I browsed a hobbyist electronics magazine today
[Practical Electronics May 2005]
and lit on an article spelling out uses for an LCR meter.
One measurement whose simplicity I had forgotten
was the characteristic impedence of cables.
What do think is the characteristic impedance of a 3 wire
mains extension cable?
I had one at hand: the capacitance of the leads measured
459pF / 467pF / 469 pF
and with the far ends shorted two at a time, they measured
3.82 uH / 4.14 uH / 4.18 uH
The article noted the simple formula: Zo = sqrt[L/C]
which leads to values of Zo between 91 Ohms and 95 ohms.