Just a quick question to any electrical experts in here.

I want to put a plug socket in my loft, but i'm not sure where to take
it from, as there are no ring main power cables up there, only
lighting cables.
There is however, the enormous cable for my shower!, (10mm T&E I
think) which i'm sure could easily supply a single power socket. The
thing is, I can't seem to find a junction box to take this size cable
(well, not at B&Q, Wickes etc.), although I haven't tried a merchants
yet. Also, is this the right way to join to a cable this size, or
indeed, is this meant to be done at all (i've been told, not by an
expert mind, that you should never run anything else from a shower
cable, only the shower).
The shower is 9.5 kW, so the 10mm cable must have plenty left for a
power circuit, i'd have thought). I guess the alternative is to take a
spur from a socket in one of the bedrooms etc., but I don't want to
upset any decorating. I just want to locate a suitable source already
i the loft.

Perhaps i'm going about this all the wrong way, if so can antone
suggest anything else (from the available cables in th loft).

I'm aware of the changes to wiring regulations recently, but not sure
if this applies to what I want to do, if so then I'll get someone
qualified to do it.

Graham

graham wrote:
Just a quick question to any electrical experts in here.
I want to put a plug socket in my loft, but i'm not sure where to take
it from, as there are no ring main power cables up there, only
lighting cables.

No. Lighitng circuit rated at 6A. 13A socket rated at 13A. Also, if your
house has TT earthing, the lighting circuit might not be protected with
a 30mA RCD, which is required for sockets on a TT installation.

There is however, the enormous cable for my shower!, (10mm T&E I
think) which i'm sure could easily supply a single power socket. The
thing is, I can't seem to find a junction box to take this size cable
(well, not at B&Q, Wickes etc.), although I haven't tried a merchants
yet. Also, is this the right way to join to a cable this size, or
indeed, is this meant to be done at all (i've been told, not by an
expert mind, that you should never run anything else from a shower
cable, only the shower).

That is correct.

The shower is 9.5 kW, so the 10mm cable must have plenty left for a
power circuit, i'd have thought).

Not much. A 9.5kW shower is 39.5A; 10mm cable is rated 43A in thermal
insulation, which may be the case in the loft. That is *without*
correction for ambient temperature, which may well require a derating
factor in a loft, of perhaps 0.71. So your 10mm cable may actually be
under-rated for the shower.

I guess the alternative is to take a
spur from a socket in one of the bedrooms etc., but I don't want to
upset any decorating. I just want to locate a suitable source already
i the loft.

Don't you have any fitted cupboards you can take a cable up inside?
Provided it is not in an area subject to physical damage and is visible,
surface clipped cable is perfectly acceptable in a domestic
installation. Take it neatly along a skirting board and up a doorframe,
then through a neat hole drilled in any cornice, and leave some slack at
each end, so that the cable can be concealed when the room is next
decorated. Even taking it up the side of a window can mean it is
concealed by floor-to-ceiling curtains in some cases.

Owain

On Tue, 31 May 2005 16:49:50 GMT, graham
wrote:

Just a quick question to any electrical experts in here.

I want to put a plug socket in my loft, but i'm not sure where to take
it from, as there are no ring main power cables up there, only
lighting cables.
There is however, the enormous cable for my shower!, (10mm T&E I
think) which i'm sure could easily supply a single power socket. The
thing is, I can't seem to find a junction box to take this size cable
(well, not at B&Q, Wickes etc.), although I haven't tried a merchants
yet. Also, is this the right way to join to a cable this size, or
indeed, is this meant to be done at all (i've been told, not by an
expert mind, that you should never run anything else from a shower
cable, only the shower).
The shower is 9.5 kW, so the 10mm cable must have plenty left for a
power circuit, i'd have thought). I guess the alternative is to take a
spur from a socket in one of the bedrooms etc., but I don't want to
upset any decorating. I just want to locate a suitable source already
i the loft.

Perhaps i'm going about this all the wrong way, if so can antone
suggest anything else (from the available cables in th loft).

I'm aware of the changes to wiring regulations recently, but not sure
if this applies to what I want to do, if so then I'll get someone
qualified to do it.

