Electrics: How much can I legally do myself?

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Chris Cowley

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Oct 3, 2002, 1:14:00 PM10/3/02
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I live in an old victorian house and all of the electrics, with the
exception of the few bits I've done myself (spur sockets, outside lights
and the like), are 1960's vintage.

I contacted the electricity board and had someone come around today to
quote me for replacing the shonky-looking fuseboards and moving the
meter from its current position inside the house to a box outside the
house (about 4 feet from its current position). I was expecting this to
cost maybe four or five hundred quid but I had a bit of a shock:-

Firstly, the electricity board will not move the meter until after I
have had a modern consumer unit fitted by an independent electrician;
they don't do this themselves, and the guy who visited said that any
electrician tasked with fitting a new consumer unit would also want to
(or possibly be obliged to?) rewire the house in order to bring it in
line with modern safety standards and requirements. The bottom line is
that in order to get the meter moved outside, I would have to fork out a
total of about 2,500 quid!

So my question is, can I legally replace the fuseboards with a consumer
unit myself or does this need to be done by some form of certified
electrician? I would like to do this myself if possible, and rewire the
house myself in stages in the future to fit in with other decorating
jobs.

Thanks in advance for any insight.
--
Chris Cowley

chris French

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Oct 3, 2002, 7:13:44 PM10/3/02
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In message <n8topu4mctov1a8i2...@hobgoblin.grok.co.uk>,
Chris Cowley <cco...@grok.co.uk> writes

>I live in an old victorian house and all of the electrics, with the
>exception of the few bits I've done myself (spur sockets, outside lights
>and the like), are 1960's vintage.
>
<snip>

>
>So my question is, can I legally replace the fuseboards with a consumer
>unit myself or does this need to be done by some form of certified
>electrician?

Yes you can do it yourself.

--
Chris French, Leeds

John Southern

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Oct 3, 2002, 8:24:50 PM10/3/02
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Yes if you think you can do it. Change the mains boards yerself and
update the final circuits if they really need it. Then call an
electrician to do a full fixed wiring 16th edition test.
If you have the original 60s wiring i think the lighting circuits will
need replacing because of no earth and you could have rubber sheated
cable.

John.

Chris Cowley

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Oct 4, 2002, 6:05:56 AM10/4/02
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On 3 Oct 2002 17:24:50 -0700, johna...@btinternet.com (John Southern)
wrote:

>Yes if you think you can do it. Change the mains boards yerself and
>update the final circuits if they really need it. Then call an
>electrician to do a full fixed wiring 16th edition test.

According so some e-mail responses I've had, it seems I might have
trouble getting a electrician to test my work as many won't test other
people's work. I'll have to find someone willing to do this and get a
price before I start.

>If you have the original 60s wiring i think the lighting circuits will
>need replacing because of no earth and you could have rubber sheated
>cable.

I checked some of the wiring this morning and the situation is not quite
as bad as I'd thought. The cable is plastic-sheathed and the lighting
circuits are earthed (solid green earth rather than green/yellow -- how
old does that make it?), so it seems it's just the fuseboards that are
ancient.

I may therefore get an electrician in to quote for fitting the consumer
unit, as I think the cost shouldn't be too excessive *if* the existing
wiring is okay for the 2 or 3 years it will probably take me to
gradually replace it all myself.
--
Chris Cowley

Dave Plowman

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Oct 4, 2002, 6:25:19 AM10/4/02
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In article <rdoqpu4o9ugj2202p...@hobgoblin.grok.co.uk>,

Chris Cowley <cco...@grok.co.uk> wrote:
> I checked some of the wiring this morning and the situation is not quite
> as bad as I'd thought. The cable is plastic-sheathed and the lighting
> circuits are earthed (solid green earth rather than green/yellow -- how
> old does that make it?), so it seems it's just the fuseboards that are
> ancient.

I presume you mean the earth sleeving on the TW&E earth? Have you checked
it's actually connected inside a ceiling rose? I've seen them connected at
the consumer unit end but not elsewhere...

Think green/yellow sleeving came out in the early '70s, but since a drum
of the stuff can last some time even with a busy electrician it's not
necessarily a hard guide.

--
* Proofread carefully to see if you any words out or mispeld something *

Dave Plowman dave....@argonet.co.uk London SW 12
RIP Acorn

Stefek Zaba

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Oct 4, 2002, 7:52:32 AM10/4/02
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In uk.d-i-y, Chris Cowley (cco...@grok.co.uk) wrote:

> According so some e-mail responses I've had, it seems I might have
> trouble getting a electrician to test my work as many won't test other
> people's work. I'll have to find someone willing to do this and get a
> price before I start.

Entirely at odds with my experience: local companies are usually very eager
to come and do a 16th Edn test for you for a fixed fee (50 quid); many
see this as a sales opportunity to tell you about mains-powered smoke
alarms, new final circuits, and lots of other things to make your electrical
life better (and incidentally profitable for them). You don't have to say
when you phone the outfit that you've done a load of d-i-y yourself and
just want an OK: rather, say "I've recently moved into this house and
would like an electrical inspection". When the electrician comes round,
assuming s/he is basically human, *that's* the time to ply with cups of
tea and do the Full Disclosure thing...

Stefek

Chris Cowley

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Oct 4, 2002, 8:08:47 AM10/4/02
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On Fri, 04 Oct 2002 11:25:19 +0100, Dave Plowman
<dave....@argonet.co.uk> wrote:

> I presume you mean the earth sleeving on the TW&E earth? Have you checked
>it's actually connected inside a ceiling rose? I've seen them connected at
>the consumer unit end but not elsewhere...

Well, funnily enough, I looked at two light fittings and found that one
was not connected although I'm not particularly concerned about this as
it's easy enough to sort out.

Actually that reminds me of another quick question. The upstairs sockets
appear to be on a radial circuit rather than a ring. I don't have any
particular problem with this, but what happens if I want to add an extra
socket in the future. Can I spur off an existing socket or would I need
to wire a new socket in between two existing ones to effectively extend
the radial circuit?
--
Chris Cowley

Dave Plowman

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Oct 4, 2002, 8:46:58 AM10/4/02
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In article <93vqpusjmtgro6abi...@hobgoblin.grok.co.uk>,

Chris Cowley <cco...@grok.co.uk> wrote:
> Actually that reminds me of another quick question. The upstairs sockets
> appear to be on a radial circuit rather than a ring. I don't have any
> particular problem with this, but what happens if I want to add an extra
> socket in the future. Can I spur off an existing socket or would I need
> to wire a new socket in between two existing ones to effectively extend
> the radial circuit?

