"John Rumm" wrote in message
o.uk...
On 06/01/2012 20:47, dennis@home wrote:


"John Rumm" wrote in message
...

Try and comprehend, this has nothing to do with the user, and
everything to do with the designer and installer. If the designer does
their job right, the user can get on and use a system that is
flexible, does what they need, does not give spurious trips. and
remains safe.

Try and comprehend that the designer is putting in a system that will be
in place for decades.

Indeed, not that it makes much difference...

If you start with the premise that with a new installation, all the
circuits are fundamentally sound. What needs to be addressed with the
design is making sure there is adequate provision of sockets etc, in the
places they are likely to be needed, and that the circuits selected are
appropriate.

That means where you put sockets, and how many you install will reflect
the anticipated use.

If there is only one logical place in a kitchen to stick a fridge/freezer,
then that would be a good place to stick the non RCD protected socket with
the "Freezer Only" label on it.

The users will die (hopefully not from design faults), other users will
arrive, the designer has no idea what they will do in 5 years time let
alone 50.

The kitchen will still be the kitchen, so the same basic provisions will
be required. If there is a 1200mm wide gap under a worktop, with two sets
of washing machine taps, two drainage stand pipes, and a tumble drier
vent, its still a pretty good guess that a couple of remotely switched
sockets under there are going to be equally handy in 30 years as they are
now.

Likewise 4 or 6 doubles in the corner of the lounge adjacent to the TV
aerial socket is also going to be a safe bet.

All of your so called good design ideas have problems that get worse
with time, you know minor things like undetectable faults developing.

Tis why I prefer to use more fault tolerant circuits in the first place.

Any engineer would recognise these problems and avoid them where
possible, not just follow some *minimum* standard that needs revising.
No, sorry, I meant has been revised several times due to the minimums it
set being too minimum to be safe.
You can assume the current (pun intended) minimums are OK but I expect
them to be revised in my direction not to stay where you think they
should be,


You might like to mandate that a 32A circuit is dedicated to each and
every double socket, but fortunately its not your decision, and no one
else thinks its a good idea. So you may as well learn to live with it.

As a designer one has the freedom to make sensible choices about
matching the installation to the pattern of use. This is a system that
works remarkably well in practice, and has given the UK the safest
electrical systems in the world.

If you are still unhappy about it, why not write to the IET with your
objections and suggestions for the 18th edition? No point moaning
about it here.

You moan about it, I just don't do minimums to save a few pence.

You mean install a couple of 20A radials where an electrician would place
a 32A ring circuit? Cost is about the same, but the ring circuit will be
less likely to cause the user problems with nuisance trips because they
plugged the wrong combination of appliances into a set of sockets. The
radials are also more likely to be subject to long term low level
overload - something that the designer is supposed to mitigate against.

Use 4mm^2 cable instead of 2.5mm^2? Harder to wire, costs more, performs
the same. So why bother?

You still don't get it.. you want to work to the minimum standards, I don't.
You can do as you wish.
There is no need for the regs to change to make things better, all it takes
is a bit of thought.
I notice you don't mention putting a 20A breaker in the ring and getting all
the benefits of a ring and having less problems with faults.