Graham

Personally I wouldn't interfere with the shower feed in any way. You
don't happen to have a socket in an airing cupboard do you ? They
used to be a common feature.

Andy

On Tue, 31 May 2005 16:49:50 GMT, graham
strung together this:

Just a quick question to any electrical experts in here.

Er.....

I want to put a plug socket in my loft, but i'm not sure where to take
it from, as there are no ring main power cables up there, only
lighting cables.
There is however, the enormous cable for my shower!,

No, no and thrice no. Don't do it, full stop.

Also, is this the right way to join to a cable this size, or
indeed, is this meant to be done at all (i've been told, not by an
expert mind, that you should never run anything else from a shower
cable, only the shower).

Correct, don't do it.

The shower is 9.5 kW, so the 10mm cable must have plenty left for a
power circuit, i'd have thought).

Stop thinking, it's ot going to do any of us any good. "Assumption is
the mother of all **** ups".

I guess the alternative is to take a
spur from a socket in one of the bedrooms etc., but I don't want to
upset any decorating. I just want to locate a suitable source already
i the loft.

Not so much an alternative, as the only correct way to do it.
You must have a cupboard or wardrobe somewhere with a socket behind it
or backing onto it. You can easily drill through from a suitable
socket, up through a cupboard and into the loft to a socket. If not,
just whack a length of trunking up the wall as a temporary job and
sink it in the wall next time you decorate that wall.
--

SJW
Please reply to group or use 'usenet' in email subject

In article ,
Owain writes:
graham wrote:
Just a quick question to any electrical experts in here.
I want to put a plug socket in my loft, but i'm not sure where to take
it from, as there are no ring main power cables up there, only
lighting cables.

No. Lighitng circuit rated at 6A. 13A socket rated at 13A. Also, if your
house has TT earthing, the lighting circuit might not be protected with
a 30mA RCD, which is required for sockets on a TT installation.

Minor nit, but the RCD for protecting all socket outlets
in a TT system does not need to be limited to 30mA (it
isn't there to protect against electrocution).

--
Andrew Gabriel

I'd run it from a lighting cable. What is the socket going to be used for? and how often?

"wig" wrote in message
...
I'm aware of the changes to wiring regulations recently, but not sure
if this applies to what I want to do, if so then I'll get someone
qualified to do it.

Graham

I'd run it from a lighting cable. What is the socket going to be used
for? and how often?


Regulations wise, if it comes from the bathroom, I believe Part P covers it
and it must be installed by an electrician. However, I don't believe any
electrician would take it from your shower feed. Would it be difficult just
to take a channel up a wall and into the loft from a wall socket and then
plaster/paint/paper over it?

AFAIK, you shouldn't use the lighting circuit at all, as even if you don't,
a future person could attach something of high load and cause a fire.

I'm no electrician though so I'm sure there'll be a flood of answers from
those who are soon enough



a

al wrote:

AFAIK, you shouldn't use the lighting circuit at all, as even if you don't,
a future person could attach something of high load and cause a fire.

But any load higher than 5 or 6 amps would trip/blow the lighting circuit's MCB or
fuse, so I can't see how it would be dangerous ? That's not to say it's
reg-compliant ! The only safety issue (ignoring the regs etc) would be the
possible lack of RCD protection.

--
Mark
Please replace invalid and invalid with gmx and net to reply

No. Lighitng circuit rated at 6A. 13A socket rated at 13A. Also, if
your house has TT earthing, the lighting circuit might not be
protected with a 30mA RCD, which is required for sockets on a TT
installation.

Minor nit, but the RCD for protecting all socket outlets
in a TT system does not need to be limited to 30mA (it
isn't there to protect against electrocution).

Minor nit v2.0. The lighting circuit should be protected by an RCD in a TT
earthed house anyway.

Christian.

On Wed, 01 Jun 2005 09:04:58 +0100, Mark Carver wrote:

al wrote:

AFAIK, you shouldn't use the lighting circuit at all, as even if you don't,
a future person could attach something of high load and cause a fire.

