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Re: [Amps] Safety grounding - was Mains Isolation Transformer

To: g3rzp@g3rzp.wanadoo.co.uk, r@somis.org
Subject: Re: [Amps] Safety grounding - was Mains Isolation Transformer
From: Gudguyham@aol.com
Date: Wed, 5 Jul 2006 11:10:39 EDT
List-post: <mailto:amps@contesting.com>
In a message dated 7/5/2006 10:54:09 AM Eastern Daylight Time,  
g3rzp@g3rzp.wanadoo.co.uk writes:

Only if the two loads have identical power factors. If one is capacitive  and 
one is inductive, the currents in the neutral won't  cancel.
OF COURSE

>in which case it would be a dead short which will throw the breaker in  a 
fraction of a second< 
OK. We have to consider the possible fault current during the time that the  
breaker takes to open (or not, sometimes!) Interestingly, there was a Boeing  
747-400 had a bit of a problem 10 years ago because Boeing mistakenly fitted a 
 25 amp breaker instead of 2.5Amp breaker, and the wiring couldn't handle the 
 fault current. So the fuses in out mains plugs have something  like a  
60kAmp fault breaking capability i.e. they can break a fault current of 60kA.  
They 
don't get long to do it, obviously!

73 
Peter G3RZP


Peter in your observation above, indeed that would be a problem since the  
breaker required and the breaker installed was a factor of 10 times.   Lou
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