Evenin' all,

Although a seasoned DIY sparkie, I would appreciate suggestions for adding
additional SWSOs (Switched Double Socket Outlets) in this scenario. This
particular install is to go behind a television, and power a chunk of AV
gear:

|| cabling (buried in plaster)
||
_______ _________ _________
| | | | | |
--------- ------------ -------------
existing new double new double

Now the cabling runs from ceiling to floor in the lounge of my 'well old'
property! The existing double socket is on a ring. I need to add two others.

IEE 16th Edition regs state that of course, you can only add one DSO (double
socket outlet) as a spur. So do I:

1) Make a joint with choc-block inside the metal box of the exising DSO,
then extend the ring to the new end socket, looping back through the middle
one to the first

or

2) Spur off the first socket using 4.0mm cable, then spur off that (so spur
cable is within spec for two double sockets)

or

3) Bugger the regs and simply add two spurs in daisy-chain format, like
you're not supposed to do!

I call the installation 'strip sockets' because the faceplate of each double
is literally within about 2mm of the next on the wall, allowing neat and
tidy connection of up to six appliances (TV, DVD, Playstation, Terrestrial
Digital (DVB) decoder, etc etc...

Of course, electrically I'd get away with 'spurring off the first spur' -
but I want to keep as close to the regs as possible. Breaking the ring and
installing 30 amp joint boxes is not an option here. Neither is running new
cabling - cables are buried in lime-plaster than is as hard as diamond!

Incidentally, I have installed 'strip sockets' to great effect in my
computer room, giving me a total of 12 sockets by way of six 13 amp doubles.
Only on that occasion, I was able to pick up both sides of the ring under
the floor, and connect one at either end, looping in and out of each new
socket with the requisite 2.5mm sq. T&E.

I'd be eager and grateful to hear suggestions from all who have experience
of doing this type of install in the past. I suppose I'm leaning towards
option (1), with a suitably earthed metal back box.

Many thanks

Alan

In message , Alan
Dempster writes
Evenin' all,

Although a seasoned DIY sparkie, I would appreciate suggestions for adding
additional SWSOs (Switched Double Socket Outlets) in this scenario. This
particular install is to go behind a television, and power a chunk of AV
gear:

|| cabling (buried in plaster)
||
_______ _________ _________
| | | | | |
--------- ------------ -------------
existing new double new double


snip

3) Bugger the regs and simply add two spurs in daisy-chain format, like
you're not supposed to do!

I call the installation 'strip sockets' because the faceplate of each double
is literally within about 2mm of the next on the wall, allowing neat and
tidy connection of up to six appliances (TV, DVD, Playstation, Terrestrial
Digital (DVB) decoder, etc etc...

snip.
I'd be eager and grateful to hear suggestions from all who have experience
of doing this type of install in the past.

I did something similar in the 'office'.

I would suggest 3 - running them as spur with multiple outlets, with one
small change to your plan. supply the spur via a FCU fused at 13 amps,
this makes it reg compliant.

However, not sure i'd bother any more. I'd just have one or two double
sockets and feed them into multiway distribution boards plugged into the
sockets. Our TV/VCR/DVD/STB setup is fed like this. The distribution
strip is fixed tio the back of the TV cabinet and it all is very neat.
--
Chris French, Leeds

chris French wrote:

I would suggest 3 - running them as spur with multiple outlets, with one
small change to your plan. supply the spur via a FCU fused at 13 amps,
this makes it reg compliant.

Either that, or 1 from the OPs list but using crimps rather than choc
blocks since these will fit in the back box much more easily.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In message , John
Rumm writes
chris French wrote:

I would suggest 3 - running them as spur with multiple outlets, with
one small change to your plan. supply the spur via a FCU fused at 13
amps, this makes it reg compliant.

Either that, or 1 from the OPs list but using crimps rather than choc
blocks since these will fit in the back box much more easily.

Indeed.

