Re: Electrical Wire Safety

[Brian Whatcott <betwys1@SBCGLOBAL.NET>]

Single Wire, Earth Return [SWER]  systems are the bicycles of
 the World's (power) Transport system.    They are used where
the lowest cost method must be chosen to serve very low density
 rural routes abroad.

 Though the Earth return is said to be carried along a wide area
cross section of terrain,  the domestic feeds are in the usual form:
transformer  line outputs with a grounded neutral center-tap.
 This slide-show gives the general idea:
    <http://www.stonepower.se/Images/SWER.pdf>

Brian W

At 12:45 PM 3/12/2004, you wrote:
> Brian,
>
> More information please, so we can hope to evaluate your statement.
>
> Thanks
>
> Joel
>
> | -----Original Message-----
> | From: Forum for Physics Educators [mailto:PHYS-L@lists.nau.edu] On Behalf
> | Of Brian Whatcott
> | Sent: Friday, March 12, 2004 12:24 PM
> | To: PHYS-L@lists.nau.edu
> | Subject: Re: Electrical Wire Safety
> |
> | At 11:14 AM 3/12/2004, John D., you wrote:
> | >Quoting "Edmiston, Mike" <edmiston@BLUFFTON.EDU>:
> | >...
> | >Speaking specifically about the _distribution_ system i.e.
> | >the ~17kV stuff that killed the local pool-maintenance guy,
> | >the answer is simple: less cost, i.e. one wire instead of two.
> | >...
> | >The earth-return system is not just a cheap trick, it is a
> | >dirty trick.  In many locales, the conductivity of the dirt
> | >is not large compared to the conductivity of underground
> | >pipes.
> | ...
> | > > Today we can detect faults with GFCI devices.
> | > > These work independently of whether the system is
> | > > grounded or not by comparing the current in the
> | > > two wires to the device, and breaking the circuit
> | > > if the two currents are not equal-opposite.
> | >
> | >Not quite.  That would work with a two-wire system
> | >(more precisely, a wire-return system, as opposed to
> | >an earth-return system) whether or not one side of
> | >the system was grounded.
> | >
> | >A GFCI cannot possibly work with an earth-return system.
> |
> |
> | I think John is on doubtful ground, when talking about 1 wire
> | power distribution. The references I have don't confirm him.
> |
> |
> | Brian Whatcott    Altus OK    Eureka!


Brian Whatcott    Altus OK    Eureka!