Power cord 15amp and 20amp

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

>>"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.
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>>> "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

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.)

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.

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.)