One advantage of the fused spur route, is that if you use an switched
FCU you can turn everything off in one go.
--
Chris French, Leeds

Alan Dempster wrote:

Evenin' all,

Although a seasoned DIY sparkie, I would appreciate suggestions for adding
additional SWSOs (Switched Double Socket Outlets) in this scenario. This
particular install is to go behind a television, and power a chunk of AV
gear:

|| cabling (buried in plaster)
||
_______ _________ _________
| | | | | |
--------- ------------ -------------
existing new double new double

Now the cabling runs from ceiling to floor in the lounge of my 'well old'
property! The existing double socket is on a ring. I need to add two others.

IEE 16th Edition regs state that of course, you can only add one DSO (double
socket outlet) as a spur. So do I:

1) Make a joint with choc-block inside the metal box of the exising DSO,
then extend the ring to the new end socket, looping back through the middle
one to the first

or

2) Spur off the first socket using 4.0mm cable, then spur off that (so spur
cable is within spec for two double sockets)

or

3) Bugger the regs and simply add two spurs in daisy-chain format, like
you're not supposed to do!

I call the installation 'strip sockets' because the faceplate of each double
is literally within about 2mm of the next on the wall, allowing neat and
tidy connection of up to six appliances (TV, DVD, Playstation, Terrestrial
Digital (DVB) decoder, etc etc...

Of course, electrically I'd get away with 'spurring off the first spur' -
but I want to keep as close to the regs as possible. Breaking the ring and
installing 30 amp joint boxes is not an option here. Neither is running new
cabling - cables are buried in lime-plaster than is as hard as diamond!

Incidentally, I have installed 'strip sockets' to great effect in my
computer room, giving me a total of 12 sockets by way of six 13 amp doubles.
Only on that occasion, I was able to pick up both sides of the ring under
the floor, and connect one at either end, looping in and out of each new
socket with the requisite 2.5mm sq. T&E.

I'd be eager and grateful to hear suggestions from all who have experience
of doing this type of install in the past. I suppose I'm leaning towards
option (1), with a suitably earthed metal back box.

Many thanks

Alan


Best way is to extend one limb of the ring using crimps. Or a chick
block INSIDE a socket, and run a full ring to them.

Thats what I always do.

In uk.d-i-y, chris French wrote:
I'd just have one or two double sockets and feed them into multiway
distribution boards plugged into the sockets. Our TV/VCR/DVD/STB setup
is fed like this. The distribution strip is fixed tio the back of the
TV cabinet and it all is very neat.

Seconded. In the neighbourhood of our TV there are ten mains-operated
boxes. There weren't always that many, of course, but they've arrived
gradually over time. Think ahead to the time that you have ten things to
plug in.

I've fixed distribution strips to the back of the stands with sticky
pads (for flat surfaces) and nylon cable ties (for thin frames).

I've also made extensive use of IEC plugs - like those on the back of a
PC - which save a lot of space. They're especially handy for appliances
that have an IEC inlet, because you can substitute an IEC extension lead
for the lead supplied with the appliance, avoiding the need to cut the
existing lead. IEC distribution boards and extension cables are
available from CPC, Maplin, etc.

--
Mike Barnes

In article , Alan
Dempster writes
Evenin' all,

Although a seasoned DIY sparkie, I would appreciate suggestions for adding
additional SWSOs (Switched Double Socket Outlets) in this scenario. This
particular install is to go behind a television, and power a chunk of AV
gear:

|| cabling (buried in plaster)
||
_______ _________ _________
| | | | | |
--------- ------------ -------------
existing new double new double

Now the cabling runs from ceiling to floor in the lounge of my 'well old'
property! The existing double socket is on a ring. I need to add two others.

IEE 16th Edition regs state that of course, you can only add one DSO (double
socket outlet) as a spur. So do I:

1) Make a joint with choc-block inside the metal box of the exising DSO,
then extend the ring to the new end socket, looping back through the middle
one to the first

or

2) Spur off the first socket using 4.0mm cable, then spur off that (so spur
cable is within spec for two double sockets)

or

3) Bugger the regs and simply add two spurs in daisy-chain format, like
you're not supposed to do!

I call the installation 'strip sockets' because the faceplate of each double
is literally within about 2mm of the next on the wall, allowing neat and
tidy connection of up to six appliances (TV, DVD, Playstation, Terrestrial
Digital (DVB) decoder, etc etc...

