Did I not explain it very well?
 

In message , Ian Field
writes

"Dave Plowman (News)" wrote in message
...
In article ,
John Weston wrote:
I agree with you there Bill, never rely on an RCD. If the load, i.e.
you, is between L and N then the RCD will not see it as a problem and
give you a full load current dose. A child using two "probes" is as
likely to choose the L-N holes to play with, especially if they use a
protector cover to open the shutters as described elsewhere.

If a child can switch on a socket and then insert probes into line and
neutral after defeating the shutter, best let him fry.


Reminds me of a Dilbert cartoon:

As a young child Dilbert is taken by his mother to a shrink, the shrink
can't fully diagnose him because the intelligence analyser machine is
broken.

While his mother and the shrink are discussing his case, Dilbert starts
tinkering with the machine and gets it going - the shrink prononces "my god
he's got the knack", his mother pleads "you don't mean..........!", the
shrink replies "yes - he's going to be an engineer".

Dilbert's mother breaks down sobbing inconsolably.

http://www.youtube.com/watch?v=FlJsP...feature=fvwrel
--
Ian

Did I not explain it very well?
 

On Sat, 26 Mar 2011 13:24:18 +0000 (GMT), Jim Lesurf
wrote:


And decisions like "to use 'nuclear' energy or not" aren't purely matters
of science and engineering. They also involve judgements about risks, and
the costs and details to be chosen (or not). So quite a lot of political,
social, and economic judgement and 'soft' choices about which option is
worth choosing or to be avoided.

Yes.

Of course engineering does include a substantial amount of risk
assessment and risk management as a normal part of the discipline.

This is certainly the case with structural and chemical engineering.

However, with chemical, biological and nuclear plants there are wider
consequences of a plant going Kerboom! and spreading nastiness all over
the place. The experts who can understand the effects of such nastiness
are not the engineers designing the plant. There needs to be effective
cooperation and mutual understanding between all involved.


Even if a decision was sensible at the time, others later can come along
and change things in a way the original decision-maker may not have
expected. And of course you have to expect the unexpected. Sod's Law still
rules. :-)

The Twin Towers of the World Trade Center in New York were designed to
survive a hit from an airliner. Unfortunately airliners got much heavier
after the building was completed.

--
Peter Duncanson
(in uk.tech.digital-tv)

Did I not explain it very well?
 

In message , Peter Duncanson
writes
On Sat, 26 Mar 2011 13:24:18 +0000 (GMT), Jim Lesurf
wrote:


And decisions like "to use 'nuclear' energy or not" aren't purely matters
of science and engineering. They also involve judgements about risks, and
the costs and details to be chosen (or not). So quite a lot of political,
social, and economic judgement and 'soft' choices about which option is
worth choosing or to be avoided.

Yes.

Of course engineering does include a substantial amount of risk
assessment and risk management as a normal part of the discipline.

This is certainly the case with structural and chemical engineering.

However, with chemical, biological and nuclear plants there are wider
consequences of a plant going Kerboom! and spreading nastiness all over
the place. The experts who can understand the effects of such nastiness
are not the engineers designing the plant. There needs to be effective
cooperation and mutual understanding between all involved.


Even if a decision was sensible at the time, others later can come along
and change things in a way the original decision-maker may not have
expected. And of course you have to expect the unexpected. Sod's Law still
rules. :-)

The Twin Towers of the World Trade Center in New York were designed to
survive a hit from an airliner. Unfortunately airliners got much heavier
after the building was completed.

Both survived the impact OK. It was the subsequent fires, made worse by
the fact that both planes were full of fuel, that caused the collapse.
--
Ian

Did I not explain it very well?
 

On Sat, 26 Mar 2011 17:42:35 +0000, Ian Jackson
wrote:

In message , Peter Duncanson
writes
On Sat, 26 Mar 2011 13:24:18 +0000 (GMT), Jim Lesurf
wrote:


And decisions like "to use 'nuclear' energy or not" aren't purely matters
of science and engineering. They also involve judgements about risks, and
the costs and details to be chosen (or not). So quite a lot of political,
social, and economic judgement and 'soft' choices about which option is
worth choosing or to be avoided.