A radial circuit should be on a 15 amp 'fuse' if wired in 2.5mm. Can't see
why adding an additional socket will be a problem - apart from the
existing loading restriction. If you *can* turn two radial circuits into
one ring and alter the CU to suit, this is the way I'd do it.

--
* The problem with the world is that everyone is a few drinks behind *

Stefek Zaba

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Oct 4, 2002, 11:07:10 AM10/4/02
to
In uk.d-i-y, Chris Cowley (cco...@grok.co.uk) wrote:

> Actually that reminds me of another quick question. The upstairs sockets
> appear to be on a radial circuit rather than a ring. I don't have any
> particular problem with this, but what happens if I want to add an extra
> socket in the future. Can I spur off an existing socket or would I need
> to wire a new socket in between two existing ones to effectively extend
> the radial circuit?
> --

*If* the radial is installed in line with current practice, then it's
simpler to extend than a ring: a 'conventional circuit' radial can have
as many branches as needed to supply an unlimited number of circuits for
the floor area it feeds.

The conventional circuit limits these days are:

- 50 sq m for a circuit fed with 2.5mmsq T&E, with a 20A MCB or fuse

- 75 sq m for a circuit fed with 4mmsq T&E, with a 30A or 32A MCB or
cartridge fuse (NOT a rewireable fuse)

Your installation may well predate those limits. If the existing feed is
2.5mmsq and is in decent enough condition, you'd be unlikely to make things
worse (he said, phrasing cautiously!) to convert it into a ring - find
the end of the radial and run another 2.5mmsq back from there to the
CU, so creating a ring; but you'd have to make sure that no more than
a single socket (double or single) branched off the was-a-radial-now-a-ring
for full compliance with 16th Ed practices, or that at least any spur had
no more than a couple of sockets on it for compliance with the previous
edition and basic good sense...

As Dave P mentions, it may make more sense to take a couple of radials,
join their ends, and run their starts from a single 30A way to create a
conventional ring. But this relies on the wiring of the radials being
in good nick, not having side-branches you can't readily incorporate
into the main ring, and the total floor area served not being vastly
over the 100 sq m recommendation of the current Regs.

HTH, Stefek

Andrew Gabriel

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Oct 4, 2002, 11:37:02 AM10/4/02
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In article <rdoqpu4o9ugj2202p...@hobgoblin.grok.co.uk>,

Chris Cowley <cco...@grok.co.uk> writes:
> On 3 Oct 2002 17:24:50 -0700, johna...@btinternet.com (John Southern)
> wrote:
>
>>Yes if you think you can do it. Change the mains boards yerself and
>>update the final circuits if they really need it. Then call an
>>electrician to do a full fixed wiring 16th edition test.
>
> According so some e-mail responses I've had, it seems I might have
> trouble getting a electrician to test my work as many won't test other
> people's work.

I think the reason you give is wrong. The big problem is there are
just nowhere near enough electricians in some parts of the country
(parts of the South East certainly). I have many colleagues/friends
who just give up in dispair as one after another electrician just
doesn't turn up for a job, because they found something better to do.
I was listening to a program on Radio 4 whilst driving from one office
to another a few weeks ago, and the owner of an electrical company was
being interviewed. He said that they can no longer get anyone to join
the trade. School leavers with the necessary maths and engineering
aptitude simply never consider entering that type of trade any more,
and those who do try to enter are completely lacking these elementary
skills and are unsuitable. Apparently, this problem is rapidly getting
worse.

I have occasionally had offers of free testing from Southern Electric
contracting (i.e. the former electricity board engineering staff).
Of course, that's meant to be a foot-in-the-door for a complete rewire.

--
Andrew Gabriel
Consultant Software Engineer

Chris Cowley

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Oct 4, 2002, 1:10:23 PM10/4/02
to
On 4 Oct 2002 15:07:10 GMT, sj...@hplb.hpl.hp.com (Stefek Zaba) wrote:

>As Dave P mentions, it may make more sense to take a couple of radials,
>join their ends, and run their starts from a single 30A way to create a
>conventional ring. But this relies on the wiring of the radials being
>in good nick, not having side-branches you can't readily incorporate
>into the main ring, and the total floor area served not being vastly
>over the 100 sq m recommendation of the current Regs.

Okay, thanks Stefek and everyone else who's responded -- it's certainly
given me plenty to think about! My current plan of action is to firstly
figure out exactly what the current layout is (there are three
fuseboards with various bits of ageing bakelite and porcelain cack
screwed to them) then, assuming the existing circuits are in reasonable
order, I'll fit the new consumer unit (or possibly get it fitted by an
electrician) to work with the existing layout, and finally replace the
wiring in stages so I end up with two lighting circuits (upstairs and
downstairs) and two ring circuits (again one upstairs and one
downstairs). That seems to be the most sensible layout. Finally I'll
contact SEEBOARD again and see if I can get the meter moved outside
(which was really the original point of the whole exercise!).

Of course, that could all change if I discover any lurking horrors (a
distinct possibility, I should think).
--
Chris Cowley

Steve Dawson

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Oct 4, 2002, 1:59:43 PM10/4/02
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"Andrew Gabriel" <and...@cucumber.demon.co.uk> wrote in message
news:ankciu$39v$1...@new-usenet.uk.sun.com...

Your free test would be a visual inspection by a sales rep.