But any load higher than 5 or 6 amps would trip/blow the lighting circuit's MCB or
fuse, so I can't see how it would be dangerous ? That's not to say it's
reg-compliant ! The only safety issue (ignoring the regs etc) would be the
possible lack of RCD protection.

Assuming someone has not uprated the fuse/mcb !!!

Dave

Mark Carver wrote:
al wrote:

AFAIK, you shouldn't use the lighting circuit at all, as even if you
don't, a future person could attach something of high load and cause a
fire.


But any load higher than 5 or 6 amps would trip/blow the lighting
circuit's MCB or fuse, so I can't see how it would be dangerous ? That's
not to say it's reg-compliant ! The only safety issue (ignoring the
regs etc) would be the possible lack of RCD protection.


Maybe.. But not straight away, they take time to trip and even when they
do the chances are the cable has heated up considerably. So if a future
home owner does this on a regular basis he may damage the cable by
heating it too much. Eventually you'd get a short which may not
instantly blow a fuse (say if it's been replaced with one of the wrong
rating to stop it blowing!) and then you get your fire.

Another reason I think this may be a bad idea is if you get a novice
DIY-er who wishes to say install a double socket, he goes to his CU and
switches off the ring marked 'upstairs plugs' or whatever. So when he
thinks it's dead... It may not be. Same may go for a shower spur too.

Of course this is all hear-say by me who's electrical knowledge is
non-professional.

--
Regards,
Aaron.

Aaron wrote:
Mark Carver wrote:

al wrote:

AFAIK, you shouldn't use the lighting circuit at all, as even if
you don't, a future person could attach something of high load and
cause a fire.



But any load higher than 5 or 6 amps would trip/blow the lighting
circuit's MCB or fuse, so I can't see how it would be dangerous ?
That's not to say it's reg-compliant ! The only safety issue
(ignoring the regs etc) would be the possible lack of RCD protection.


Maybe.. But not straight away, they take time to trip and even when they
do the chances are the cable has heated up considerably. So if a future
home owner does this on a regular basis he may damage the cable by
heating it too much. Eventually you'd get a short which may not
instantly blow a fuse (say if it's been replaced with one of the wrong
rating to stop it blowing!) and then you get your fire.

Another reason I think this may be a bad idea is if you get a novice
DIY-er who wishes to say install a double socket, he goes to his CU and
switches off the ring marked 'upstairs plugs' or whatever. So when he
thinks it's dead... It may not be. Same may go for a shower spur too.

Of course this is all hear-say by me who's electrical knowledge is
non-professional.

Yes, I'm not advocating leaving such an arrangement for any future house owner,
such a thing should obviously be removed if you sell the house, but for one's own
use, under your own control etc, I see nothing wrong.

Of course should your house burn down due to a totally unrelated cause, and the
socket connected to the lighting circuit is found by investigators, it might well
invalidate your insurance claim. :-)


--
Mark
Please replace invalid and invalid with gmx and net to reply

"dave stanton" wrote in message
news
On Wed, 01 Jun 2005 09:04:58 +0100, Mark Carver wrote:

al wrote:

AFAIK, you shouldn't use the lighting circuit at all, as even if you
don't,
a future person could attach something of high load and cause a fire.

But any load higher than 5 or 6 amps would trip/blow the lighting
circuit's MCB or
fuse, so I can't see how it would be dangerous ? That's not to say it's
reg-compliant ! The only safety issue (ignoring the regs etc) would be
the
possible lack of RCD protection.

Run it through a fused connection unit with a 5amp fuse, thus there are 2
fuses protecting the socket. yes some could uprate both fuses - but then
again someone could re wire the socket completely.

O
Run it through a fused connection unit with a 5amp fuse, thus there are 2
fuses protecting the socket. yes some could uprate both fuses - but then
again someone could re wire the socket completely.

Still not good practice though.

Dave

"Mark Carver" wrote in message
...
But any load higher than 5 or 6 amps would trip/blow the lighting
circuit's MCB or fuse, so I can't see how it would be dangerous ? That's
not to say it's reg-compliant ! The only safety issue (ignoring the regs
etc) would be the possible lack of RCD protection.

