On 10/02/2014 17:14, Tim Watts wrote:
On Monday 10 February 2014 16:17 Harry Bloomfield wrote in uk.d-i-y:

Phil L explained :
paulfoel wrote:
Currently got wiring in the attic that runs a light. Originally just
a pull switch and bulb/holder but I've replaced with strip light.

However, what I want to do now is have plug socket up there. Is it
acceptable to run this wire into a double plug socket. (Then I can
put plug on end of wiring for light also and just plug this is
leaving me with one space socket).

Or leave well alone because its a light circuit?

It'll be on the lighting circuit.
Meaning that if you turn all the sockets off at the CU, this socket
will still be live.
It also means that if whatever you have plugged into it trips, the
whole lighting circuit will trip.

Whether this is 'acceptable' is up to you and no one can stop you,
but it's not really advisable....if it's only going to be used for
occasional use, it's probably easier just to run an extension reel up
there when required.

I agree, you have to consider that someone may come along and assume
it is safe to plug a 3Kw heater in there. Much safer would be to run a
spur off the upstairs ring, to a twin 13 amp socket, then use one
outlet for the light, via a suitably small fuse in the plug, leaving
you one outlet for your angle grinder, wander light, or what ever.

There is almost always an easy cable route from the 1st floor
floor-level, upto the loft space - airing cupboard etc..

If you then somehow manage to trip that, you will still have some
working light on the floor below.


well, in the worst case, it will take out the protective device (fuse) -
which will be annoying, but not actually dangerous...

A 5A fuse in a spur probably won't blow before the 6A breaker in the CU
anyway so its not actually going to improve protection.
It may make the circuit easier to understand.

dennis@home wrote:

A 5A fuse in a spur probably won't blow before the 6A breaker in the
CU anyway so its not actually going to improve protection.

Thank you.

--

Adam

On Mon, 10 Feb 2014 19:27:09 +0000, "dennis@home"
wrote:

On 10/02/2014 17:14, Tim Watts wrote:
On Monday 10 February 2014 16:17 Harry Bloomfield wrote in uk.d-i-y:

Phil L explained :
paulfoel wrote:
Currently got wiring in the attic that runs a light. Originally just
a pull switch and bulb/holder but I've replaced with strip light.

However, what I want to do now is have plug socket up there. Is it
acceptable to run this wire into a double plug socket. (Then I can
put plug on end of wiring for light also and just plug this is
leaving me with one space socket).

Or leave well alone because its a light circuit?

It'll be on the lighting circuit.
Meaning that if you turn all the sockets off at the CU, this socket
will still be live.
It also means that if whatever you have plugged into it trips, the
whole lighting circuit will trip.

Whether this is 'acceptable' is up to you and no one can stop you,
but it's not really advisable....if it's only going to be used for
occasional use, it's probably easier just to run an extension reel up
there when required.

I agree, you have to consider that someone may come along and assume
it is safe to plug a 3Kw heater in there. Much safer would be to run a
spur off the upstairs ring, to a twin 13 amp socket, then use one
outlet for the light, via a suitably small fuse in the plug, leaving
you one outlet for your angle grinder, wander light, or what ever.

There is almost always an easy cable route from the 1st floor
floor-level, upto the loft space - airing cupboard etc..

If you then somehow manage to trip that, you will still have some
working light on the floor below.


well, in the worst case, it will take out the protective device (fuse) -
which will be annoying, but not actually dangerous...

A 5A fuse in a spur probably won't blow before the 6A breaker in the CU
anyway so its not actually going to improve protection.
It may make the circuit easier to understand.


Electrically speaking, you can wire a 13A socket straight off the
lighting wiring without compromising safety, provided the lighting
circuit remains fused at its 6 amp maximum limit.

If you're fitting a 13A socket in the loft or attic, it's usually for
the purposes of providing power to something like a masthead amp or TV
aerial distribution amp both of which would be more than amply served
by a half amp fuse[1] which minimises the risk of a house fire should
a fault develop on the (now fused) 13A socket spur.

Of course, there still remains the risk of a fire from a fault in the
amplifier kit itself but, provided it has been designed to the
mandatory safety requirements for such 'domestic appliances' this
aught to eliminate such risk. The only problem is that, unlike a radio
or hairdrier, it is operating 'out of sight' of any human supervision.

I'd be inclined to mount such devices on a metal shelf with heat
resistant deflectors (steel sheeting) to stop any flamage from
reaching any flamable construction materials and, for good measure,
install a loud smoke detector above, but to one side of said kit,
ideally with a repeater just outside of the loft hatchway or attic
doorway.

