In uk.d-i-y, Wanderer wrote:

Did you bother to read this thread? I suggest you read my message i.d.
, where I set out my views
about the subject in more detail.

Fie, sir, fie and piffle, and piffle I say again. I've read this thread,
and one or two others too...

I am concerned that a complete novice attampting to follow an idiot's
guide to wiring alterations 'parrot fashion' will not have any
understanding or concept of the dangers inherrent in not carrying out
the works in a safe Manner. It is fashionable these days to say 'So
what? If the idiot kills himself or his family, tough luck.' I happen to
think that such incidents can and should be avoided.

It's extremely *un*fashionable to assert personal responsibility in this
way; it's far *more* fashionable to attempt to regulate beyond reason,
and thereby produce perverse incentives. In the particular case we're
discussing here - and have been discussing on and off for some months,
including group participants making detailed representations both at the
time the addition to Building Regs was being consulted on, and subsequently
to MPs, as you'd know if you'd been participating for longer than a
couple of weeks - those perverse incentives seem to be present in spades.
For one, it's companies, not individuals, who have the NICEIC blessing:
thuz, mumpties who learn a job by rote and mishearing get covered, while
competent people outside the club don't get a look in. For two, the
"minor works" exemption provides an incentive for the marginally
informed - e.g. those who pick up a cautiously-worded leaflet at a
d-i-y shed - to overextend existing circuits, 'cuz that's a Minor Work,
where it would have been better on grounds of circuit loading and fault
discrimination to put in a new final circuit. For three, it creates an
incentive for the small jobbing electrician to quote two rates for
a couple of socket-moves-for-the-old-lady-who-now-finds-it-hard-to-reach-down:
"40 quid cash, love, or 130 through the books; it's the Certificate, see",
which corrodes respect for the regulatory regime among both practitioners
and public. In the current state of affairs, as multiple years of postings
to uk.d-i-y bear out, there *is* respect for the Wiring Regs themselves:
many, possibly even most, "new" enquirers start out along the lines of
"I'm thinking of doing X, what do the Regs say?", or are at least happy
to take direction from the text of the OSG (it's typically queries at
the more practical level addressed by the OSG which arise, rather than
the general principles level of the Regs themselves).

Indeed, the existence of the OSG - and the many books of Regs commentary
/ application - undermine your general point about "attempting to
follow an idiot's guide ... 'parrot fashion'". The OSG, C&G courses, how-to
leaflets, electrical-practice sections of d-i-y books, and the like,
are all conservative renderings of the Regs, which themselves are more
"good engineering" than "basic science". Would you call the OSG's Table
7.1 an "idiot's guide"? (This is the one which gives maximum lengths
of 'conventional final circuits' - rings-n-radials - for different
combinations of cable composition and protective device.) Since it can
be *used* without doing the calculations of earth impedance - or even
understanding its significance, as you call for - do you condemn all
practicing sparkies who either use the table, or even more "sloppily"
carry around in their heads "2.5mmsq for domestic power", while quietly
knowing that (a) under boundary conditions 1.5mmsq or 4mmsq might be
get-away-with-able or necessary, respectively, and (b) not being too
sure *exactly* where those boundaries lie, but knowing roughly where
the point comes that more detailed circuit design needs doing? If so,
you're suggesting a degree of engineering micro-application which is
utterly impractical in an applied-trade occupation, whether undertaken
by a "competent tradesperson" or a d-i-y'er.

Taking your argument to its logical conclusion, I assume we can expect
to see you promoting do-it-yourself brain surgery! After all, if we
can't eliminate *all* risks, if we're prepared to adopt good sense, if
we're prepared to seek out all available information, if we're all
prepared to practice enlightened self-interest by performing surgery on
somebody else, if we're all prepared to use only the prescribed tools
and equipment for the job.......

Oh dear, the "logical conclusion" fallacy. As with most instances of it,
the alleged conclusion doesn't follow from the premises at all. Any mumpty
daft enough to try to engage in d-i-y brain surgery, be it on themselves
or on someone else, clearly hasn't "sought out all available information",
adopted good sense, or listened to any suppliers of tools and equipment
for the job. Do you seriously expect us to consider domestic electrical
wiring as requiring the same level of training and background scientific
knowledge as brain surgery?

Stefek