Steve Dawson


K

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Oct 4, 2002, 6:36:43 PM10/4/02
to
In article Chris Cowley <cco...@grok.co.uk> writes

>I live in an old victorian house and all of the electrics, with the
>exception of the few bits I've done myself (spur sockets, outside lights
>and the like), are 1960's vintage.
>
>I contacted the electricity board and had someone come around today to
>quote me for replacing the shonky-looking fuseboards and moving the
>meter from its current position inside the house to a box outside the
>house (about 4 feet from its current position). I was expecting this to
>cost maybe four or five hundred quid but I had a bit of a shock:-
>
>Firstly, the electricity board will not move the meter until after I
>have had a modern consumer unit fitted by an independent electrician;
>they don't do this themselves, and the guy who visited said that any
>electrician tasked with fitting a new consumer unit would also want to
>(or possibly be obliged to?) rewire the house in order to bring it in
>line with modern safety standards and requirements. The bottom line is
>that in order to get the meter moved outside, I would have to fork out a
>total of about 2,500 quid!

>
>So my question is, can I legally replace the fuseboards with a consumer
>unit myself

Yes, provided it is purely domestic & there is no hint of commercial use
(eg letting to tenants) & you are in E&W (refer to local Building Regs
if you're in Scotland) & you're not being paid to do the work.

Any hint of a commercial/industrial aspect & you almost certainly need
to be recognized as 'competent': usually evidenced by having passed
relevant C&G tests; & perhaps insured.

This scenario is set to change - the proposed Part P of the Building
Regs will bring all domestic electric wiring, of whatever sort, within
the B Regs. Implementation date guess: could be 4/2004 but
sooner/later/never possible. After that you will almost certainly need
to employ an NICEIC or ECA electrician ie DIY will be virtually
impossible.

> or does this need to be done by some form of certified
>electrician?

most electricians aren't members of NICEIC or ECA, but that doesn't mean
they aren't competent, nor that ones without a certificate are naff.
Ask around for a recommendation from satisfied customers.

> I would like to do this myself if possible, and rewire the
>house myself in stages in the future to fit in with other decorating
>jobs.

I'd say the complexity of the task - work & knowledge - is comparable
with designing & installing A CH system. A lot of the reasoning
involved is similar except it is electricity instead of heat. ie not too
hard if you have a reasonable technical background, are mechanically
adept and got on OK with physics at school.

With electricity it is more vital that you're not error prone and are a
trifle risk averse - ANY VOLTAGE OVER 40v CAN KILL.

If that's you, then there's other things to consider:

You'll need to do quite a lot of mugging up from text books.
Unfortunately the primary regs (BS7671 aka IEE 16th edition regs) are a
nightmare to understand & there is a busy cottage industry publishing
guides to the regs. Start off by checking the FAQ to this newsgroup
then post here if further queries.

Unfortunately SFAIK there are no design programs readily available
comparable to the widely available CH sizing programs. But you could
easily set up a spreadsheet to do the bulk of the work.

You'll need to invest in (or borrow) instruments - minimum you need is a
resistance/continuity tester which works on 500v (£50 up), but ideally
you need others, including an RCD tester, all in all £300 is easily
blown. A trap for the unwary is that to comply fully with BS7671 your
instruments require recalibration by an approved laboratory every 2
years.

Then once you've got the knowledge & the kit & done the job, if Part P
comes into force it's all useless to you.

If you do decide to go ahead, I'd say your worst problem is the
logistical one of getting your fuse/box consumer unit isolated so you
can work on the circuits. See if you can get a suppliers isolator
switch fitted - this goes immediately after the meter & might be free to
have fitted. If not see if they'll connect up your own isolator switch
between the meter & the fuse box without further ado.

A 1960's installation probably does need updating. It will have wired
fuses - modern domestic practice is now to use RCD consumer unit with
MCBs instead of fuses. An RCD often disconnects quite rapidly in the
event of a detected fault - if you're lucky keeping electric shock to a
minimum. An MCB (miniature circuit breaker) cuts out fairly sharply
(unlike a wired a fuse) on current overload & is resettable. In some
circumstances you can use cartridge fuses instead of an RCD/MCB, there
are pros & cons.

You need to check the bonding and earthing of the installation. Would
suggest you put this right first, before anything else. You need to
check bonding to the incoming water & gas supplies, plus the bathroom,
around any CH boiler, all CH & hot water pipes. Selecting the right
size of earth cable isn't always obvious. Post here if in doubt.

Your present cable if 60's vintage could be lead sheathed (dangerously
obsolete) or rubber covered FTE (obsolete & perhaps coming to the end of
its life) or PVC FTE. If PVC FTE you might be able to retain it, but
you need to check its spec against what you intend the cicuit to carry.

As for replacement cabling, be careful with PVC/FTE: it is pretty
ubiquitous in UK domestic wiring, but you have to use it with care. It
works best in an ambient 5 deg C to 25 deg C (ie typical UK temps).
Below 0 deg it gets brittle, above 30 deg C it needs derating. When it
carries current it heats up, but the operating temperature shouldn't
exceed 70 deg C (for std cable): your circuit design has to consider
this. If it gets too hot the conductors can work their way through the
insulation/sheath and short or become exposed. For the same reason you
have to careful bending it round corners. The IEE regs give various
current ratings depending on how the cable is mounted and what it
touches. Cables from different circuits also need keeping apart,
otherwise derating may have to be applied. It also has to be kept away
from hot pipes, sunlight plus ideally daylight, polystyrene; otherwise
it can rot. Contact with any sort of insulation such as rockwool, mica
means more derating. As for all cables it has internal resistance &
hence there is a voltage drop along the cable: ie you won't get the full
240v at the socket when a useful current is flowing. The regs set a
limit to allowable voltage drop which effectively sets a limit to the
length of a cable in a circuit.


>
>Thanks in advance for any insight.

HTH & gives you some insight into what's needed & the problems you might
encounter. Good luck
--
K

chris French

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Oct 4, 2002, 6:33:08 PM10/4/02
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In message <f9grpu4ls2h2vegm2...@hobgoblin.grok.co.uk>,
Chris Cowley <cco...@grok.co.uk> writes
>
Re old wiring.

>My current plan of action is to firstly
>figure out exactly what the current layout is

A good start.

> (there are three
>fuseboards with various bits of ageing bakelite and porcelain cack
>screwed to them) then, assuming the existing circuits are in reasonable
>order,

IME with a couple of older houses, pay particular attention to the
lighting circuits - these can often be older than the 13A sockets and
may well have old rubber or otherwise dodgy wiring. Look carefully, some
of ours had newer cables behind the switch plates, but old '30s rubber
stuff just behind the back boxes.