In my case, that last bit of paranoia has remained merely an idle
inclination to this day (although I might try the smoke alarm idea).

[1] If you needed to provide power for powertools, you'd just plug in
a suitable mains lead extension into one of your regular 13A sockets
unless you were planning on turning your attic into a workshop (in
which case we wouldn't be discussing the use of a lighting circuit
feed for a 13A socket now, would we?).

Fitting a 13A fused box in the spur feed to the 13A socket allows you
to fit a half or 1 amp fuse which will be more than ample for the
socket's intended purpose yet reduce the risk of a fault on the spur
from blacking out that lighting circuit. It's just a matter of "Good
Practice" and common sense to splash out on such a 'luxury item'.

The same applies to fusing up 30A ring main circuits with lower rated
fuses when appropriate. My top floor ring main currently has a 15A
fuse link fitted because the only loads are my son's "HiFi" and
widescreen TV and computer stuff with no 2kW electric fan heaters in
sight.

The 15A fuse link has never blown in the past 7 or 8 years since I
downgraded the circuit to a "15A Ring Main". The risk of a fire in the
ring main circuit, though slight enough to be deemed acceptable
according to the regulations is now somewhat safer again.

I like the principle that you can replace a large fuse link in an
existing fuse carrier with smaller rated fuse links (Wylex CU) since
it makes it very simple to downgrade the ciruit capacity on an as
needed basis without compromising safety (in this case, boosting
safety), since it's a trivial exercise to refit the original larger
fuse should the smaller one blow due to unanticipated overload.
--
Regards, J B Good

On Tuesday, February 11, 2014 8:32:39 PM UTC, Johny B Good wrote:


If you're fitting a 13A socket in the loft or attic, it's usually for
the purposes of providing power to something like a masthead amp or TV
aerial distribution amp both of which would be more than amply served
by a half amp fuse[1] which minimises the risk of a house fire should
a fault develop on the (now fused) 13A socket spur.

2A and below suffer much more frequent failure, I expect one of the reasons for the choice of 3A fuses in the 40s.

Of course, there still remains the risk of a fire from a fault in the
amplifier kit itself but, provided it has been designed to the
mandatory safety requirements for such 'domestic appliances' this
aught to eliminate such risk.

no

The only problem is that, unlike a radio
or hairdrier, it is operating 'out of sight' of any human supervision.
I'd be inclined to mount such devices on a metal shelf with heat
resistant deflectors (steel sheeting) to stop any flamage from
reaching any flamable construction materials and, for good measure,
install a loud smoke detector above, but to one side of said kit,
ideally with a repeater just outside of the loft hatchway or attic
doorway.

Biscuit tins are relatively easy to apply. Snip & bend back the 3 tabs for each hole. They restrict airflow, so a signifcant fire size cant happen. Things can get hot, but fire heat wont add to it significantly.


[1] If you needed to provide power for powertools, you'd just plug in
a suitable mains lead extension into one of your regular 13A sockets
unless you were planning on turning your attic into a workshop (in
which case we wouldn't be discussing the use of a lighting circuit
feed for a 13A socket now, would we?).

I've seen whole flats here running on a 5A feed. A pain, but workable. In eastern europe its standard practice to have an 8A feed to flats.


NT

On 2014-02-11, wrote:

On Tuesday, February 11, 2014 8:32:39 PM UTC, Johny B Good wrote:


If you're fitting a 13A socket in the loft or attic, it's usually for
the purposes of providing power to something like a masthead amp or TV
aerial distribution amp both of which would be more than amply served
by a half amp fuse[1] which minimises the risk of a house fire should
a fault develop on the (now fused) 13A socket spur.

2A and below suffer much more frequent failure, I expect one of the reasons for the choice of 3A fuses in the 40s.

Has fuse manufacturing not improved in the past 70 years?

On Thursday, February 13, 2014 4:03:39 PM UTC, Adam Funk wrote:
On 2014-02-11, wrote:
On Tuesday, February 11, 2014 8:32:39 PM UTC, Johny B Good wrote:

If you're fitting a 13A socket in the loft or attic, it's usually for
the purposes of providing power to something like a masthead amp or TV
aerial distribution amp both of which would be more than amply served
by a half amp fuse[1] which minimises the risk of a house fire should
a fault develop on the (now fused) 13A socket spur.

2A and below suffer much more frequent failure, I expect one of the reasons for the choice of 3A fuses in the 40s.

