Polarity on a non-bladed plug?

>> I remember reading somewhere that the plug wire that has ridges on the side is the ground and the smooth side hot.<<
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As for the cord you are correct. Though the correct terminology for the side with the ridges is the "Grounded Conductor", (the neutral).
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AC Plug orientation. Post by Charles Hansen

SETTING UP YOUR SYSTEM:
AC POLARITY by MGD

Noise, hum and AC polarity.
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(quote)
1) Reversed AC polarity -- All power transformers have an inherent asymmetry to their construction. The primary winding comprises multiple layers, so that one lead is connected to the innermost windings and the other lead is connected to the outermost windings. This means that one lead has a higher coupling capacitance to the core of the transformer. Please remember that the AC supply is also asymmetrical, with the neutral lead essentially being at ground potential (assuming there is not a fault in the house wiring). The result is that one orientation will give a higher AC leakage current to the chassis of the amp (and worse sound) than the other orientation.

Not all transformer manufacturers use consistent markings on their transformers so that the correct orientation can be identified, and not all amp manufacturers pay attention to this even if the transformer is correctly marked. The result is that many audio products have a random chance of being correctly oriented.
Charles Hansen
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10-14-07: Inpepinnovations

while it might not make a difference sound wise, it might make a difference 'hum' wise. If no hum present, then I agree, since AC does not have 'polarity' as DC does.
Inpepinnovations

Bob, when we speak of ac polarity lets not confuse the issue by comparing it to that of DC polarity. In this case of AC polarity I am not talking about Current flow in a circuit.
When referring to AC polarity I am referring to an AC grounded system like that of your average home. Where, to keep it simple, the secondary winding of the utility transformer that is used to feed homes in a typical US neighborhood. The secondary of the transformer is called a split phase winding. Basically the single phase secondary winding is center tapped midway in the winding. The nominal voltage is 120/240V 3 wire power that is brought into your home. NEC, (National Electrical Code), requires that the service be an AC grounded system.

NEC requires the center tap conductor be intentionally bonded to earth ground by a minimum of two earth Grounding Electrodes.
The intentionally current carrying grounded conductor becomes the "Grounded Conductor", the Neutral.
NEC also requires the grounded neutral conductor to be bonded to the electrical panel enclosure. Final product, a single phase 3 wire AC grounded electrical power system. Two ungrounded conductors, L1 and L2, with a difference of potential between them of 240V nominal. With a difference of potential from either of the two Lines to the Grounded Conductor, of 120V nominal.

Now we can talk about AC polarity as it pertains to NEC.
NEC requires all 120V receptacles and lamp holders to be of the polarized type. A standard 120V receptacle, (NEMA 5-15R or 5-20R), is a 3 wire 120V polarized type receptacle. NEC requires the receptacle to have a white, silver, colour terminal screw for the neutral conductor. A brass, or similar colour screw for the hot ungrounded conductor. The equipment ground terminal screw green in colour.
Looking at the faceplate of a 5-15R, 15 amp, receptacle one female slot is longer than the other. The longer of the two is the grounded conductor, the neutral. In the case of the 5-20R, 20 amp, receptacle the longer of the two is a "T" slot, (the neutral). This is the correct polarity wiring configuration.

The reason that I wish to remind people that AC has no polarity is to rid them of the fallacy that there is only one direction for the current. This is not true, therefore all 'mumbo-jumbo' about assymetrical AC circuits and where the hot and ground leads (which are incorrectly referred to as positive and negative) are located making a difference in sound, such as the contention with the transformer leads, is just that, 'mumbo-jumbo'. Any difference to the sound due to reversing the plug is due to a change in the noise or hum which might appear at the audio line chassis connection, not transformer configuration of hot and ground connections being asymetrical, etc.
Respectfully, Bob P.
Inpepinnovations

Disagree..... You need to reread the link I provided by Charles Hansen. Think of the correct AC polarity orientation as I described it in my last post. Not as the current flow in the circuit changing direction 120 times per second....
Also think of the 120V AC grounded system in this way. The Hot Ungrounded conductor as the high side of the line and the Grounded Conductor (neutral) as the low side of the 120V line, with respect to earth ground. Some use the term hot and cold respectively.

These guys would also disagree with you.

Charles Hansen - Manufacturer, Ayre Acoustics, Inc.

rcrump - Manufacturer, TG Audio (deceased)

john curl - Manufacturer, Parasound, CTC

Nelson Pass- Manufacture, Pass Labs

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