--
Chris French, Leeds

John Southern

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Oct 4, 2002, 7:41:27 PM10/4/02
to
What a pile a shite i gladly want to get in the trade and im 18 when i
left school i didnt get an apprenticeship. I passed the JTL test but i
did a full-time college course to gain my part 1 and 4 units of the
2351 for the JTL course.
I also did UNPAID work experience with local employers to get unit
evedence for my NVQ level 2 which i completed this year. Sadly the
college cancelled my part 2 course this january because only 3 of us
atended regulary including myself. I had been promised by a local
employer that hed take me on in april he didnt. I also resat the JTL
test for a second time and passed it. He told the careers centre that
im qualified for the job but there no way he would employ me 1 cheeky
fucker.
So no wonder there nobody going into the trade.

John.

Steve Taylor

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Oct 4, 2002, 8:17:31 PM10/4/02
to
K wrote:
> An MCB (miniature circuit breaker) cuts out fairly sharply
> (unlike a wired a fuse) on current overload & is resettable. In some
> circumstances you can use cartridge fuses instead of an RCD/MCB, there
> are pros & cons.

Fuses usually interrupt faster than MCBs, not the other way round.

>
> Your present cable if 60's vintage could be lead sheathed (dangerously
> obsolete) or rubber covered FTE (obsolete & perhaps coming to the end of
> its life) or PVC FTE. If PVC FTE you might be able to retain it, but
> you need to check its spec against what you intend the cicuit to carry.

Its VERY unlikely to be rubber or lead from the 60's

> above 30 deg C it needs derating. When it
> carries current it heats up, but the operating temperature shouldn't
> exceed 70 deg C (for std cable): your circuit design has to consider

> this. The regs set a


> limit to allowable voltage drop which effectively sets a limit to the
> length of a cable in a circuit.

--or you increase the conductor size....

Calculations are rarely needed in domestic installations, and derating
for conductor number and environment also rare. In industrial situations
of course things are a lot different. It really isn't terribly hard to
do a good job.

Steve

Dave Plowman

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Oct 4, 2002, 7:46:17 PM10/4/02
to
In article <KQGkWBA7...@tiltononthehill.demon.co.uk>,

K <K...@nospamplease.co.uk> wrote:
> Your present cable if 60's vintage could be lead sheathed

You jest, I presume?

--
* Go the extra mile. It makes your boss look like an incompetent slacker *

Chris Cowley

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Oct 5, 2002, 4:53:48 AM10/5/02
to
On Fri, 4 Oct 2002 23:36:43 +0100, K <K...@nospamplease.co.uk> wrote:

>Unfortunately SFAIK there are no design programs readily available
>comparable to the widely available CH sizing programs. But you could
>easily set up a spreadsheet to do the bulk of the work.

To be honest, I think a piece of A4 paper and a pencil will provide all
the planning capability I'll need. I live on the outskirts of London
were all my hard earned money has won me a house the size of a small
matchbox!

--
Chris Cowley

tony sayer

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Oct 5, 2002, 4:59:54 AM10/5/02
to
In article <711be9cb.02100...@posting.google.com>, John
Southern <johna...@btinternet.com> writes

>What a pile a shite i gladly want to get in the trade and im 18 when i
>left school i didnt get an apprenticeship. I passed the JTL test but i
>did a full-time college course to gain my part 1 and 4 units of the
>2351 for the JTL course.
>I also did UNPAID work experience with local employers to get unit
>evedence for my NVQ level 2 which i completed this year. Sadly the
>college cancelled my part 2 course this january because only 3 of us
>atended regulary including myself. I had been promised by a local
>employer that hed take me on in april he didnt. I also resat the JTL
>test for a second time and passed it. He told the careers centre that
>im qualified for the job but there no way he would employ me 1 cheeky
>fucker.
>So no wonder there nobody going into the trade.

Just to add a bit to this. My brother in law is a self-employed
bricklayer. He also has to do a bit of wood bashing and roof work etc.
However, as much as he would like to expand to do so would mean
employing people. To do this these days is bloody hard work. Not only
are there all the human factors involved with *managing* people there is
the pile of regulations, expense, and paperwork involved. So much so
that unless you're intending to employ a great number, so you can
justify the extra staff required to cope with the staff that you are
employing.

Least that's the biggest moan I hear from other small firms other than
things like cash flow etc...
--

Tony Sayer


Andrew Gabriel

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Oct 5, 2002, 5:18:23 AM10/5/02
to
In article <3d9e2cce$0$5808$fa0f...@lovejoy.zen.co.uk>,

Steve Taylor <st...@thetaylorfamily.org.uk> writes:
> K wrote:
>> An MCB (miniature circuit breaker) cuts out fairly sharply
>> (unlike a wired a fuse) on current overload & is resettable. In some
>> circumstances you can use cartridge fuses instead of an RCD/MCB, there
>> are pros & cons.
>
> Fuses usually interrupt faster than MCBs, not the other way round.

MCBs have two tripping elements - a thermal trip for overload
protection which is typically slower than a fuse, and a magnetic
trip for fault (short circuit) protection which is faster than
a fuse. The thermal element is the marked current rating on the
MCB, and the magnetic element is several times the marked current
rating - the type B, C, D indicates by how many times. It is the
ability to separately control these two elements which makes MCBs
powerful products for circuit protection. A fuse in comparision
has a single tripping element which has to compromise to meet the
requirements of overload protection and fault current protection.

>> Your present cable if 60's vintage could be lead sheathed (dangerously
>> obsolete) or rubber covered FTE (obsolete & perhaps coming to the end of
>> its life) or PVC FTE. If PVC FTE you might be able to retain it, but
>> you need to check its spec against what you intend the cicuit to carry.
>
> Its VERY unlikely to be rubber or lead from the 60's

PVC was in use certainly in the late 1950's - my parents' house was
built then and is all PVC. The lighting circuit includes CPC. At each
junction box, the CPC's do not enter it but are all brought around
the outside of the box and joined together. Of course, this predates
earth sleeving.

Rubber did continue into the early 1960's though. Except for its
tendancy to perish with ozone contact which is what lets it down,
it is superior to PVC - can run at higher temperatures and has higher
insulation resistance.

