Existential Angst wrote:
"Jules" wrote in message
news
On Mon, 26 Oct 2009 23:04:48 -0700, terry wrote:

(http://en.wikipedia.org/wiki/Ring_circuit for the curious)

That was VERY inneresting!!!
Am I correct in observing that the diagram shows two "radial" connections to
the ring?

The text talks about "unfused spurs".

It took me a while to grok the "point" of the schematic, and when I did, it
left me with a very big Q:

How does a ring circuit SAVE copper? ?
Yeah, I can see how you can use thinner gauge wire, but now you have to use
twice as much of it!

If you went straight out to a load and straight back there would be
twice the wire. The circuit wanders around the building picking up loads
as it goes.

Current capacity (density) is directly proportional to cross-sectional
area, so it seems to me this system is 6 of one, half a dozen of the other,
mass-wise in copper.
The article pointed out some potent disadvantages, as well -- somewhat
dicey, eh?

Seems really weird from the perspective of the US. Must be quite
reliable because it is still being used. I was really surprised when I
heard how different UK wiring is.

Interestingly, NYC still has DC running to some older commercial buildings!

Ended about 2 years ago.
http://cityroom.blogs.nytimes.com/2007/11/14/off-goes-the-power-current-started-by-thomas-edison/

And, NYC's 3 phase is 208, not 220 or 240 V, like most of the rest of the
country -- 208 is EXACTLY the rms voltage difference between two 120 V sine
waves 120 deg out of phase, making it, I think, the "purest" type of 3
phase.

The vast majority of 3 phase power in the US (that supplies 120V loads)
is 208V (wye connection). New 240V (delta connection) systems are
probably quite uncommon.

--
bud--