Of course, electrically I'd get away with 'spurring off the first spur' -
but I want to keep as close to the regs as possible. Breaking the ring and
installing 30 amp joint boxes is not an option here. Neither is running new
cabling - cables are buried in lime-plaster than is as hard as diamond!

Incidentally, I have installed 'strip sockets' to great effect in my
computer room, giving me a total of 12 sockets by way of six 13 amp doubles.
Only on that occasion, I was able to pick up both sides of the ring under
the floor, and connect one at either end, looping in and out of each new
socket with the requisite 2.5mm sq. T&E.

I'd be eager and grateful to hear suggestions from all who have experience
of doing this type of install in the past. I suppose I'm leaning towards
option (1), with a suitably earthed metal back box.

Why don't you just extend the ring to encompass the new sockets, not
bother with spurs at all
--
David

On Thu, 17 Feb 2005 08:13:40 +0000, chris French wrote:

One advantage of the fused spur route, is that if you use an
switched FCU you can turn everything off in one go.

This would be my approach for that reason, Switched FCU positioned so
as to be reachable... Of course some stuff you don't want to switch
off so I think I'd end up with a the existing double socket feeding a
trailing socket unit for the premenantly live stuff (if more than two)
then a SW'd FCU to another double socket and trailing socket unit for
the switched stuff.

This way you can easyly adjust the number of sockets on each side by
getting the appropiate trailing extension. These trailing thingies
normally have the abilty to be fixed to a surface so the whole thing
can be very neat and not floating about.

--
Cheers
Dave. pam is missing e-mail

chris French wrote:
In message , Alan
Dempster writes

Evenin' all,

Although a seasoned DIY sparkie, I would appreciate suggestions for
adding
additional SWSOs (Switched Double Socket Outlets) in this scenario. This
particular install is to go behind a television, and power a chunk of AV
gear:

|| cabling (buried in plaster)
||
_______ _________ _________
| | | | | |
--------- ------------ -------------
existing new double new double


snip

3) Bugger the regs and simply add two spurs in daisy-chain format, like
you're not supposed to do!

I call the installation 'strip sockets' because the faceplate of each
double
is literally within about 2mm of the next on the wall, allowing neat and
tidy connection of up to six appliances (TV, DVD, Playstation,
Terrestrial
Digital (DVB) decoder, etc etc...

snip.

I'd be eager and grateful to hear suggestions from all who have
experience
of doing this type of install in the past.


I did something similar in the 'office'.

I would suggest 3 - running them as spur with multiple outlets, with one
small change to your plan. supply the spur via a FCU fused at 13 amps,
this makes it reg compliant.

However, not sure i'd bother any more. I'd just have one or two double
sockets and feed them into multiway distribution boards plugged into the
sockets. Our TV/VCR/DVD/STB setup is fed like this. The distribution
strip is fixed tio the back of the TV cabinet and it all is very neat.


I'd definitely go with a couple of 6 way distribution boards, personally. I
can't see any justification for going down the 3 double sockets root, both
from an aesthetic and needless work point of view. Unless the OP has some
very esoteric AV kit nothing is going to draw much power, and there is no
need for individual sockets.


If this lot is visible, then 3 double sockets next to each other is going to
look pretty poor. In which case if you use the dist. boards most of the
wiring can be hidden.

If it's not visible then screw the dist. boards to the wall if you want.

cheers

David

Alan Dempster wrote:

So do I:

1) [...] extend the ring to the new end socket, looping back through the middle
one to the first

2) [...] Spur off the first socket using 4.0mm cable, then spur off that

3) Bugger the regs and simply add two spurs in daisy-chain format, like
you're not supposed to do!

I might plump for:

4) Two separate unfused spurs in 2.5 mm^2 taken from the existing socket
(with the cable for the furthest socket run through the middle mounting
box, but not connected to anything therein).

Another possibility would be:

5) Instead of 3 doubles, use two 3-gang sockets (like MK K2737WHI) with
the first on the ring (replacing the existing double) and the second as
a spur. Since the 3-gang sockets incorporate a 13A fuse the spur will
count as fused and no rules will be violated.

