Why choose 120 volts?

Jay Hennigan jay at west.net
Wed May 27 17:04:13 CDT 2009


david raistrick wrote:
> On Tue, 26 May 2009, Joe Greco wrote:
> 
>>> http://www.cdw.com/shop/products/default.aspx?edc=1036852
> 
>> Great, you're the latest person to invent a way to present a 5-15R that
>> offers something besides 120VAC.  This is neither new nor novel, but it
>> *is* dangerous and risky, and in no way "solves the problem."
> 
> No, this does NOT present 208v at a 5-15R.   Don't believe me, buy one 
> and put a voltmeter across it.

It indeed can and does present 208V (or 240v in some cases) to a 5-15R. 
  I use one of them for that purpose to power my laptop charger from the 
IEC power strips present in racks fed from 208v.

That cord is just an adapter with three copper wires.  Putting a 
voltmeter on its output will just measure what is present on its input. 
  That cord mated to an IEC cord in Europe will put 240v 50 Hz on the 
receptacle.  Mated to an IEC PDU on a 208v-wired rack, it will measure 
208v.

This is not necessarily dangerous, *IF* you are aware of it and don't 
leave it plugged in for someone unaware of the voltage present to use. 
Radio Shack sells an adapter from the Schucko round pin 240v receptacles 
to a 5-15R.  It works just fine for my laptop because the laptop power 
supply is *designed* to operate on any voltage from 100 to 240 volts. 
It would NOT work just fine if someone plugged in a 120v-only appliance.

If you leave that cord plugged in to a 208V-fed rack and walk away from 
it, there is a likelihood that someone else looking for a convenience 
outlet will discover it and plug something in.  If that "something" 
isn't happy with the 208v it gets, the magic smoke that is contained in 
the device will escape.  As we all know, once the smoke gets out, the 
device will stop functioning.

--
Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service  -  http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV




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