AC Power Cord Wire Gauge

Nsgarch, the biggest Fairy Tale in contemporary society is the belief in spontaneous generation of life apart from a causative agent. :)

One conversion I read is that 15 amps X 120 = 1,800 watts.

True in simple terms but there are other factors that come into play. Depending on the type and load placed on the branch circuit can effect the total amount of power, watts/VA that may be available. Just one example would be the voltage drop on the branch circuit caused by the amount of load placed on it.

Using your your formula amps X volts if the voltage drop on the branch circuit was say 5 volts then the total available power, watts, would be 15 amps X 115 volts = 1725 watts. Again in simple terms.

So, the first question is: If you plug a surge protector/power strip/power conditioner into one outlet in the duplex receptacle and then plug, say, four audio components into that "power strip" can they draw the full complement of AC power available..........?

Yes, provided no other loads are connected to the same branch circuit.

If you plug another component into the other outlet does it reduce the power available to the "power strip"?

The branch circuit ampacity rating is determined by the overcurrent device, breaker in this case, feeding the branch circuit. If the breaker is working properly when a continuous load reaches the breaker handle rating the breaker should trip open. Key word should.

Depending on the branch circuit wire size, # 14awg is the minimum size for a 15 amp branch circuit, and the total length of the branch circuit wire plus the total connected load will determine the voltage drop on the line.
In other words if the branch circuit length is long, as a continuous load of say 15 amps is approached the voltage drop could be sufficient to effect the sonics of your audio system....
Again in simple terms.

Some food for thought, in the case of a power amp, the load placed on the AC line can be fluctuating depending on the dynamic demand that is being placed on the amp. You could very well have spikes well above the 15 amp rating of the branch circuit breaker.

Simple terms? Throw in inductance, capacitance, harmonics, and what ever else that may be thrown into the mix and the whole thing changes.
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Check out what this EE has to say about power cords.
Some of Jon's explanations can also be extended to the size of the conductor, wire, used for a branch circuit run when it comes to voltage drop on the line due to the load placed upon it by the power supply/s of audio equipment.

Check out what this EE has to say about power cords.

Interesting writeup, Jea. Thanks for calling it to our attention.

Pretty much all of it rings true to me. And I think that he really manages to get across the notion that the perspectives most of us (both EE's and non-EE's) tend to bring to these issues are overly simplistic. And he provides some good insight into why stock power cords can be usually, or at least often, be expected to underperform.

He does not, by the way, address in any explicit way the issue of the benefits or lack thereof of using a power cord that is heavier gauge than the wiring inside the walls.

Putting aside his extensive technical verbiage, I would summarize his main points as follows:

Most house wiring is either 12 gauge or 14 gauge, while many OEM cords are 18 or at best, 16 gauge. Most OEM cords do not have shielding or any provision for reducing radiated EM fields, do not have premium AC outlet plugs or premium IEC plugs for better electrical contact at these junctions....

As always, the bottom line is: you have to listen for yourself, and see if their is any benefit for you, on your system, with your listening habits....

Some of the cord/cable manufacturers get carried away with using only the very finest materials and assembly techniques, carrying over the technology and costs from their high end audio interconnects and speaker cables. Is this necessary? I don't know, I will not discount it out of hand. Does it make the cords cost a lot? Yes.

Regards,
-- Al

Al,
Risch's post on AA was from Nov 2000. Lot has been learned since then regarding the effects a power cord can have on a piece of audio equipment.



This may have something to do with the larger conductor size in PCs. Don't know for sure though.

Question: There is a tremendous amount of electrical interference and EMI coming from outside the home that we need to protect our equipment from. This implies that we need some sort of power conditioner or filter to protect the equipment.
Answer: Most of the EMI that affects the audio quality of a system is generated by the audio components themselves. EM waves that travel through space dissipate in power as the square of the distance from the source and very high frequencies that propagate through the power circuit do not survive for long. Power lines present a high impedance to Mhz and Ghz signals due to the relatively high inductance of power lines.

A primary source of audible sonic degradation is caused by the power supplies. Most components use FWBR (full wave bridge rectifier) power supplies that generate an incredible amount of transient noise when the rectifiers switch on and off. The design of a power cord can significantly affect the reactance of these signals within the power supply. Because the power cord is part of the primary winding of the power transformer, the transition between the various metals used in a PC can cause EM reflections and diode-like rectification of the noise impulses as they propagate away from the power supply. If the PC presents a high impedance to these signals they will be reflected back into the power supply where they will intermodulate increasing the high frequency noise levels of the component. Most power supply filters are ineffective at blocking very high frequency noise components and much of it is passed through to the DC rails. The sonic effects of this include: high background noise levels, blurred or slurred transients and a general lack of clarity and purity of the sound or visual image.

Quote taken from shunyata info
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Thanks Jea for adding some valuable information to my (limited) knowledge of powering my equipment. I also appreciate the reference to Jon Risch's info which is also very useful to me. Hope you all have a Happy New Year. Many thanks.