Re: Measuring impedance of wall socket

Ben Bradley wrote: 
I've done this at my last two jobs, but the measurement was made at the service entrance,
and not at some wall socket.  Both times, the result was about 1/10 ohm (in the US, at 120
volts).  This is at 60 Hz.  Rene suggests that by asking for "impedance", the OP wanted to
know the result over a band of frequencies.  I didn't have the equipment for such a
measurement, but I did find a paper where someone had done it.  The result was a wildly
varying impedance vs frequency.



   I worked with X-10-type controls a while back. and I recall hearing
that "the" line impedance at 120kHz was 6 ohms. I never tested this
myself, but in retrospect, I (actually the guy who was designing the
hardware) should have.


Time out, to think about this.  How could there be a
single value?  Different sizes and lengths of conductors
can exist from circuit to circuit,  and different loads could
be connected on any given circuit or from circuit to circuit.
The circuits can be wired with NM, or AC or in conduit, etc.
Each junction causes an impedance bump, and the number of
junctions as well as their physical layout varies.  Attached
equipment could have LC line filters or be purely resistive.


I think the question has to be crisply defined to get a
definitive answer.

Ed



   You may find more info on power line impedance by researching power
line carrier (PLC).



John 


-----
http://www.mindspring.com/~benbradley

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