I haven't come across a lead sheathed rubber installation I can
accurately date, but I would suspect they were all well pre-1960.

Andrew Gabriel

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Oct 5, 2002, 5:52:59 AM10/5/02
to
In article <KQGkWBA7...@tiltononthehill.demon.co.uk>,

K <K...@nospamplease.co.uk> writes:
>
> If you do decide to go ahead, I'd say your worst problem is the
> logistical one of getting your fuse/box consumer unit isolated so you
> can work on the circuits. See if you can get a suppliers isolator
> switch fitted - this goes immediately after the meter & might be free to
> have fitted. If not see if they'll connect up your own isolator switch
> between the meter & the fuse box without further ado.

One way is to initially fit a new CU without removing any of the
old ones, and take its feed from a spare way (or disconnect an
unneeded circuit) in one of the old CU's. You'll want to use a
high current way, and ensure it's in good enough condition for
the supply load and you use a suitably rated cable to join in the
new CU. Avoid using high current appliances like electric showers
through this though. With such an arrangement, you can then
rewire over the next few weeks, putting the new circuits into
the new CU, and gradually disconnecting all the old circuits, just
leaving the old CUs in place. Finally, you can ask the electricity
company to transfer the tails to your new CU and disconnect the
old CUs.

Some people have reported being asked for test certificates when
this is done. I never have been. This might relate to how
professional or otherwise the workmanship looks around the new CU.

Dave Plowman

unread,
Oct 5, 2002, 9:54:42 AM10/5/02
to
In article <anmaov$lab$1...@new-usenet.uk.sun.com>,

Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
> I haven't come across a lead sheathed rubber installation I can
> accurately date, but I would suspect they were all well pre-1960.

I've quite a bit of amateur experience in old London houses and I'd say
any lead dates to well before WW2. Nor was it universal - one house I
re-wired had cotton covered stuff in wood conduit dating from the '20s -
although it had been subsequently re-wired in rubber. That's not to say it
wasn't available later, but I very much doubt it was used for new
installation work - unless some council etc had a bee in their bonnet.

My parent's house built new in the early '30s was wired in VIR singles,
neatly strapped to the side of the joists before the T&G flooring was
laid. This was in Aberdeen.

--
*Dance like nobody's watching.

Steve Taylor

unread,
Oct 5, 2002, 2:25:42 PM10/5/02
to
Andrew Gabriel wrote:
> MCBs have two tripping elements - a thermal trip for overload
> protection which is typically slower than a fuse, and a magnetic
> trip for fault (short circuit) protection which is faster than
> a fuse.

Hmmm, so what devices do we use for the fastest protection for say
semiconductors like triacs, Fuses or MCBs ?

Steve

chris French

unread,
Oct 5, 2002, 5:13:23 PM10/5/02
to
In message <4b806126ae...@argonet.co.uk>, Dave Plowman
<dave....@argonet.co.uk> writes

>In article <KQGkWBA7...@tiltononthehill.demon.co.uk>,
> K <K...@nospamplease.co.uk> wrote:
>> Your present cable if 60's vintage could be lead sheathed
>
>You jest, I presume?
>
There was a lead sheathed cable on the downstairs ring main in this
house on a circuit that was probably put in around the '60's. however I
doubt it was new then, probably reused cable - it was on one long run
from the fuse box, and I found no others.
--
Chris French, Leeds

Andrew Gabriel

unread,
Oct 5, 2002, 6:21:52 PM10/5/02
to
In article <3d9f2bd5$0$5808$fa0f...@lovejoy.zen.co.uk>,

There are very fast acting fuses (labelled FF) and there are
even faster semiconductor-based fuses. The former cost about
the same as a triac, and the latter cost more.
Just look on the triac as self-fusing ;-)

Dave Plowman

unread,
Oct 5, 2002, 6:08:57 PM10/5/02
to
In article <LPM26gCz...@chrisfrench.org>,

chris French <newsp...@chrisfrench.org> wrote:
> There was a lead sheathed cable on the downstairs ring main in this
> house on a circuit that was probably put in around the '60's. however I
> doubt it was new then, probably reused cable - it was on one long run
> from the fuse box, and I found no others.

Could be. My house had all the lighting wiring in lead when I bought it in
the early '70s. And it was all in very good condition - apart from the
exposed ends where the insulation had crumbled. It could have been re-used
by cutting back a few inches. So I'd not be surprised to find some still
usable even today.

--
*I finally got my head together, now my body is falling apart.

K

unread,
Oct 6, 2002, 5:23:20 PM10/6/02
to
In article Steve Taylor <st...@thetaylorfamily.org.uk> writes

>K wrote:
>> An MCB (miniature circuit breaker) cuts out fairly sharply
>> (unlike a wired a fuse) on current overload & is resettable. In some
>> circumstances you can use cartridge fuses instead of an RCD/MCB, there
>> are pros & cons.
>
>Fuses usually interrupt faster than MCBs, not the other way round.

cartridges, yes: wired fuses which seem to be at the heart of the
poster's grief: who knows? that's why circuits with wired fuses are
derated.

>
>>
>> Your present cable if 60's vintage could be lead sheathed (dangerously
>> obsolete) or rubber covered FTE (obsolete & perhaps coming to the end of
>> its life) or PVC FTE. If PVC FTE you might be able to retain it, but
>> you need to check its spec against what you intend the cicuit to carry.
>
>Its VERY unlikely to be rubber or lead from the 60's

I've certainly found lead sheathed cable attached to 60's vintage
switchgear. I don't know for sure when it was current - suspect it was
being installed in the mid- late 30's, but may not have survived 39/45.
Several villages in this area only got water & elec when American troops
installed it c. 1942-44 - from limited observations a long while ago,
round rubber cable was used. However lots of installations were
upgraded 1955-75 due to the MacMillan grants for bathrooms/hot
water/kitchens plus increased use of elec kit, etc & maybe the old
cables were just reused or simply reconnected to a new fusebox.

Rubber overlapped PVC for several years, so you'll find that too for the
same reasons.

