Which wires are which?

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  #1  
Old 08-23-04, 05:28 AM
Tommy1
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Which wires are which?

Hi, i live in England and have just bought an American Mp3 player over the internet, when it arrived it came with an American plug so could someone please tell me which wires are live and neutral, the only indication i have is one wire is smooth and the other has a kind of corragated feel to it.
thanks for your help
 
  #2  
Old 08-23-04, 05:41 AM
W
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We need to know more.

Is the power supply for the player a 'universal' supply capable of operating at 240V? US voltage is only 120V, and the UK 240V will smoke many US devices.

Does the power supply have a detachable cord?

If you detach the cord, can you reverse it and plug it back in the other way?

Looking at the plug end, are the two blades the same or different? Is one blade wider than the other, or does it have little sideways extensions that would require a larger slot to fit it?

Most 'universal' power supplies used for things like laptop computers are fully isolated and don't care about hot versus neutral. Remember that alternating current as supplied in homes is _changing polarity_ many times per second. As far as the AC load itself is concerned, 'live' and 'neutral' are exactly the same. The terms 'live' 'neutral' and 'ground' are only relevant with respect to _safety_ of people external to the device and external voltage reference between devices.

If your power supply accepts a detachable cord, then the correct way to deal with this is to get a proper cord with a UK end.

-Jon
 
  #3  
Old 08-23-04, 05:47 AM
Tommy1
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Ye the plug is an american one with the two blades, and i need to plug it up to an english one with 3 blades. On the switch adapter it says its input can go up to 240 but i just need to know which wires are positive and negative. The "smooth and corrageted" is on the insulation by the way.
 
  #4  
Old 08-23-04, 05:51 AM
R
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There is no positive and negative. This is AC not DC. Positive and negative mean nothing.

If the two spade terminals are the same size then it does not matter which is connected to the hot wire and which is connected to the return.
 
  #5  
Old 08-23-04, 06:01 AM
W
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Please read what I wrote. I asked 4 questions. You answered 1. racraft is correct: if the input pins are the same, than the device is polarity insensitive. I just want to confirm that this is the case.

You will also need to figure out the proper fuse size to put into the cord cap. Switching power supplies can draw substantial inrush current, but you will need the fuse to protect the wires. US cords on small devices are designed to be protected by 20A circuit breakers...UK ring mains are often 32A breakers, and at 240V there is more voltage to push current through a fault. But this is why UK plugs have fuses in them.

-Jon
 
  #6  
Old 08-23-04, 02:43 PM
R
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Typically, the smooth wire is hot and the corrugated wire is neutral. However, if the two prongs are exactly equal in size, pay no attention to the difference in the wire texture. If the prongs are different sizes, then the larger would be the neutral and the smaller one would be hot.
 
  #7  
Old 08-23-04, 04:45 PM
Homer Simpson
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Good advice from a bunch of Yanks

Tommy,

The units sold in the usa are 60 HZ (cycles per second). I don't know what it
is in the UK, but I understand that there are countries in Europe that work
on 50 HZ.

This can be a problem with devices that use the ac signal frequency as a
reference. TV, camcorders, dvd player, etc. Thought I mention it.
Say goodbye, Homer. Goodbye
 
  #8  
Old 08-23-04, 05:30 PM
J
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If this is an adapter that convert line AC to DC the frequency won't matter.
The smooth side is normally the hot.
 
 

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