--
Andy

snip

3) Bugger the regs and simply add two spurs in daisy-chain format, like
you're not supposed to do!


Dumb question time!

I know that you are not supposed to take more than one socket off a ring
as a spur but have never figured out why! Can anyone enlighten me?

Cuprager wrote:

Dumb question time!

I know that you are not supposed to take more than one socket off a ring
as a spur but have never figured out why! Can anyone enlighten me?

Several reasons....

Firstly there is the issue of the cable. On a ring, each socket will be
fed by two cables, either of which will carry the full load current of
the socket. Hence if you spur from the ring with one similar cable there
is little danger of causing damage to the cable with an overload. If
however you add several sockets to that spur cable then you run the risk
of exceeding its capacity. That is why the regs require the introduction
of a fuse into the spur if you are going to do this.

The second issue is that of load distribution. Rings work well as a
result of both diversity (i.e. the statistical likelihood that only a
small proportion of the actual maximum load will ever be required at any
one time), and the fact the loads will be spread around the ring. A ring
with all the load concentrated at one end, could for example, overload
the short cable run back to the CU since it would have a proportionately
lower resistance than the longer run, and hence carry more than its
"fair share" of the current. So again adding lots of sockets to a single
spur (even if you wire it in heavier cable so as to not allow the spur
to overload), you will still be concentrating a large load on to a
single point on the ring.

Other issues: fault loop impedance; a ring socket will have two earth
wires connecting to each socket, while a large spur will have ultimately
half the total earth conductor size/area. Hence the resistance to earth
from a spur socket is likely to be a bit higher than for a ring one. The
longer you make it and the more sockets you add the worse this gets.
Hence you potentially lower safety since the fault current that can flow
to earth is reduced, and the time to blow/trip the protective fuse or
breaker gets longer.

Maintenance: there is the danger than someone will mistake a socket on a
multiple spur as a part of a ring (since it will have a cable in and out
and hence look like a part of the ring). Adding to the possibility that
later modifications will increase the risk of overload.

Increased testing time: testing a ring is relatively simple using a low
ohms meter at various points with the conductors cross connected (and
disconnected from the CU!). Each spur adds complexity to the process.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

snip enlightening response

Thank you for that really great explanation! Now I know...

Cuprager wrote:

I know that you are not supposed to take more than one socket off a ring
as a spur but have never figured out why! Can anyone enlighten me?

For "spur" read "unfused spur." There's no limit if it's a fused spur
of up to 13 A (subject of course to consideration of the load likely to
be connected).

Unfused spurs are restricted to one single or double socket (or one item
of fixed equipment) because:

a) the rating of 2.5 mm^2 cable is assumed to be 20 A, but the circuit's
overcurrent protective device is 30 or 32 A, so does not provide
overload protection to the spur. Spurs rely on the plug or fused
connection unit fuse(s) to protect the cable. It's assumed that the
load on a double socket is unlikely in practice to exceed 20 A[*], but
with two singles there's much more risk of 26 amps worth of load being
connected, which could overload the cable;

b) even if you used 4 mm^2 cable to overcome the first objection it's
undesirable to connect a large load at one point on the ring (especially
a point near to one end. The ring circuit works on the principle that
the load is will be reasonably evenly distributed along its length.
Ignoring that principle greatly increases the risk of cable overload
occurring.
[*] Beware of the risk of violating this in the context of kitchen &
laundry appliances.

--
Andy

Hey Andy, thanks for your input!


I might plump for:

4) Two separate unfused spurs in 2.5 mm^2 taken from the existing socket
(with the cable for the furthest socket run through the middle mounting
box, but not connected to anything therein).


I like it - still not stricltly 'cosher' because there's two spurs
effectively from the same original DSO, but at least the cable is protected
to being used within its load limit.


Nice one!

Now to struggle with four lots of 2.5mm sq. conductors in the one socket.
Deep joy (in a deep box!!!)

Cheers

Al.

