"Duncan Wood" wrote in message
news
On Wed, 06 Jun 2012 21:35:46 +0100, Sam Jones wrote:



"Phil W Lee" wrote in message
...
"Fevric J. Glandules" considered Wed, 6 Jun 2012
08:55:40 +0000 (UTC) the perfect time to write:

Phil W Lee wrote:

Our BS1363 fused plugs (and the sockets to match) are a masterpiece of
design,

As area denial weapons they have few equals, it is true.

Lego.

As plugs they have a couple of issues. As I understand it
the use of square pins requires a much higher contact force,

I'm not sure where you get that idea from.
All the round-pin designs I've used of similar current carrying
capacity have needed greater force, not less.
If there is anything that adds to the force required to insert or
remove BS1363 plugs, it is the shutter mechanism in the socket, which
I certainly wouldn't want to see removed.
Contact pressure makes almost no difference at all, although poor
quality plugs are likely to be more difficult to insert, as the pins
tend not to be profiled as accurately, particularly at the tips.

which in turn means that it's much harder to pull the plug
out, which
1) makes life more difficult for the elderly and / or arthritic

There are shaped plugs and plug pullers available for those with
special needs.

2) makes it more likely that the cable will pull out of the plug
rather than the plug out of the socket.

The plug is deliberately designed to make it very difficult to pull
out by yanking on the cable.
Again, cheap & nasty ones tend to be worse to remove, as they often
don't have a very good profile on the body of the plug, so are harder
to grip.

In the second case, this has the effect that if the plug is
badly wired, then the earth pulls out first rather than last.
And then has a good chance of making contact with one of the
others.

A good design would take into account lazy and / or incompetent
rewiring. It's no good saying "users ought to do this or that".
They won't.

Hence modern appliances almost all coming with moulded on plugs.
Fine until the cable frays or splits, and you need to replace it.
Then /someone/ needs to know how to wire a plug properly,

Not with cables with a plug on each end.


There's not much one can do to stop people who are incompetent enough to
make mains leads with plugs on both ends from doing stupid things.

I meant the sort of cable you get with a computer and many small appliances.

and because
moulded plugs have made this a rarer skill, it becomes more likely
that the appliance will be operated with a frayed and dangerous cable.