Has fuse manufacturing not improved in the past 70 years?

AFAIK fuse wire is still the same material (tinned copper) it was 100 years ago. Its drawn differently, but afaik the result is the same. 3/13A cartridges have only changed in very minor details since their design in the 40s. BICBW.


NT

In message , Johny B Good
writes

I like the principle that you can replace a large fuse link in an
existing fuse carrier with smaller rated fuse links (Wylex CU) since
it makes it very simple to downgrade the ciruit capacity on an as
needed basis without compromising safety (in this case, boosting
safety), since it's a trivial exercise to refit the original larger
fuse should the smaller one blow due to unanticipated overload.

Of course the opposite is also easy....
--
Chris French

On Thu, 13 Feb 2014 15:02:32 +0000, chris French
wrote:

In message , Johny B Good
writes

I like the principle that you can replace a large fuse link in an
existing fuse carrier with smaller rated fuse links (Wylex CU) since
it makes it very simple to downgrade the ciruit capacity on an as
needed basis without compromising safety (in this case, boosting
safety), since it's a trivial exercise to refit the original larger
fuse should the smaller one blow due to unanticipated overload.

Of course the opposite is also easy....

If you mean fitting a larger fuse carrier in place of the smaller
fuse carrier (e.g. fitting a 15A fuse carrier into a 5A fuse bridge)
it's actually impossible without the assistance of a "Birmingham
Screwdriver".

Perhaps I'm a little out of the ordinary in keeping a set of
correctly wired fuse carriers spare to facilitate fuse replacement.
Perhaps I'm also a little unusual in only re-wiring a blown fuse with
the correct fusewire.

The practice of miswiring fuses with the wrong fuse wire seems to be
one only followed by those aiming to earn a "Darwin Award". The fuse
carriers are clearly marked with their fuse rating amperage and the
fusewire card clearly identifies each wrap of fusewire and it's not
exactly 'Rocket Science' to figure how to rewire a Wylex fuse carrier.

The fact that Niglon cards of replacement fusewire were readily
available from almost any hardware store or chandlers does suggest
that this was a job that was deemed to be within the competence of the
typical literate householder of the day.
--
Regards, J B Good

In article , Johny B Good
scribeth thus
On Thu, 13 Feb 2014 15:02:32 +0000, chris French
wrote:

In message , Johny B Good
writes

I like the principle that you can replace a large fuse link in an
existing fuse carrier with smaller rated fuse links (Wylex CU) since
it makes it very simple to downgrade the ciruit capacity on an as
needed basis without compromising safety (in this case, boosting
safety), since it's a trivial exercise to refit the original larger
fuse should the smaller one blow due to unanticipated overload.

Of course the opposite is also easy....

If you mean fitting a larger fuse carrier in place of the smaller
fuse carrier (e.g. fitting a 15A fuse carrier into a 5A fuse bridge)
it's actually impossible without the assistance of a "Birmingham
Screwdriver".

Perhaps I'm a little out of the ordinary in keeping a set of
correctly wired fuse carriers spare to facilitate fuse replacement.
Perhaps I'm also a little unusual in only re-wiring a blown fuse with
the correct fusewire.

The practice of miswiring fuses with the wrong fuse wire seems to be
one only followed by those aiming to earn a "Darwin Award". The fuse
carriers are clearly marked with their fuse rating amperage and the
fusewire card clearly identifies each wrap of fusewire and it's not
exactly 'Rocket Science' to figure how to rewire a Wylex fuse carrier.

The fact that Niglon cards of replacement fusewire were readily
available from almost any hardware store or chandlers does suggest
that this was a job that was deemed to be within the competence of the
typical literate householder of the day.


Theres people I know who'd have to get a man in to "change a damm light
bulb";!...


--
Tony Sayer

In article ,
tony sayer wrote:
In article , Johny B Good
scribeth thus
On Thu, 13 Feb 2014 15:02:32 +0000, chris French
wrote:

In message , Johny B Good
writes

I like the principle that you can replace a large fuse link in an
existing fuse carrier with smaller rated fuse links (Wylex CU) since
it makes it very simple to downgrade the ciruit capacity on an as
needed basis without compromising safety (in this case, boosting
safety), since it's a trivial exercise to refit the original larger
fuse should the smaller one blow due to unanticipated overload.

Of course the opposite is also easy....

If you mean fitting a larger fuse carrier in place of the smaller
fuse carrier (e.g. fitting a 15A fuse carrier into a 5A fuse bridge)
it's actually impossible without the assistance of a "Birmingham
Screwdriver".

