"John Rumm" wrote in message
...
On 30/05/2015 18:16, dennis@home wrote:
On 30/05/2015 17:21, John Rumm wrote:
On 30/05/2015 14:19, dennis@home wrote:
On 30/05/2015 01:03, John Rumm wrote:
On 29/05/2015 19:02, dennis@home wrote:
On 29/05/2015 11:20, John Rumm wrote:

All that is required is a bit of common sense from the designer of
the
circuit, and a user can do as they please.


So three 3kW heaters on the end of a ring then?

Which part about the designer using common sense did you not get?

If you have a kitchen layout like mine, all the sockets are in the
middle of the ring since there is a 20m of cable run just to get
there.
If you have a CU in the kitchen then you use a bit of common sense
like
if you have a pair of adjacent utility spaces close to one end of the
ring, you make sure you wire the sockets on alternate ends and not
adjacent to each other.

So you want to make it worse as the user now has no idea where the
"close to one end" sockets are?

Den, I know this is a personal crusade of yours to convince the world
there is a problem where it is blatantly obvious that one does not
exist, but at least try and put the effort in - rather than taking the
lazy route of simply being obtuse...

I will say it again for you:

The user has no need to know what socket it where in the cable run. They
plug stuff in, it works.

Now a designer ought to think about it a bit more deeply. They need to
think about what the typical loads are going to be, what the circuit
layout will be, and what type of circuits to provision. For general
purpose socket circuits this is often a ring, but it does not have to
be.

So a user has to know what design decisions have been made so he can
avoid doing something that compromises them.

The user will have to trust that the designer and installer had a clue, or
else they might risk having shorter than expected service life from their
cable or sockets.

Much the same as the user will trust that the mechanic made a proper job
on the brakes of their car, or that the surgeon really does know what he
is doing.

They will need to trust that the plumber did not override the safety
interlocks on their immersion heater, and that the gas fitter remembered
to still a screw in the flue coupling on their boiler.

That's the problem, you don't know what a user will do.
All you have been able to say is that typically a user wont compromise
the design but they still can, either by design or by accident.

If you think long and hard enough you can contrive ways in which a user
can abuse any system. No circuit topology or design is immune from abuse.
Hence you have to pick a compromise that is good enough in all likely
cases.


A common mistake that people make when trying to design something completely
foolproof is to underestimate the ingenuity of complete fools.

So it's not fool proof it's den proof:-)





--
Adam