BTW if you do find lead sheathed cable take great care, just handling it
can make the sheath live, because the sheath cracks (breaking the earth
link) & the internal rubber(?)/cotton(?) insulation has decayed. Makes
a nice spark, though. ;-)

>
>> above 30 deg C it needs derating. When it
>> carries current it heats up, but the operating temperature shouldn't
>> exceed 70 deg C (for std cable): your circuit design has to consider
>> this. The regs set a
>> limit to allowable voltage drop which effectively sets a limit to the
>> length of a cable in a circuit.
>
>--or you increase the conductor size....

that only puts off the evil day....there is still a (longer) length
limit

>
>Calculations are rarely needed in domestic installations,

maybe: if you're lucky someone has already done it for you

> and derating
>for conductor number and environment also rare.

yes, it is often possible to avoid this by careful choice of cable
routes etc, but you need to know the rules to achieve this. When
PVC/FTE first came out (mid 50's IIRC) it was used with gay abandon. It
wasn't long before it was discovered mice enjoyed chewing it (an anti-
rodent additive is added now). That was just the start of a chain of
cautions and no-nos. Eg, when PVC was introduced thermal insulation was
rare and it wasn't given much thought when cable planning, nowadays it
is common. its ill effects understood and it often has to be taken into
account (by avoiding runs near it whenever possible). Fresh PVC/FTE
cable has a slightly lively elastic feeling: prematurely aged by
overheating, it has a dead, leaden feel & makes my heart sink.


> In industrial situations
>of course things are a lot different. It really isn't terribly hard to
>do a good job.

not suggesting it is, but you get a much better job knowing the
characteristics of the material you're handling & making sure you don't
over push it. As with all engineering you generally get best results &
longest life by keeping things well within limits.


It's maybe especially important now for anyone setting out on a rewire
to be certain they've doing the job correctly, in view of the
government's plans re the Building Regs. We look to be moving into an
era when domestic DIY electrical work is done behind closed curtains.
It may not be possible to easily put errors right afterwards. So check
& double-checking plans is well advised.

& I'd repeat - treat PVC/FTE with respect.
--
K

K

unread,
Oct 6, 2002, 5:37:48 PM10/6/02
to
In article Chris Cowley <cco...@grok.co.uk> writes
>On Fri, 4 Oct 2002 23:36:43 +0100, K <K...@nospamplease.co.uk> wrote:
>
>>Unfortunately SFAIK there are no design programs readily available
>>comparable to the widely available CH sizing programs. But you could
>>easily set up a spreadsheet to do the bulk of the work.
>
>To be honest, I think a piece of A4 paper and a pencil will provide all
>the planning capability I'll need.

only a suggestion... I use a spreadsheet as project diary, for notes,
stock holding, as well as calculations of quantities, etc etc. very
convenient: keeps everything together & doesn't crumple... And once
you've set up a calculation you can easily copy it & modify it to suit a
second circuit or whatever. Wouldn't be without it

There is a useful cable calculator for PVC/FTE at

http://www.kevinboone.com/cablecalc.cgi

> I live on the outskirts of London
>were all my hard earned money has won me a house the size of a small
>matchbox!

nevertheless, 70m of cable (the usual limit of a ring) soon disappears
once it has been up and down a few walls.

>

--
K

Steve Taylor

unread,
Oct 6, 2002, 6:43:27 PM10/6/02
to
K wrote:
> cartridges, yes: wired fuses which seem to be at the heart of the
> poster's grief: who knows? that's why circuits with wired fuses are
> derated.
>

Not entirely sure of the rupture time for wired fuses, but the main
problem is likely to be their inability to interrupt high PFCs rather
than rupture time per sae.

>> BTW if you do find lead sheathed cable take great care, just handling it
> can make the sheath live, because the sheath cracks (breaking the earth
> link) & the internal rubber(?)/cotton(?) insulation has decayed. Makes
> a nice spark, though. ;-)

Doesn't it just !


> that only puts off the evil day....there is still a (longer) length
> limit

For 2.5 mm2 on a ring in a domestic installation, are you really going
to get 9.2 Volts of droop on a fully loaded ring ? 18mV/A/m

Steve

dave

unread,
Oct 6, 2002, 7:58:06 PM10/6/02
to

"K" <K...@nospamplease.co.uk> wrote in message
news:KQGkWBA7...@tiltononthehill.demon.co.uk...

Reading all the above, it brings a smile to my lips when I consider that I
have been granted the authority and licence to build and repair systems that
might have a couple of thousand Volts powering them and that they might
cause me burns in the process of using them.

For all this I just had to sit a simple City & Guilds exam.

In what?

I am a radio amateur.

Licensed to interfere with electricity. Will the intro of this farcical
regulation inhibit my hobby, I don't think so.

So why the hell should I stop wiring up extra sockets and lights just
because some one wants to regulate it? When this house next comes on the
market, I will probably be dead. How on earth can any one decide when a
wiring change came about?

> If that's you, then there's other things to consider:
>
> You'll need to do quite a lot of mugging up from text books.
> Unfortunately the primary regs (BS7671 aka IEE 16th edition regs) are a
> nightmare to understand & there is a busy cottage industry publishing
> guides to the regs.

I have worked with far tighter regs. than anything that the BS can come up
with while working on military jets. After you have done that sort of
paperwork, everything else is easy. :-)

Dave


Chris Cowley

unread,
Oct 7, 2002, 1:32:08 PM10/7/02
to
On Sun, 6 Oct 2002 22:37:48 +0100, K <K...@nospamplease.co.uk> wrote:

>There is a useful cable calculator for PVC/FTE at
>
>http://www.kevinboone.com/cablecalc.cgi

That might come in handy, I've bookmarked it. Thanks.

>nevertheless, 70m of cable (the usual limit of a ring) soon disappears
>once it has been up and down a few walls.

70m would encircle the entire perimeter of the house almost twice, so if
I exceed that limit there really is no hope for me at all!
--
Chris Cowley

Andy Wade

unread,
Oct 8, 2002, 5:41:59 PM10/8/02
to
Chris Cowley wrote in article
<erg3qu870obakpdfo...@hobgoblin.grok.co.uk>...

> On Sun, 6 Oct 2002 22:37:48 +0100, K <K...@nospamplease.co.uk> wrote:
>
> >There is a useful cable calculator for PVC/FTE at
> >http://www.kevinboone.com/cablecalc.cgi
>
> That might come in handy, I've bookmarked it. Thanks.

