The Art of Unix Programming

Ian Molton spyro at f2s.com
Mon Feb 10 09:28:48 PST 2003


On Sat, 8 Feb 2003 21:07:45 +0000 (UTC)
andrius at tamos.net (Andrius Ciziunas) wrote:

> 
> 	lol!!....As for the voltage and frequency, I'm not sure...never
> heard why that's different....

Hmm. You've never seen a british plug then?

We have the BEST plugs in the world, bar none. And one of the safest
electricity systems, to boot, dsespite running at over double your
voltage...

You run at 60Hz. thats the ONLY thing you do better. I always thought
mains should be delivered at something like 6kHz or something, for
better efficiency, but still, lets continue...

You use spur-wired electrical systems - a bad idea, as you end up with a
number of cables carrying VERY VERY high currents. some of your domestic
cable is rated for over 60 Amps!

Apart from being very expensive on copper wire (you need thicker guage
wire), you can get some very dangerous failures, should a contact become
loose on one of the thicker wires, leading to arcing and heating
(possible fire) in the joint. The fact that you run at 110V makes this
even worse, as your devices draw twice the current ours do to do the
same job. Heating is related to the SQUARE of current, so a small
increase in current makes heating far worse.

Your plugs are *pathetic*. Look at my website
(http://www.mnementh.org/plugs/) for a side-by-side comparision of US
and UK plugs.

How you even DARE to rate these shitty plugs at 15A is beyond me. I have
seen them with the tips blown off, welded into the sockets, melted,
melted AND welded into the socket, and so on. This just DOES NOT happen
to a correcly wired UK plug (The meleted ones were not faulty US plugs,
just a testament to poor design).

your power cords for devices are often no thicker than ours, despite
running at twice the current (1/2 the voltage means 2x the current draw,
since powewr = voltage * current). Running an electric kettle in the US
will result in a power cord that is OFTEN warm to the touch afterwards.
A UK power cord is *COLD* after this sort of use, since we use cables
capable of carrying the required current, and the current is 1/2 that of
the US.

Your plugs are downright dangerous even when the havent melted. look at
the image on my website.

note that the earth (central) pin on our plugs is LONGER than the other
two pins (often not true of US plugs), and also note the thickness -
those pins can carry some serious current and do so with little
resistance!.

The two live pins (live (hot) and neutral (substation ground)) are also
very thick, but note the dark material for half their length - this is
an insulator, which prevents the pins from coming into contact with
humans untils they have disconnected from the socket elements (by law!).
the earth remains connected until both the main pins have disconnected.

The plug bodies are physically larger, and capable of dissipating a
not-unrepectable amount of heat before melting, thanks to their size. I
have NEVER seen a plug body that has melted, in 20 years, even poorly
wired ones.

The physical size also allows home users to SAFELY wire a plug, and
affords space for a mechanically SAFE cable-grip.

Also, ALL UK plugs contain fuses, which will blow in case of failure of
both device AND mains protection breakers. Often, a correctly rated fuse
(yes, some idiots put 13A fuses in 2A devices) will blow even if the
breaker goes, but thats extra safety, in any case, even if slightly
annoying to have to replace the fuse.

We use a RING main here, which means that the mains wire goes from the
breakers, to each socket, in turn, and then BACK to the breakers. We
allow 2x the current rating of the cable to be used IN TOTAL by all the
sockets on the ring, which is a little dubious in a failure case,
howver, you would find it hard to melt 15A cable at 240V (Ring rating is
30A total).

besides, if one socket in the ring has a poor connection, it wont
overheat, since it has another good connection, and so a low PD across
the poor contact.

This is FAR more critical than the current capacity of the cabling. the
cabling RARELY melts, however arcing in the socket is often a cause of
fire.
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