Yes.

Of course engineering does include a substantial amount of risk
assessment and risk management as a normal part of the discipline.

This is certainly the case with structural and chemical engineering.

However, with chemical, biological and nuclear plants there are wider
consequences of a plant going Kerboom! and spreading nastiness all over
the place. The experts who can understand the effects of such nastiness
are not the engineers designing the plant. There needs to be effective
cooperation and mutual understanding between all involved.


Even if a decision was sensible at the time, others later can come along
and change things in a way the original decision-maker may not have
expected. And of course you have to expect the unexpected. Sod's Law still
rules. :-)

The Twin Towers of the World Trade Center in New York were designed to
survive a hit from an airliner. Unfortunately airliners got much heavier
after the building was completed.

Both survived the impact OK. It was the subsequent fires, made worse by
the fact that both planes were full of fuel, that caused the collapse.

Yes. What I haven't seen said anywhere is whether a lighter aircraft
would have penetrated the building in the same way as those did rather
than crumpling and most of the plane crashing to the ground.

--
Peter Duncanson
(in uk.tech.digital-tv)

Did I not explain it very well?
 

On Sat, 26 Mar 2011 17:49:34 +0000, Peter Duncanson
wrote:

On Sat, 26 Mar 2011 17:42:35 +0000, Ian Jackson
wrote:


[Twin Towers of the World Trade Center]

Both survived the impact OK. It was the subsequent fires, made worse by
the fact that both planes were full of fuel, that caused the collapse.

Yes. What I haven't seen said anywhere is whether a lighter aircraft
would have penetrated the building in the same way as those did rather
than crumpling and most of the plane crashing to the ground.

By "lighter aircraft" I mean a smaller airliner not a light aircraft.

--
Peter Duncanson
(in uk.tech.digital-tv)

Did I not explain it very well?
 

"Peter Duncanson" wrote in message
...
On Sat, 26 Mar 2011 17:42:35 +0000, Ian Jackson
wrote:

In message , Peter Duncanson
writes
On Sat, 26 Mar 2011 13:24:18 +0000 (GMT), Jim Lesurf
wrote:


And decisions like "to use 'nuclear' energy or not" aren't purely
matters
of science and engineering. They also involve judgements about risks,
and
the costs and details to be chosen (or not). So quite a lot of
political,
social, and economic judgement and 'soft' choices about which option is
worth choosing or to be avoided.

Yes.

Of course engineering does include a substantial amount of risk
assessment and risk management as a normal part of the discipline.

This is certainly the case with structural and chemical engineering.

However, with chemical, biological and nuclear plants there are wider
consequences of a plant going Kerboom! and spreading nastiness all over
the place. The experts who can understand the effects of such nastiness
are not the engineers designing the plant. There needs to be effective
cooperation and mutual understanding between all involved.


Even if a decision was sensible at the time, others later can come along
and change things in a way the original decision-maker may not have
expected. And of course you have to expect the unexpected. Sod's Law
still
rules. :-)

The Twin Towers of the World Trade Center in New York were designed to
survive a hit from an airliner. Unfortunately airliners got much heavier
after the building was completed.

Both survived the impact OK. It was the subsequent fires, made worse by
the fact that both planes were full of fuel, that caused the collapse.

Yes. What I haven't seen said anywhere is whether a lighter aircraft
would have penetrated the building in the same way as those did rather
than crumpling and most of the plane crashing to the ground.


One documentary said the engines punched through the outer walls like
bullets (they weigh 4 tons each apparently) and destroyed fireproof cladding
that was supposed to protect the steel structure.

Did I not explain it very well?
 

