Power cord 15amp and 20amp

Jim, yes, and yes. I totally agree with you about the desireability of floating the shield at the component end. A friend of mine, very knowledgable (formerly of Wadia) instructed me on interrupting the shield at the IEC end of an OEM PC to make it a floating shield. Away went all the digital RFI being broadcast from my DAC!

I agree with what you said in your second paragraph, but I've not seen any cords made that way (yet!)

Your last comment, I'm not sure about. It used to be true, but today, if you have 3-conductor hardware on each end of your PC, I think UL insists on a ground connection on each end (I'm not 100% sure on this one.)

Neil, if the PC also has an equipment grounding conductor does UL still require the shield to be grounded on both ends? It would fly in the face of the way a shield works would it not. I was always taught to ground the shield at one end only and that being the end closest to the direction of earth ground, in this case the NEMA male plug.

If on the other hand a manufacture did not also include a separate equipment grounding conductor in the cord and only relied on the shield for the equipment grounding conductor then I could see where the manufacture would have to connect the shield also at the IEC connector end of the PC.

The manufacture of equipment can control whether they want to use the equipment grounding conductor of a power cord.
My Arcam Alpha 9 CDP has an IEC male connector and the connector does not have the equipment ground blade. The CDP does have a metal case, a Farady cage. They must build it insulated such that there is no chance of the case coming into contact with any power conductors.

Hi Jim,

You are quite right regarding the UL certification. And I was referring to the fact that not all vendors are entirely candid in their descriptions (which is why I said, " just so you won't be confused/misled")

And while we're on the subject of UL certification, I recently found out that UL specifies that if a PC has a shield, that to be UL certified, the shield must be connected to ground at both ends -- which in all OEM cords they are (so the manufacturer of the amp, or whatever can get a UL rating on the equipment itself.)

Since (IMO anyway,) floating shields are preferable, I suddenly realized why a lot of aftermarket cords might sound a little better even though they're not that different in materials or construction than the OEM cord they replaced (and also why they're not UL rated, I guess.)

>>"Quite often, cords are described as "20 amp" cords even though they have 15 amp hardware (plugs). This is because the wire conductors themselves are 20 amp capacity. The only reason I can think that cords are sometimes described this way is to indicate that they are capable of powering high loads (like big amplifiers.)"<<
[Nsgarch]
>>>>>>>>>>>>>

Neil, although a manufacture might say his cord is rated at 20 amp because it uses #12 awg wire, the Nema 5-15P plug and the 15 amp IEC receptacle, UL dictates the rating shall be 15 amp. Because of the connectors the max continuous load would be 12 amps. A power cord with 20 amp connectors max continuous connected load of 16 amps.
=========

>>> "It's all about energy transfer."<<< --
[Jim Aud, Purist Audio Design]

That says it all, even though a power cord may be rated at 15 amp with #12, or larger, awg wire it is capable of handling quick fluctuating peaks of current with out any sag in voltage.
Jim

Nsgarch (Neil)

WOW Neil. Thank you for taking the time to explain this in very simple terms. The analogy makes it very clear now.

Thanks

here i go

yes it's about the energy transfer. The vibration of the energy and not a fixed number or the absolute entity (electricity)

i can pluck any instrument with anything. Plastic pic ,my fingers , a bow ,my teeth.....I can pull hard or soft , the energy being tranfered is the vibration .

When we spike our components it is to ground all the energy 100% of it from micro -air to micro -wire vibes.

If electricity was just that ....then no tweaking would be necessary . 15 amp and we would have a absolute exact sound everywhere.

Jim, sorry for the confusing attribution in my post. I am not Jim Aud of Purist Audio design. I was merely quoting something he explained to me over the phone a few months back.

My name is Neil.

I'm glad though, that the rest of my explanation was clear :~))

Jim, thanks so much for the great discription, and for taking the time out of your busy day. It is very clear to me now how it works.

Bill

Everything said so far is correct, but just so you won't be confused/misled when reading certain power cord descriptions, please note the following:

Quite often, cords are described as "20 amp" cords even though they have 15 amp hardware (plugs). This is because the wire conductors themselves are 20 amp capacity. The only reason I can think that cords are sometimes described this way is to indicate that they are capable of powering high loads (like big amplifiers.)

Most audio gear (except for a handful of "big mutha" amps) have 15A IEC receptacles. And most wall outlets are the standard 15A.