Andy Wade wrote:

connection unit fuse(s) to protect the cable. It's assumed that the
load on a double socket is unlikely in practice to exceed 20 A[*], but
with two singles there's much more risk of 26 amps worth of load being
connected, which could overload the cable;
(snip)
[*] Beware of the risk of violating this in the context of kitchen &
laundry appliances.

Is it considered acceptable to have both a tumble dryer and a washing
machine using the same double socket?

Sheila

S Viemeister wrote:


Is it considered acceptable to have both a tumble dryer and a washing
machine using the same double socket?

No need to worry in practice: a woshmosh runs at its peak of 2 or 2.5kW
only while it's actually heating water, typically only for 15 mins or so
at the start of the cycle; while your "normal" tumble dryer is likely
also to have a 2.5kW heater, and will run at less than 100%
on-all-the-time even when doing wet towels on the highest setting. The
peak load will be 5kW, which near as damn it is 20A (5000/240 = 20.8A,
divide my 5kW by 230 if you want to pretend UK mains is 230V to get
21.7A if you want to panic, but you won't convince me a 240V-design
heater will pull its full kW rating running at that slightly lower
voltage ;-). So, even when both appliances' heaters are on, there's only
the 20A flowing through the double socket, and no decent-quality socket
with incoming conductors sensibly tightened will run anything above
slightly warm...

More, and authoritative, detail over at
http://www.iee.org/Publish/WireRegs/Amd1andRC.pdf

S Viemeister wrote:

Andy Wade wrote:


connection unit fuse(s) to protect the cable. It's assumed that the
load on a double socket is unlikely in practice to exceed 20 A[*], but
with two singles there's much more risk of 26 amps worth of load being
connected, which could overload the cable;

(snip)

[*] Beware of the risk of violating this in the context of kitchen &
laundry appliances.


Is it considered acceptable to have both a tumble dryer and a washing
machine using the same double socket?


Sure. Why not?

Sheila

Alan Dempster wrote:

I like it - still not stricltly 'cosher' because there's two spurs
effectively from the same original DSO, but at least the cable is protected
to being used within its load limit.

It's 100% kosher. Nothing in the rules for spurs (Appendix 8 of the IEE
On-Site Guide) forbids two separate spurs being connected to the ring at
the same point.

There is an overriding consideration though, in the form of Reg.
433-02-04 of BS 7671 itself, which includes the words:

" [...] Such ring final circuits are deemed to meet the requirements of
Regulation 433-02-01 if the current-carrying capacity (Iz) of the cable
is not less than 20 A, and if, under_the_intended_conditions_of_use, the
load current _in_any_part_of_the_ring_ is unlikely to exceed for long
periods the current-carrying capacity (Iz) of the cable." [My emphasis,
and note that Iz is the _as_installed_ cable rating.]

Now to struggle with four lots of 2.5mm sq. conductors in the one socket.
Deep joy (in a deep box!!!)

That should not be a problem with double-gang sockets of reputable origin.

--
Andy

The Natural Philosopher wrote:

Sure. Why not?

Not if you know that a sustained RMS current demand of over 20 A will
occur; that's when not.

--
Andy

Andy Wade wrote:

The Natural Philosopher wrote:

Sure. Why not?


Not if you know that a sustained RMS current demand of over 20 A will
occur; that's when not.


On two sockets? The ones I have installed have busbars fullty capable if
stri=butuing 13A to either socket without oiverheating. Once past teh
actual screw down termination (to which oboth pairs of te ring go) the
bars split towards teh two sockets, and are far more substantial than
teh wiring in cross section, so wheres the problem?

The ONLY case I have ever had of plug or socket fauilure have been in a
single plug or socket that has suffered ARCING, or corrosion and then
arcing.

That's a problem almost irrespective of how many appliances are plugged
into it. Since ehat is plugged in is essentially 13A limited.

The Natural Philosopher wrote:

On two sockets? The ones I have installed have busbars fullty capable if
stri=butuing 13A to either socket without oiverheating. Once past teh
actual screw down termination (to which oboth pairs of te ring go) the
bars split towards teh two sockets, and are far more substantial than
teh wiring in cross section, so wheres the problem?