That's true enough. Still not the best thing to do. If a wiring inspection
were done when you go to sell, I'm sure it would be pointed out as a
"fault".




a

al wrote:

AFAIK, you shouldn't use the lighting circuit at all, as even if you don't,
a future person could attach something of high load and cause a fire.

Strangely.... When we re-wired our on-going project, there was a 2KW
electric fan in the bathroom wired from the lighting circuit.

Only initially realised this when all the downstairs (Bedroom/bathroom)
lights were on and I flicked the heater on full.

When we had an electrician round to quote on re-wiring I mentioned it
and he said it's not uncommon and he's even done it himself on occasions!

He didn't say how long ago mind.

wig wrote:

I'd run it from a lighting cable. What is the socket going to be used
for? and how often?

Just Say No.

Take a feed from an appropriate circuit. An appropriate circuit is one
wot's got other sockits onit. Not the shower, not the light. Either one
of those risks overloading the cable - and for those who believe that an
MCB rated at 6A will instantly blow if you pull 6.01A, 6.1A, or 7A - no,
it won't. It'll let 9-10A pass for 15-20 minutes at least. *If* you're
lucky, the lighting cable's 1.5mmsq and can dissipate heat easily, so
drawing 9A (full lighting load + 1kw fan-heater warming you in the loft)
won't matter at all. If it's wired in the more normal (and cheaper, so
bound to be used in any mass-built house) 1mmsq, and passes through good
thick thermal insulation for any substantial part of its run, it'll warm
up good and proper. No, it won't burst into flames; yes, the PVC
insulation *will* soften, and anywhere there's a bit of pressure on it
or a bend in the cable, the softened insulation *will* flow slowly away,
leaving bare conductors if you're unlucky.

How are you for black cats and paired magpies?

Similar thought tells you why putting a 13A socket on your shower cable
is a no-no. Again, the cable and MCB/fuse have been sized for the shower
you have (or for the shower that was initially installed; possibly
replaced later by a higher-current model). If the shower's a dinky
little 7.5kW job (draws 31A), and it's wired in 10mmsq because that's
what the sparks had on the van that day, and it takes a thermally-kind
route - no practical problem. (Still a Regs violation, of course.) If
the shower's a 9.6kW job (40A), run on a 6mmsq cable which was OK for
the previous one which a handyperson's replaced with the new whizzy
model, running through thermal insulation so it's already running at or
over the sustained-temp limit of 70 degrees, with a 40A or 45A MCB
fitted by the same handydroid to Uprate the shower, and you fit a 13A
socket on it, wh'appen when it's *really* cold oop in t'loft and you
wind the fanheater up to 3kW, while someone else takes a shower? The
current's now up to 52A. Your 40A MCB doesn't mind, it can pass that
current for hours; your cable's insulation, on the other hand, is now
enjoying new heights of devil-may-care flexibility...

Y'see, the Regs is written to reduce - not eliminate, reduce - the need
for detailed analysis, and so that almost all foreseeable installations
which conform with them are safe in practice, in normal use *and* under
fault conditions. Going beyond the envelope of the Regs puts you in
territory where you *may* still be lucky, or you *may* not.

Again, how many rabbit's feet do you have to hand?

There's plenty of ways of arranging a 'temporary' safe-enough feed up to
the loft, which others have already outlined - if it's genuinely
occaisional use, a flex running up a corner of some room or up a
built-in wardrobe or airing cupboard up to a 4-way extension block which
you plug in to a handy-enough socket is safer than fannying about with
putting 13A sockets on lighting or (shudder) shower circuits. Doing a
surface run of cable as a spur - again, taking some
aesthetically-acceptable route - with a good length of slack up in
t'loft ready for when you next redecorate and can sink the cable
properly into the wall, or run it through the studwork wall if that's
how your place is built, is a fully Regs-conformant solution. In short,
there's enough ways of doing the job properly which don't require wall
butchery at an inconvenient time that there's no excuse for bodgery...

Stefek

Pete wrote:

Run it through a fused connection unit with a 5amp fuse, thus there are 2
fuses protecting the socket. yes some could uprate both fuses - but then
again someone could re wire the socket completely.


