On Tue, 13 Aug 2013 19:02:53 -0700, Erik wrote:

Hi all,

A couple of neighbors were bickering about this.

Lets say there is a 100' extension cord (with metal copper conductors)
energized by a live household 120V 60Hz outlet. Nothing is plugged into
the cord, and it's one without any indicator lights or ground fault
gimmicks. Said cord is dry, other than the typical indoor humidity of a
normal household garage.

How would one calculate the minuscule energy loss from such a static
conductor just sitting and radiating (and/or whatever).

I tend to agree with the one neighbor that there's bound 'some' loss...
but probably on the order of, oh maybe a penny's worth every few
centuries; but haven't a clue as how one would calculate something like
this, or even what loses would be involved.

Inquiring minds and all that... Thanks in advance!

There is loss in the cord.

It is teeny.

It is subject to so many manufacturing and environmental variables
(moisture, how many elephants are standing on the cord, what it's made
of, temperature, etc.) that calculating the losses would be as inaccurate
as they would be time consuming.

Measuring the losses could be done, but you'd have to do much more than
just measure the current into the cord, because most of that current is
reactive (meaning, it's from the capacitance, and doesn't actually
dissipate power).

Possibly the easiest way to measure the losses in the cord would be with
a calorimeter -- pile the cord up into a styrofoam cooler with a
thermometer (electronic, probably), let everything settle for days to
reach an even temperature, then measure the temperature rise in the
cooler with the cord plugged in, then estimate the thermal
characteristics of cord and cooler to figure out the power dissipated.

It'd be a good senior project for a techno-dweeb with a sense of humor.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com