This topic comes up from time to time. BS 1363 only requires double
socket-outlets to be type-tested at 20 A total load. The assumption
that this will be the max. load on a double socket permeates the wiring
regs. - the cable to a double socket on an unfused spur, for example,
might only be rated to carry 20 A.

You can't just assume a 26 A rating, although several manufacturers'
products are so rated. E.g. I rang MK about this during one of the
previous threads on this and they said theirs are OK for the full 26 A,
provided the wiring is also capable of that current.

Best practice in kitchens of course is to provide dedicated single
socket outlets (or FCUs) for the large appliances, each with a separate
control switch in an accessible location.

The ONLY case I have ever had of plug or socket fauilure have been in a
single plug or socket that has suffered ARCING, or corrosion and then
arcing.

IME most problems are caused (or rather start) in the plug and result
from loose terminal screws or dirty fuse contacts. The plug pin(s) -
usually the L pin - overheats and then damages the socket. The heat
de-tempers the socket's spring contact, increasing contact resistance
there and generating more heat: positive feedback, thermal runaway,
fishy smell... That said, such problems seem to have become much rarer
since the Plugs & Sockets (Safety) Regulations came in to force,
requiring 3rd party approval for all products.

--
Andy

"Andy Wade" wrote in message
...
The Natural Philosopher wrote:

On two sockets? The ones I have installed have busbars fullty capable if
stri=butuing 13A to either socket without oiverheating. Once past teh
actual screw down termination (to which oboth pairs of te ring go) the
bars split towards teh two sockets, and are far more substantial than
teh wiring in cross section, so wheres the problem?

This topic comes up from time to time. BS 1363 only requires double
socket-outlets to be type-tested at 20 A total load. The assumption
that this will be the max. load on a double socket permeates the wiring
regs. - the cable to a double socket on an unfused spur, for example,
might only be rated to carry 20 A.

You can't just assume a 26 A rating, although several manufacturers'
products are so rated. E.g. I rang MK about this during one of the
previous threads on this and they said theirs are OK for the full 26 A,
provided the wiring is also capable of that current.

Best practice in kitchens of course is to provide dedicated single
socket outlets (or FCUs) for the large appliances, each with a separate
control switch in an accessible location.

MEM do a central switch box with labled breakers: cooker, fridge, etc. This
can be in a separate cupboard, or outside the kitchen. Spare cables can be
run to the kitchen is case of expansion.

This may get you past Part P, as virtaully all of the work is outside the
kitchen



_________________________________________
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Doctor Evil wrote:

MEM do a central switch box with labled breakers: cooker, fridge, etc. This
can be in a separate cupboard, or outside the kitchen.

Wrong - it should be readily accessible within the kitchen. There has
been recent clarification[*] from the IEE that hiding control switches
in cupboards is not acceptable.
[*] http://www.iee.org/Publish/WireRegs/...Matters_15.pdf - see "good
practice in kitchens" starting on p.13 of the PDF.

This may get you past Part P, as virtaully all of the work is outside the
kitchen

That's nonsense too.

--
Andy

On Sun, 20 Feb 2005 10:55:25 -0000, "Doctor Evil"
strung together this:

MEM do a central switch box with labled breakers: cooker, fridge, etc. This
can be in a separate cupboard, or outside the kitchen. Spare cables can be
run to the kitchen is case of expansion.

This may get you past Part P, as virtaully all of the work is outside the
kitchen

Er, no. Stick to talking ******** about plumbing and stop intefering
in electrics.
--

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

"Andy Wade" wrote in message
...
Doctor Evil wrote:

MEM do a central switch box with labled breakers: cooker, fridge, etc.
This
can be in a separate cupboard, or outside the kitchen.

Wrong - it should be readily accessible within the kitchen. There has
been recent clarification[*] from the IEE that hiding control switches
in cupboards is not acceptable.

Oh dear - I think that is going to end up in court then. There is no way
those buying top end 'dream' kitchen manufacturers are going to accept
ghastly control switches being on display. And suppliers charging £50k up
do at least expect to deliver what the client asks for.