At 01:07 AM 8/12/2005 +1200, you wrote:
> > No, all fixed wiring is solid core in the UK (known as "twin
> > and earth").  Stranded wiring is only use for appliance "flex"
>
>Does the "skin effect" come into play with solid (single strand)
>cable ? Undoubtedly the power company engineers know a
>heap more about this than I do, just wondered if there was any
>significant advantage to using multi-strand (Litz) cable, cf power
>transmission over long distances by DC rather than AC

Yes, it does come into play, even at 60Hz, but only with rather fat
conductors.

The "skin depth" of copper at 60Hz is about 1/3", so a
1" diameter copper bus bar would behave about the same as a hollow
1" diameter tube with 1/3" wall thickness. They use copper-clad steel
cables, partly for this reason. The really high resistivity steel core
is there for the strength, and because it wouldn't do anything
useful electrically if it was copper.

Of course, as you mention, a lot of really high power lines are DC.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
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