html?gclid=CP3y...

Example: MC AL armor cable
http://www.southwire.com/products/ARMORLITETypeMCOEM.htm

asp307 said:
"I’m installing dedicated 20A lines with 10AWG cable"

Lines? More than one.

Not knowing what the wiring layout method will be for the NM-B cable installation, if possible after the electrician gets out of the electrical panel and starts the horizontal parallel runs of the cables ask him if possible to keep them separated from one another by at least 12". If they are installed right next to one another for several feet when a connected load is connected to the cables the current carrying hot and neutral conductors magnetic fields will induced AC voltage/noise onto one another. (Same reason why dedicated branch circuits should never be installed in a conduit or raceway with other branch circuit wiring.)

Have him keep the dedicated branch circuit NM-B cables away from any other branch circuits that may have light dimmers connected to them. The load side wiring as well as the line side feeding the dimmer, (when turned on light/s dimmed), emits Harmonics RFI as far as 3’ to 5’ in all directions from the wiring. (The wiring becomes an antenna). If your new dedicated circuits are closer than 3’ the wires will pick up the RFI from the dimmer emitting wiring.
https://www.youtube.com/watch?v=OCK5W9vlAE0

When he connects the branch circuits to the branch circuit breakers in the electrical panel make sure they are all fed from the same Line,leg. All from Line 1 or all from Line 2. Not from both.

Have him verify they are all connected to the same by using his volt meter and measure for voltage from the Hot contact of one duplex receptacle dedicated branch circuit to the Hot contact of all other dedicated circuits duplex receptacles.

If they are all fed from the same Line, leg, he will measure zero volts. If he measures 240Vac nominal between any of then they are fed from both Lines.

For audio equipment connected together by wire ICs you want all the equipment fed from the same Line, leg.

I installed two dedicated circuits using #10-2 with ground MN-B cable.

One for digital and the other for analog.

It’s you call if you want to spend the extra money for the other line.

Because you are using #10 branch circuit wiring you should not have any fluctuating VD, voltage drop, problems playing moderate to loud dynamic music through your amp. And because all your equipment is analog one dedicated circuit is probably all you will ever need.

If you think there is a chance some time down the road you may add some digital equipment to the mix you could have the electrician install another cable now for future to a separate cut in wall box. Just have him put a blank cover plate on it for now. At the electrical panel he could terminate the neutral and equipment ground wires and tape off the end of the black hot wire for the future if you decided to use it. Extra price? Material plus just a little more labor cost. Definitely cheaper now than later. Future hook up cost? One hour labor rate, should cover it.