The use of 20A wall receptacles would probably provide you better contact area and a floating ground option (which I don't think you can get with 15A outlets). It would also allow a bigger wire size for the house wiring. All these things can (possibly) improve performance. "Possibly" meaning, for instance, if you were over 25 feet from your main panel, you'd want to use maybe 8 AWG wiring in the wall to avoid voltage drops, and then you'd need to use 20A outlets to connect 8AWG wire.)

As Jea48 mentioned, 15A cord can be (as small as) 14AWG per conductor. And most code minimums for house wiring itself specify either 14 or 12 for 15A circuits and 12 or 10 for 20A circuits (usually the smaller of the two in each case.)

So, you may ask, why use cords with conductors that are bigger than what's in the wall? The answer is "Energy Transfer" And the more power a component consumes (amps) -- AND/OR -- a component's frequent need for "nano-bursts" of power (DACs are in this category) the more a bigger conductor size will contribute to improved sonics. OK, you say, but if my wall wiring is 12 AWG, what's the point of using a 10 AWG power cord?

Once again the answer is Energy Transfer. Let me state some obvious facts, and then try and provide an analogy: Alternating current is stored (in your wall) as a potential -- it doesn't do anything until you connect a load of some sort. BUT, that potential changes direction (polarity) 60 times a second. And the potential itself varies 60 times a second (from 0 volts to 120 volts) In other words, it's not really a "consumable" like natural gas, that gets burned up when it comes out the other end of the pipe (that would be more like direct current, where the battery eventually runs down ;~) No, AC just "sits there" and changes back and forth 60 times a second.

OK, so here's my lame analogy: let's say the house circuit is a reservoir (imagine the ocean) of energy that's constantly changing in pressure (potential) and direction (polarity) -- imagine the waves at the shore. When you plug your PC into the wall, it's like sticking a pipe into the ocean at the shoreline. The bigger that pipe is, the more accurately the potential and pressure at the other end (the component) will reflect what's going on in the ocean itself. OK, imagine the pipe gets smaller. The pressure at the other end is still the same, but if you use some of it to do some work, it'll take a second for the pressure to build back up (poor energh transfer). AND, if you add to that, the fact that the direction of the "pressure" (pushing in and pulling out) is supposed to change 60 times a second, then the smaller pipe is going to create a lag in polarity changing. That doesn't mean you're going to see 50Hz AC instead of 60Hz, it means that spots of frequency cancellation are created in the "pipe" which further keep the available potential (pressure) from being realized at the other end.

Moral of the story: Especially with 15A wall circuits (as opposed to 20A) and except for low power stuff (like TTs, phono preamps, tuners, cassette decks, CDTs, not DACS) use the biggest sized conductor power cords you can, even sacrificing fancy shielding and insulation for conductor size if you have to.

"It's all about energy transfer." -- Jim Aud, Purist Audio Design

.

Thanks for the info and quick response. This site as always, is awesum!

Bill

The 15 amp cord will have a NEMA 5-15P plug on one end and a IEC 15 amp receptacle on the other end.
The nema 5-15P plug will plug into a 15 or 20 receptacle. The 15 amp IEC receptacle will only plug into a 15 amp IEC plug on a piece of equipment. The wire in the cord usually is 14 awg.

The 20 amp cord will have a NEMA 5-20P plug on one end and a 20 amp IEC receptacle on the other end. The awg wire size will be #12.
The NEMA 5-20P plug will only plug into a 20 amp receptacle (5-20R).
(The Neutral blade is at a right angle to the Hot blade of the plug)
The IEC connector on the other end will be a 20 amp receptacle and will only plug into a 20 amp IEC plug on the equipment.

Below is a link for picture purposes only. Check out picture numbers 4, 5, and 6
http://www.jenatek.com/pages/powercords.html

In most household circuits, 15A is the maximum current usually available in the circuit. Your audio equipment won't draw that much current, so there won't be a difference between a 15A cord and a 20A cord as far as audio equipment goes.

An example of where a 20A circuit/cord would be necessary are some of the cheaper Arc Welders, which use 115V, but 20Amps due to the fact that they are very high current devices.

The only Possible difference for stereo equipment is the fact that 20A cords are thicker than 15A Cords, and therefore MIGHT sound better. But I doubt you will hear a difference.

A better choice would be to replace (if interested) your stock power cords with, say, some of the power cords sold here on Audiogon that while still 15A rated, are made of better materials than the cheap cords that come with the equipment. This may or may not make a sonic difference. YMMV.