Mailinglist Archive: opensuse (3666 mails)

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Re: [SLE] PC Crash: Hard Disk Problems
  • From: "Carlos E. R." <robin1.listas@xxxxxxxxxx>
  • Date: Tue, 22 Mar 2005 14:00:13 +0100 (CET)
  • Message-id: <Pine.LNX.4.58.0503221347490.7275@xxxxxxxxxxxxxxxx>

The Monday 2005-03-21 at 17:49 -0800, Randall R Schulz wrote:

> I suppose a person could hold two appliances plugged into each outlet of
> such a split-phase duplex outlet box and both of those appliances could
> have faulty insulation and there could thus come to exist a current
> path from one phase to the other. How likely is that? Not very, but
> this _is_ the sort of situation to which Murphy's law applies (the
> failure mode was not excluded by the essential nature of the device or
> design, thus it must be expected to happen, eventually).
>
> Nonetheless, a GFCI in either or both of the outlets in the duplex pair
> would trip when that happened, right? The only thing that would
> persistently and unconditionally (and inappropriately) trip it was if
> you ran a single 240V appliance off the the pair of split-phase
> outlets. That would require jury-rigged wiring. In that case, the
> creative soul who tried to exploit the split-phase duplex outlet would
> deserve not to be able to turn his appliance on.

However, if you use a single GFCI, or differential switch, designed for
three wires (two live, one neutral); ie built with the three wires coiled
on the same iron nucleus, it will trigger in any combination of ground
fault you can imagine. It comes from kirchoff law: the sum of all currents
entering the house must be zero. If it isn't, it is because some current
is going some other way. Or body.

I was not aware of how your residential system was designed, with two
voltages, 180 degrees. Just for the record, I'll mention that here we
have, on homes, a single phase system, 220 or 240 depending on country.
It derives in fact from one of the 3 phases of a tri-phase transformers
(120 degrees, 380 Volts), which can be used for residential elevators
and relatively small industries.

This is of course, off topic. Lets imagine that we travel and need to know
how to connect our Linux computers on each country O;-)

--
Cheers,
Carlos Robinson


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