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!