Why choose 120 volts?

Dave Larter dave at stayonline.com
Wed May 27 17:39:37 CDT 2009


The ground is not supposed to carry any current where as the neutral is.
If you tried to carry current on the ground of a CGFI protected circuit
it would trip. 

-----Original Message-----
From: david raistrick [mailto:drais at icantclick.org] 
Sent: Wednesday, May 27, 2009 6:30 PM
To: Seth Mattinen
Cc: nanog at nanog.org
Subject: Re: Why choose 120 volts?

On Wed, 27 May 2009, Seth Mattinen wrote:

> Here's the L-G voltage off the 208v taps from an isolation transformer
in a 
> system with no neutral: http://ninjamonkey.us/not_120_volts.jpg

Not 120, but 90 give or take.  90 is at the low end of the acceptable 
range for common household 110/120v service.

Depending on how the phases are balanced in your facility, you may see 
that fluctuate up or down, of course.  If you measure hot to hot on the 
same PDU, do you get anywhere close to 208?  I'm going to suspect either

your fairly out of balance, or you've got a good bit of voltage drop by 
the time it arrives....


But since the concensus from those who haven't used this is that the 
device will present 208/240 at the 5-15 plug, I withdraw my suggestion
and 
leave you to your own methods.   (for the rest, test it yourself)

I also won't argue using ground for neutral, that's like arguing bonded
vs 
unbonded panels.



---
david raistrick        http://www.netmeister.org/news/learn2quote.html
drais at icantclick.org             http://www.expita.com/nomime.html






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