But will an FCU with a 5amp fuse blow as soon as 5amps of current is
drawn through it? I'll bet it wouldn't, and an MCB is unlikely too
until the circuit has been loaded for some time (unless you can get
really quickly reacting ones). An RCD would not protect against over
current here either, it'd only help if a fault were to arrise but
the damage would already be done then...

I personally don't think there is a great need for a socket in the
loft, after all what could you need to run up there when you are not
up there with it and can therefore use a drum extention lead.

The only things I've ever used in a loft is a lamp, soldering iron
and a power drill... All powered from an extention lead. I guess it's
convinient but I'll bet the OP has an extention lead he can use anyway.

--
Regards,
Aaron.

"Aaron" wrote in message
k...
Pete wrote:

Run it through a fused connection unit with a 5amp fuse, thus there are 2
fuses protecting the socket. yes some could uprate both fuses - but then
again someone could re wire the socket completely.

But will an FCU with a 5amp fuse blow as soon as 5amps of current is
drawn through it? I'll bet it wouldn't, and an MCB is unlikely too
until the circuit has been loaded for some time (unless you can get
really quickly reacting ones). An RCD would not protect against over
current here either, it'd only help if a fault were to arrise but
the damage would already be done then...

I personally don't think there is a great need for a socket in the
loft, after all what could you need to run up there when you are not
up there with it and can therefore use a drum extention lead.


fine for occasional temporary use, not so good or convenient for longer term
or frequent use.

The only things I've ever used in a loft is a lamp, soldering iron
and a power drill... All powered from an extention lead. I guess it's
convinient but I'll bet the OP has an extention lead he can use anyway.


Whereas I have an aerial distribution amplifier, 4 computers, a monitor, a
KVM switch and a network switch permanently up in the loft. 2 double
sockets come in very handy up there.

Useful places, lofts.


--
Richard Sampson

mail me at
richard at olifant d-ot co do-t uk

Aaron wrote:

But will an FCU with a 5amp fuse blow as soon as 5amps of current is
drawn through it? I'll bet it wouldn't, and an MCB is unlikely too
until the circuit has been loaded for some time (unless you can get
really quickly reacting ones).

Well the MCB on my lighting circuit *always* trips when one of the kitchen
spotlight bulbs fail, and last week did so when a 'vanilla' 60w lamp blew.

The only things I've ever used in a loft is a lamp, soldering iron
and a power drill... All powered from an extention lead. I guess it's
convinient but I'll bet the OP has an extention lead he can use anyway.

How would you arrange to power a loft mounted TV aerial booster amp ?

--
Mark
Please replace invalid and invalid with gmx and net to reply

Mark Carver wrote:
How would you arrange to power a loft mounted TV aerial booster amp ?

If it's got a flex, cut the plug off and wire it into a junction box on
the lighting circuit.

If it's the sort that has a plug as part of the case, things are more
awkward. One suggestion has been to glue a single extension socket to
the case, to connect to a length of flex/cable that can be wired in to
the junction box. What is to be avoided is a 13A socket into which other
things could be plugged.

Although if one is running coax cable all round the house for a TV
system it shouldn't be beyond the wit of man to run a spur up to the
loft at the same time.

Owain

In article , Mark Carver
wrote:


How would you arrange to power a loft mounted TV aerial booster amp ?

Cut the plug off and hardwire into a 5A switched spur from the lighting
circuit. You will hardly notice the load.

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

In article ,
Owain writes:
Mark Carver wrote:
How would you arrange to power a loft mounted TV aerial booster amp ?

If it's got a flex, cut the plug off and wire it into a junction box on
the lighting circuit.

If you can find one, a clock point is excellent for this.
They are designed to be connected to a lighting circuit,
can be unplugged for maintenance, and they take a fuse.

--
Andrew Gabriel

How would you arrange to power a loft mounted TV aerial booster amp ?

LIke I have done many times, feed from lighting circuit into FCU, amp
wired directly into FCU with 3 amp fuse or smaller if poss.
Only prob is if amp dies you cannot just unplug.

