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[OM] Re: [OT] UK Plugs

Subject: [OM] Re: [OT] UK Plugs
From: "Jon Mitchell" <jon@xxxxxxxxxxxxxx>
Date: Fri, 12 Sep 2003 18:19:11 +0100
Hi,

(Read to the bottom, as there is actually some humour after the rant !)

Someone's already probably mentioned several times but here goes ....

Our 13amp UK power plugs are big because :

1) Each plug is individually fused.  This adds to the safety of our system.

2) The Earth pin enters the plug socket first (hence it's longer) as this
pushes aside the "door" on the Live and Neutral pins.  This means that the
Live and Neutral "holes" on the wall-socket are not exposed when a plug is
not in the socket (stops little kids shoving knitting needles in the socket
!).

3) Not sure that the links shown particularly showed it, but the Live and
Neutral pins of the plug are actually shielded in an insulating layer on the
half of them closest to the plug body.  This means that if a plug is only
half-in the socket, you can't electrocute yourself by putting fingers around
the back of the plug to pull it out.

I'm sure there are many other reasons / safety features but those are the
first 3 that sprang to mind.  A lot of it could be said to be excessive, (or
avoiding Darwin's theory of natural selection !), but I'm sure some of it is
driven by the desire of manufacturers of these things not to get sued !!



<rant mode on>
Whilst I'm not averse to the good ideas that come out of Europe, and the way
that we are being "encouraged" to have the same standards across europe, it
seems that too often we are being ridden rough-shod over to take-up a
standard that suits the rest of Europe with little or no regard for what is
best for us (read into that what you will !!).

For example, HiFi amplifiers here are not allowed to be sold with the
standard 4mm Banana Plugs on for Loudspeakers anymore, as someone in Europe
pointed out that one end of the cable could be accidentally shoved into one
of their round-pin manis sockets.  Forget the fact that you couldn't shove
one into our rectangular pin mains sockets without more effort than would be
required to build an adaptor for such a stupid connection.

The day they try to make us drop our 13amp mains plug system in favour of
some other European system (many of which from what I've seen has no fuse on
individual plugs, and you can plug an appliance requiring an Earth into a
non-earthed socket !) will be a bad day indeed.

<rant mode off>



Now to add a little humour to the rant, and demonstrate the rediculous
nature of some of our own UK Safety Standards for such electrical
appliances, I relate the following ...

A couple of years ago, one of my housemates was working at a facility which
had an Electrical Compliance Testing department.  This department tested
very thoroughly to ensure that anything manufactured met all the most
stringent test criteria.  For entertainment, said Housemate designed and
built a device known locally as "the Ether-Killer".  This device consisted
of a British Standard 13amp Mains Plug, some Cat 5 ethernet cable, and an
RJ45 connector (as found on most network cards in PC's.

2-cores of the Cat 5 cable were wired to the Live pin of the 13amp mains
plug.  The other 2 cores were wired to the Neutral pin.  The other end of
the 12inch long piece of Cat 5 cable was crimp-connected in the usual manner
to the RJ45 connector.  Now this may seem unsafe to anyone with even the
mildest appreciation of the incompatabilities between 240volts/13amps at
50Hz and the standard 100MB/s ethernet signal.  Unfortunately, the
"Ether-Killer" passed every one of the stringent safety tests it was put
through.

Admittedly, there were no "operational" tests for such a device, primarily
because, I suspect, no-one thought that anyone would be stupid enough to
build such a thing !  Nonetheless, the visual inspection on the device was
passed as the wiring was all to the required standard.  The plug itself met
all British Standards.  The cable is, actually, double insulated so this too
was OK.  Then they started at the other end.  Yes, this was a perfectly
acceptable RJ45 connector.  Passed all the specs for RJ45 connections.
Cable was as specified category 5 cable, so no problems.

Now, to his credit the tester did point out the dangers of plugging the
device into the mains, but conceded that on the grounds that he couldn't
technically fail it on anything he had to pass it as safe !!  I wish I was
joking, but alas this all actually happened.  To this day, we have not yet
tried out the device.  I suspect the result of such an experiment to be
fairly loud, quite bright and blue in colour, and possibly a little smelly
too !!


Sorry.  I'm in an odd mood today.  I'll go away now and shout at passing
cars ....

Jon





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