AC Power Cord Wire Gauge


I guess this is a two-fold question dealing with the amount of AC power flowing through normal - that is, not special 20 amp dedicated lines - 15 amp house circuits. I'm guessing that these lines use 14 gauge wire, with a 15 amp breaker, to say a duplex receptacle. One conversion I read is that 15 amps X 120 = 1,800 watts. 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 (i.e., the power isn't split between the two outlets in the receptacle)? If you plug another component into the other outlet does it reduce the power available to the "power strip"?

Second, if the house wiring to the duplex receptacle is 14 gauge from the electrical panel, does it make any difference if you buy heavier (say a 10 gauge) after-market audiophile power cords for the audio components? Or, would a 14 gauge cord - the same gauge as the house wiring - be sufficient? Can a 10 gauge cord flow more power than is available through the house wiring at 14 gauge?

Thanks.
kencalgary

Showing 7 responses by almarg

Some very smart individuals with electrical engineering backgrounds will make compelling arguments in favor of using the same gauge wire in power cords as that which is in your walls because from an engineering standpoint it makes sense to do so. It will be very difficult if not impossible to fault their position.

Tvad -- I have an electrical engineering background, and some people consider me to be very smart :), but I for one do not make that argument, and do not see why "from an engineering standpoint it makes sense to do so."

Best,
-- Al
Re question 1: Assuming the house was wired properly, the only constraint for what is connected to a 15 amp branch served by a 15 amp breaker is that the total current drawn by all devices that are plugged into all outlets on that branch, and all devices such as overhead light fixtures that may be wired to that branch directly, should be less than 15 amps. So, yes, if you plug additional components into the other outlet the power that would be available to the strip would be reduced correspondingly.

Re question 2: The current drawn through the component power cord is determined by the internal design of that component, with minor variation depending on the exact line voltage. As long as the house wiring and the power cord are of sufficient gauge to conduct that amount of current, meaning that they have low enough resistance to prevent significant voltage drop in the wiring and power cord themselves, there will be no difference in the power supplied to the component either way. If some listeners are able to perceive a slight sonic difference between the two cords, it will not be because of the difference in gauge (provided, as I say, that the gauges of both the house wiring and the power cord are adequate for the current draw of the component(s)).

Regards,
-- Al
You can see by the statement you quoted that I am not scientific enough to posit an intelligent response ...

On the contrary, I sincerely felt that your entire response was quite intelligent. In that particular part of it, you were simply citing what you believe some others believe, and I have no doubt that is true (that some others have that belief). I was just saying that that belief that others may have is, in my opinion, not correct!

All the best,
-- Al
The age-old question, "Why make PC's any bigger gauge than what's in the wall?" has a very simple answer: 'energy transfer' I'll explain:
When you plug your whatever into a wall receptacle, you are basically hooking it up (in parallel with other devices plugged into that same 'branch' circuit) across two buss wires (hot and neutral) coming from the panel. Think of this buss (usually a long length of Rom-ex in the wall) as a reservoir of water that under most conditions can never be emptied. Think of the power cord as a pair of tubes (hot conductor and neutral conductor) that you stick into this reservoir. Now water can flow (current) into one conductor, through the whatever, and back out the other conductor (and this process reverses 60 times a second because the current alternates.)

If the water is flowing through an amplifier, it's doing quite a bit of work, but in just a sixtieth of a second, it has to get back to the reservoir and then reverse direction! Sounds like an electron traffic jam waiting to turn into gridlock! To insure this doesn't occur, you provide many many lanes (or in this case, large conductors) and you lay them out so drivers aren't blinded by oncoming headlights (inductance and capacitance) slowing things down unnecessarily ;-) Simply put, the energy transfer requirements, back and forth between the device and the reservoir, are quite different in nature than what it takes to keep the reservoir full.

At the risk of starting an ecclesiastical controversy (which I hope will not occur), I must respectfully but completely disagree, because as an electrical engineer I believe the quoted perspective would be severely misleading to the original poster and to others who may read this.

Simply put, there is no basis whatsoever in science or engineering for viewing the ac outlet as a point of demarcation between a reservoir, and a set of tubes or whatever that draws water (or in this case current and power) from the reservoir.

The wiring system is just that, a system. Energy is being transferred back and forth at a 60Hz frequency through the house wiring just as much as through the power cord. Increased resistance in the house wiring, due to smaller gauge or greater length, will produce a voltage loss just as readily as in the power cord. And in fact most likely to an even greater degree (since the combined current draws of multiple devices are likely to be flowing through it, rather than the current draw of just one device, and voltage drop equals current times resistance).

As I said earlier, there may be subtle reasons why subtle sonic differences may result when 10 gauge power cords are hooked into 12 gauge house wiring, but the differences are not due to the gauge per se.

Regards,
-- Al
Nsgarch,

I take no position on your findings that "the effect of using larger (and larger!) gauge conductors is the same, regardless of the brand or topology of the cord." I have no reason to doubt that your sonic perceptions were accurate, although I'm sure that there are many others whose listening experiences and perceptions would both support and contradict your conclusions.

I would certainly keep open the possibility that there are as yet unidentified design characteristics among audiophile-oriented power cords that tend to correlate with gauge, that might SEEM to produce a correlation between gauge and performance.

Obviously science and engineering certainly cannot, at this point, explain everything about why we hear (or think we hear) what we hear. But they can explain a lot of things. And my basic point, I guess, is that having no explanation is far preferable to having an incorrect one. Because the incorrect perspective that can result from an incorrect explanation can negate the value that good science and engineering CAN bring to the table.

Best for the holidays and new year!

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

While everything in the quote from Shunyata sounds correct to me, it's dealing with effects at rf frequencies, which I don't think would be a function of gauge per se (at least among the gauges we have been discussing).

Regards,
-- Al