"Steve Thackery" wrote in message ...
Mark Carver wrote:

It's the 'Euro' 2-pin plugs that you can, with care (don't try this at home) stuff into a UK 13A socket, I've watched countless
foreigners do it !

Yeah, but I'm not yet convinced Dave P is right. I don't think you get both systems combined on "most decent sockets". If I'm
wrong, though, then I'll have learned something new today.

STeveT

He is right but it's by accident rather than design.
it's the thin pinned europlug that fits, not what's on your UK shaver or toothbrush.
With most 13A socket you need to open the shutter with something poked into the earth
but with any MK socket made after about 1975 the shutter will open when the 2 pin plug is
inserted "normally"

MK plugs and sockets are generally regarded as amongst the best and safest available
so it's a bit ironic.

Apart from the possibility of damaging the socket, there is the small issue of lack
of a sensibly rated fuse, a ring main is typically fused at 30 amps which will make
a big bang if shortcircuted by a fault.

--
Graham.

%Profound_observation%

Did I not explain it very well?
 

"Dave Plowman (News)" wrote in message
...
In article ,
Mark Carver wrote:
Steve Thackery wrote:
Dave Plowman (News) wrote:

Two shutters that need both line and neutral pins inserted at the same
time to clear them. To allow the use of low current two pin shaver etc
plugs.

Hang on, they don't fit in a three pin socket anyway, do they? Pin
spacing, size and shape are different.

It's the 'Euro' 2-pin plugs that you can, with care (don't try this at
home) stuff into a UK 13A socket, I've watched countless foreigners do
it !

They are designed for precisely this - low current apps anywhere in
Europe. But require the appropriate UK socket - not one with an earth pin
operated shutter. I thought all newish 13 amp sockets were like this -
about the same time as DP switching came in.

The UK system is not designed for this. No fuses - plug tops not to BS1363
(the plug top standard) and it requires a bit of force as the 2 pin Europlug
does not totally line up with the UK socket L&N holes. Anyone who sells an
appliance in the UK with just a Europlug fitted is waiting to endure the
wrath of their local Trading Standards for contravening the Plugs & Sockets
Regs.

Did I not explain it very well?
 

"Mark Carver" wrote in message
...
Ian Jackson wrote:


I've probably done it myself - but never since I experienced the effects
of the power distribution sockets at a certain large cable TV headend
having been effectively wrecked by someone plugging in equipment fitted
with 10A European plugs. There is a good (bad) chance that this will
permanently slightly splay the socket contacts (and it had).

I've see those 4 way strips etc made of soft ABS (or is it PVC ?) plastic
have their slots splayed by continual use of Euro plugs.

Of course some manufacturers of sockets take that one step further, if you
buy 4 way strips in Middle East and Asian countries, the L and N slots are
deliberately wider to allow you to stuff anything you like in !

Almost all of the ones of these I have tested have been lethal in more than
one way!

Did I not explain it very well?
 

Stephen wrote:
I knew a Hungarian car mechanic who refused to have a microwave oven
because he thought it was radioactive!

I even showed him a copy of the EM spectrum chart and pointed out where
microwaves were at the medium-high end of radio waves in comparison to IR
from his regular oven and radiation way over yonder beyond UV.
But radioactivity is ionising radiation. It won't appear on an EM spectrum
chart.

Bill

Actually Bill, it depends on what form the radioactivity is, if its alpha
(Helium nuclei) or beta (high speed electrons) then you are correct in
saying its not electromagnetic radiation.

Alpha radiation can be stopped with a sheet of paper, and Beta radiation can
be stopped by 3mm aluminium.

Now if the radiation is Gamma, then that is in fact electromagnetic, it will
have a wavelength and frequency in the region of 0.01 nanomeres and 10^19
Hz respectively.

This will require some serious amounts of lead and concrete to block.

Regards

Stephen

Thanks for that. Very clarifying! Funny how such a high frequency can
pass through solid materials.

What's the relationship between X Rays and gamma rays then?

Bill