Perhaps I'm a little out of the ordinary in keeping a set of
correctly wired fuse carriers spare to facilitate fuse replacement.
Perhaps I'm also a little unusual in only re-wiring a blown fuse with
the correct fusewire.

The practice of miswiring fuses with the wrong fuse wire seems to be
one only followed by those aiming to earn a "Darwin Award". The fuse
carriers are clearly marked with their fuse rating amperage and the
fusewire card clearly identifies each wrap of fusewire and it's not
exactly 'Rocket Science' to figure how to rewire a Wylex fuse carrier.

The fact that Niglon cards of replacement fusewire were readily
available from almost any hardware store or chandlers does suggest
that this was a job that was deemed to be within the competence of the
typical literate householder of the day.


Theres people I know who'd have to get a man in to "change a damm light
bulb";!...

A friend had a local handyman in to hang her Christmas lights since her
husband was still recovering from a hip operation.

--
From KT24

Using a RISC OS computer running v5.18

In article ,
Johny B Good wrote:
On Thu, 13 Feb 2014 15:02:32 +0000, chris French
wrote:

In message , Johny B Good
writes

I like the principle that you can replace a large fuse link in an
existing fuse carrier with smaller rated fuse links (Wylex CU) since
it makes it very simple to downgrade the ciruit capacity on an as
needed basis without compromising safety (in this case, boosting
safety), since it's a trivial exercise to refit the original larger
fuse should the smaller one blow due to unanticipated overload.

Of course the opposite is also easy....

If you mean fitting a larger fuse carrier in place of the smaller
fuse carrier (e.g. fitting a 15A fuse carrier into a 5A fuse bridge)
it's actually impossible without the assistance of a "Birmingham
Screwdriver".

Perhaps I'm a little out of the ordinary in keeping a set of
correctly wired fuse carriers spare to facilitate fuse replacement.
Perhaps I'm also a little unusual in only re-wiring a blown fuse with
the correct fusewire.

what's wrong with a 6" nail?

--
From KT24

Using a RISC OS computer running v5.18

In message , charles
writes
In article ,
Johny B Good wrote:
On Thu, 13 Feb 2014 15:02:32 +0000, chris French
wrote:

In message , Johny B Good
writes

I like the principle that you can replace a large fuse link in an
existing fuse carrier with smaller rated fuse links (Wylex CU) since
it makes it very simple to downgrade the ciruit capacity on an as
needed basis without compromising safety (in this case, boosting
safety), since it's a trivial exercise to refit the original larger
fuse should the smaller one blow due to unanticipated overload.

Of course the opposite is also easy....

If you mean fitting a larger fuse carrier in place of the smaller
fuse carrier (e.g. fitting a 15A fuse carrier into a 5A fuse bridge)
it's actually impossible without the assistance of a "Birmingham
Screwdriver".

Perhaps I'm a little out of the ordinary in keeping a set of
correctly wired fuse carriers spare to facilitate fuse replacement.
Perhaps I'm also a little unusual in only re-wiring a blown fuse with
the correct fusewire.

what's wrong with a 6" nail?

Back in the good old days a brass volume control shaft was a good
replacement for any value of fuse in a 13A plug. Never seen one blow.


--
Bill

In article ,
Bill wrote:
In message , charles
writes
In article ,
Johny B Good wrote:
On Thu, 13 Feb 2014 15:02:32 +0000, chris French
wrote:

In message , Johny B Good
writes

I like the principle that you can replace a large fuse link in an
existing fuse carrier with smaller rated fuse links (Wylex CU) since
it makes it very simple to downgrade the ciruit capacity on an as
needed basis without compromising safety (in this case, boosting
safety), since it's a trivial exercise to refit the original larger
fuse should the smaller one blow due to unanticipated overload.

Of course the opposite is also easy....

If you mean fitting a larger fuse carrier in place of the smaller
fuse carrier (e.g. fitting a 15A fuse carrier into a 5A fuse bridge)
it's actually impossible without the assistance of a "Birmingham
Screwdriver".

Perhaps I'm a little out of the ordinary in keeping a set of
correctly wired fuse carriers spare to facilitate fuse replacement.
Perhaps I'm also a little unusual in only re-wiring a blown fuse with
the correct fusewire.

what's wrong with a 6" nail?

Back in the good old days a brass volume control shaft was a good
replacement for any value of fuse in a 13A plug. Never seen one blow.

knew them well.

--
From KT24

Using a RISC OS computer running v5.18