This appears to be out-of-date in the sense that it's unaware of the 'new
improved' current ratings for twin & earth - i.e. it's using Table 4D2A
ratings, not the newer Table 4D5A.

--
Andy

K

unread,
Oct 8, 2002, 5:49:21 PM10/8/02
to
In article <anqimd$snj$1...@paris.btinternet.com>, dave
<dave...@btopenworld.com> writes
<snip>

>
>Reading all the above, it brings a smile to my lips when I consider that I
>have been granted the authority and licence to build and repair systems that
>might have a couple of thousand Volts powering them and that they might
>cause me burns in the process of using them.
>
>For all this I just had to sit a simple City & Guilds exam.
>
>In what?
>
>I am a radio amateur.
>
>Licensed to interfere with electricity. Will the intro of this farcical
>regulation inhibit my hobby, I don't think so.

Perhaps you should reconsider.

BTW isn't the RSGB aware of the proposals? Hasn't it alerted its
members? [I see RSGB is not in the list of organizations consulted -
proposals are at

www.safety.odpm.gov.uk/bregs/consult/electric/index.htm]

>So why the hell should I stop wiring up extra sockets and lights just
>because some one wants to regulate it?

As a radio ham it will likely affect much more than your house wiring,
If any part of your station - and that includes all your aerial (up or
down) coax leads and any data wiring - is 'fixed to the building fabric'
then you will either have to employ a NICEIC/ECA member directly to
alter it, or employ such a contractor indirectly thru your local council
by making a building regs application (cost min £110).

> When this house next comes on the
>market, I will probably be dead. How on earth can any one decide when a
>wiring change came about?

regime proposed is similar to CORGI for gas - perhaps tighter as you can
modify your own gas under the CORGI system - & there's still quite a
black market of non-CORGI installers a decade after it started. So it
might not bite too hard for elec.

OTOH if someone gets a bee in the bonnet, perhaps after an accident,
maybe things could change suddenly. Panic shutdowns after a well
publicised incident seem to be getting more common. eg railways after
Potters Bar, checks on teachers after Soham etc..

And it is obviously in the interests of NICEIC/ECA to maintain their
closed shops. My understanding is that something similar pertains in Oz
where there are even tighter rules than Part P proposes. Any 'approved
contractor' will shop you...

Perhaps what's been happening with private cooking & supply of home
grown produce is a good guide. Both are now regarded as a threat to
Health & Safety.

Wherever you look every sort of DIY is being discouraged.


>
>> If that's you, then there's other things to consider:
>>
>> You'll need to do quite a lot of mugging up from text books.
>> Unfortunately the primary regs (BS7671 aka IEE 16th edition regs) are a
>> nightmare to understand & there is a busy cottage industry publishing
>> guides to the regs.
>
>I have worked with far tighter regs. than anything that the BS can come up
>with while working on military jets. After you have done that sort of
>paperwork,

umm.. you mean bs5750/isoi2000 paperwork systems?

> everything else is easy. :-)

16th IEE regs/BS7671 are styled on BS5750 & are paperwork & calibration
mad as per standard.

However it is easy to misunderstand the proposed new domestic electrical
regime. What will be required is compliance with the B.Regs Part P -
NOT BS7671 directly. Part P requires domestic wiring to be done by
approved contractors, who are...guess who? The approved contractor will
then have to comply with the detail of part P, IEE regs or whatever.
The difference is subtle & easily missed if you are in a hurry, but
nails DIY nicely even if you are electrically qualified.

One possible result will be that supply of cable, parts etc will dry up
except to approved firms. Ever tried to get a part (even a circuit
diagram) for Sony kit? - you'll find out it isn't safe for them to
supply you... Could get like that for elec bits & pieces.


--
K

raden

unread,
Oct 9, 2002, 3:25:59 PM10/9/02
to
In message <fkfhLHAh...@tiltononthehill.demon.co.uk>, K
<K...@nospamplease.co.uk> writes

>One possible result will be that supply of cable, parts etc will dry up
>except to approved firms. Ever tried to get a part (even a circuit
>diagram) for Sony kit? - you'll find out it isn't safe for them to
>supply you... Could get like that for elec bits & pieces.
>
>
I very much doubt it would get that bad - can you imagine RS, Maplins,
CPC, B&Q etc checking up on everyone who buys any gear from them ? to
say nothing of all the small electrical supply shops. There's nothing to
stop an individual from going into a CH supplier and buying bits. Even
if things were tightened up, there would always be a thriving black
market which would be impossible to police. Then there's always the
danger that people would re-use obsolete bits which would be even more
dangerous.

I think not.
--
raden

K

unread,
Oct 11, 2002, 3:29:59 PM10/11/02
to
In article raden <ra...@ntlworld.com> writes
>In message
><K...@nospamplease.co.uk> writes

>>One possible result will be that supply of cable, parts etc will dry up
>>except to approved firms. Ever tried to get a part (even a circuit
>>diagram) for Sony kit? - you'll find out it isn't safe for them to
>>supply you... Could get like that for elec bits & pieces.
>>
>>
>I very much doubt it would get that bad - can you imagine RS,

RS only knowingly supplies businesses: for similar reasons?

> Maplins,

they're not on the part P consultation circulation list, so who cares?
>
>CPC, B&Q

B&Q is


>etc checking up on everyone who buys any gear from them ?

look at the signs over the gas kit in B&Q - suggesting you don't even
think about asking for advice on gas kit & fittings

I notice that B&Q 'consolidated' their electrical stock a year or so
ago, prescience?

> to
>say nothing of all the small electrical supply shops.

none of those on the list, so who cares about them?

> There's nothing to
>stop an individual from going into a CH supplier and buying bits. Even
>if things were tightened up, there would always be a thriving black
>market which would be impossible to police.

what's the situation in Australia? I only hear at third hand, but the
vibes are not good.

Suppliers would be at risk of the latent threat that they could be held
to be 'aiding & abetting' by supplying parts for unapproved work. Just
one case of a large shed getting its fingers burnt in a well publicised
case could bring down the shutters on sales. They've plenty of other
lines.