Dave

Aaron wrote:
Pete wrote:

Run it through a fused connection unit with a 5amp fuse, thus there are 2
fuses protecting the socket. yes some could uprate both fuses - but then
again someone could re wire the socket completely.


But will an FCU with a 5amp fuse blow as soon as 5amps of current is
drawn through it? I'll bet it wouldn't, and an MCB is unlikely too
until the circuit has been loaded for some time (unless you can get
really quickly reacting ones). An RCD would not protect against over
current here either, it'd only help if a fault were to arrise but
the damage would already be done then...

If they don't work then they're not even protecting the lighting
circuit *before* he's added the socket.

Andrew

In article ,
"Christian McArdle" writes:
If you can find one, a clock point is excellent for this.
They are designed to be connected to a lighting circuit,
can be unplugged for maintenance, and they take a fuse.

Are these the same as BS546 round pin sockets?

No, and there's no standard style for them (they aren't
interchangeable between different manufacturers, and
they're sold as a plug and socket matched pair).
Some take the small cartridge fuse used in some shaver
adaptors, and some take a regular BS1362 plugtop fuse.
They were normally available in surface mount or BESA
box mounting types. There's usually a screw or knurled
nut to stop the plug dropping out (not that it's likely
to -- this was probably to act as a bit of a "safety
chain" if the clock fell off the wall).

A fused 2A BS546 round pin plug/socket would be pretty
equivalent.

--
Andrew Gabriel

On Wed, 01 Jun 2005 20:14:07 GMT, GymRatZ wrote:

Strangely.... When we re-wired our on-going project, there was a 2KW
electric fan in the bathroom wired from the lighting circuit.

My workshop dust collector doesn't have a 2kW fan !

I once lived in a flat where the (windowless) bathroom lights were fed
from the shower feed. If you used the pull-cord switch to isolate the
shower, all the lights went out.

Andrew Gabriel wrote:
If it's got a flex, cut the plug off and wire it into a junction box on
the lighting circuit.
If you can find one, a clock point is excellent for this.
They are designed to be connected to a lighting circuit,
can be unplugged for maintenance, and they take a fuse.

A good idea. Clock points are also good for 100V loudspeaker
installations, but not everyone's house boasts a 'tannoy' system.

Owain

wrote:
If they don't work then they're not even protecting the lighting
circuit *before* he's added the socket.

Andrew


Ah but by protection I mean a L-E fault... during which tens of amps
can be drawn very quickly and that would trip the MCB.[1] If you were to
take say 7amps on a 5amp MCB it may not trip straight away. The MCB
uses an electro magnet that generates magnetic flux depending on the
amount of electrons (current) flowing round the coil. As I understand
it, they are designed not to trip when just over the threshold current
is being drawn, because you may well get trips if say you had a fan
light or tube that draws more current than usual when it starts up.

[1] A L-N fault cause by say a bulb blowing and causing one filament
to come in contact with another could also do this since the filament
support wire can drive more current without buring out. I also think
it's worth mentioning that you may not be protected by L-Person fault
since a person may not be able to conduct enough current.. Hence the
modern use of RCD protection.

--
Regards,
Aaron.

In message ,
Aaron wrote:

If you were to take say 7amps on a 5amp MCB it may not trip straight
away. The MCB uses an electro magnet that generates magnetic flux
depending on the amount of electrons (current) flowing round the coil.
As I understand it, they are designed not to trip when just over the
threshold current is being drawn, because you may well get trips if
say you had a fan light or tube that draws more current than usual
when it starts up.

From tables in the back of BS7671:

6A type B MCBs need 30A to trip in 0.4s. They need 13 or 14A to trip
under 100 seconds. 9A looks like about 2,000 seconds. Less than about
8.5A is unlikely to cause it to trip at all. 1mm2 cable is rated up to
16A in normal ("clipped direct") installations, or 12A partly in
insulation.

A 5A BS3036 (rewireable) fuse link needs 24A to blow in 0.4s. 10A will
blow it in about 100 seconds.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... Artificial Intelligence is no match for natural stupidity