>Then there's always the
>danger that people would re-use obsolete bits which would be even more
>dangerous.
>
>I think not.

bookmark your comments & look back in 10 years if part P comes in.

complacency is how we're tied in knots by gold plated regulations which
are then enforced rigidly & relentlessly.

--
K

raden

unread,
Oct 11, 2002, 4:11:48 PM10/11/02
to
In message <ODLVCGA3...@tiltononthehill.demon.co.uk>, K
<K...@nospamplease.co.uk> writes

>In article raden <ra...@ntlworld.com> writes
>>In message
>><K...@nospamplease.co.uk> writes
>
>>>One possible result will be that supply of cable, parts etc will dry up
>>>except to approved firms. Ever tried to get a part (even a circuit
>>>diagram) for Sony kit? - you'll find out it isn't safe for them to
>>>supply you... Could get like that for elec bits & pieces.
>>>
>>>
>>I very much doubt it would get that bad - can you imagine RS,
>
>RS only knowingly supplies businesses: for similar reasons?

I think that you'll find that anyone can now buy from their trade
counters. Anyway, for example,I am not an electrical contractor, but I
have an account with RS, so what's to stop me buying such goods ?

>
>> Maplins,
>
>they're not on the part P consultation circulation list, so who cares?
>>
>>CPC, B&Q
>
>B&Q is
>>etc checking up on everyone who buys any gear from them ?
>
>look at the signs over the gas kit in B&Q - suggesting you don't even
>think about asking for advice on gas kit & fittings

I don't buy gas fittings from such expensive outlets, so I haven't seen
them, but so what, if parts are on sale, they're on sale

>
>I notice that B&Q 'consolidated' their electrical stock a year or so
>ago, prescience?
>
>> to
>>say nothing of all the small electrical supply shops.
>
>none of those on the list, so who cares about them?

They sell cables and parts

>
>> There's nothing to
>>stop an individual from going into a CH supplier and buying bits. Even
>>if things were tightened up, there would always be a thriving black
>>market which would be impossible to police.
>
>what's the situation in Australia? I only hear at third hand, but the
>vibes are not good.

I have no idea what the situation is in Australia, what's the relevance
?

>
>Suppliers would be at risk of the latent threat that they could be held
>to be 'aiding & abetting' by supplying parts for unapproved work. Just
>one case of a large shed getting its fingers burnt in a well publicised
>case could bring down the shutters on sales. They've plenty of other
>lines.
>
>
>>Then there's always the
>>danger that people would re-use obsolete bits which would be even more
>>dangerous.
>>
>>I think not.
>
>bookmark your comments & look back in 10 years if part P comes in.

>
>complacency is how we're tied in knots by gold plated regulations which
>are then enforced rigidly & relentlessly.
>

--
raden

Dave Plowman

unread,
Oct 11, 2002, 4:17:52 PM10/11/02
to
In article <ODLVCGA3...@tiltononthehill.demon.co.uk>,

K <K...@nospamplease.co.uk> wrote:
> RS only knowingly supplies businesses: for similar reasons?

They'll supply anyone with a credit card via their website.

--
*I'm not being rude. You're just insignificant

Dave Plowman

unread,
Oct 12, 2002, 9:17:25 AM10/12/02
to
In article <ao93ea$mg1$1...@anubis.demon.co.uk>,

Huge <hu...@nospam.huge.org.uk> wrote:
> >RS only knowingly supplies businesses: for similar reasons?

> Untrue. RS sells retail through its "Electromail" business.

Is that still 'on the go'? Anyone with a credit card can buy via the RS
website and establish a customer number. After that you can phone RS
direct. I get the 'old' catalogues from a place I work at since I don't do
enough business with them to get them sent. Any place that has them would
be glad to give them away when the new ones come out, I'd guess.

--
*Is it true that cannibals don't eat clowns because they taste funny?

K

unread,
Oct 15, 2002, 5:29:34 PM10/15/02
to
In article raden <ra...@ntlworld.com> writes
<snip>

>>RS only knowingly supplies businesses: for similar reasons?
>
>I think that you'll find that anyone can now buy from their trade
>counters.

glad to hear the leopard has changed its spots: was as stated for
decades.

<snip>


>>> to
>>>say nothing of all the small electrical supply shops.
>>
>>none of those on the list, so who cares about them?
>
>They sell cables and parts

but out of those making the regs, who cares?

I don't often see it, but the Sunday Telegraph runs a full page every
week about new gold plated regs crippling one small business after
another. Big firms love the regs, it keeps the competition out of the
market.

<snip>


>>what's the situation in Australia? I only hear at third hand, but the
>>vibes are not good.
>
>I have no idea what the situation is in Australia, what's the relevance
>?

If you're trying to look into the future, it's maybe a good idea to look
out for similar examples. From what I gather the rules are even tighter
there than Part P proposes, so maybe a good model as to what will happen
here? - the social/political/cultural/legal scene is similar.

Maybe if some of the legislators thought thru what their proposals mean
in the real world a lot of people would be happier.

Can only repeat I view the future for all of us who undertake and enjoy
any sort of diy [of any sort] with considerable apprehension. The
technophobes are out in force.

In the particular case of Part P, I just cannot see how you can renovate
a house according to the rules. IMHE there's always an electric cable
that needs moving, isolating, etc whilst work goes on.
<snip>
--
K

Tim Mitchell

unread,
Oct 16, 2002, 12:17:32 PM10/16/02
to
In article <ao9d3u$omj$1...@anubis.demon.co.uk>, Huge
<hu...@nospam.huge.org.uk> writes
>In article <4b84464375...@argonet.co.uk>, Dave Plowman
><dave....@argonet.co.uk> writes:
>>In article <ao93ea$mg1$1...@anubis.demon.co.uk>,
>> Huge <hu...@nospam.huge.org.uk> wrote:
>>> >RS only knowingly supplies businesses: for similar reasons?
>>
>>> Untrue. RS sells retail through its "Electromail" business.
>>
>>Is that still 'on the go'?
>
>Dunno. Haven't bought anything from them for yonks because they're
>so expensive.
>
Doesn't exist any more, they will sell direct now.
--
Tim Mitchell
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