Our house was built around the early to mid 60s (so has "modern" PVC twin &
earth cabling) and has just one ring main feeding the whole house. We want
to add in some extra sockets but obviously I don't want to overload the one
circuit so I've had an idea that I want to run past you peeps here.

Most family/friends houses seem to be wired with an upstairs ring and a
downstairs ring. My idea is to go to all the sockets in the upstairs rooms
and basically pull the cables out of the sockets, back down to under the
floorboards and joint them there (either with "traditional" junction boxes
or with crimps/heatshrink sleeve), so that the continuity of the ring is
preserved but it is now just serving the downstairs sockets, then run a new
ring for the upstairs sockets, and adding new sockets to each ring where
needed.

Is this OK?

TIA,
Bill

Bill Payer
wibbled on Monday 19 October 2009 12:07

Our house was built around the early to mid 60s (so has "modern" PVC twin
& earth cabling) and has just one ring main feeding the whole house. We
want to add in some extra sockets but obviously I don't want to overload
the one circuit so I've had an idea that I want to run past you peeps
here.

Most family/friends houses seem to be wired with an upstairs ring and a
downstairs ring. My idea is to go to all the sockets in the upstairs rooms
and basically pull the cables out of the sockets, back down to under the
floorboards and joint them there (either with "traditional" junction boxes
or with crimps/heatshrink sleeve), so that the continuity of the ring is
preserved but it is now just serving the downstairs sockets, then run a
new ring for the upstairs sockets, and adding new sockets to each ring
where needed.

Is this OK?

TIA,
Bill

In principle it sounds fine. Crimps would be an excellent way to joint the
cable provided that you have a proper crimping tool and are happy with how
it's enclosed. Another way, if you are concerned about the accessibility of
the joints is one of the new Hager Ashley maintenance free junction boxes:

http://www.tlc-direct.co.uk/Products/ASJ803.html

Those have spring contacts and good cable clamps and IME (of the smaller
lighting ones) *very* well made.

The only 3 flies in the ointment AFAICS (other may see more):

a) Is your cable in good condition after 40 years? Even PVC has a finite
life.

b) Depending on how well you can see the cables being run, you have to watch
out for the possibility of creating an incorrect ring by mistake (eg 2
radials or a figure of 8 ring). it would be worth testing as you go to
ensure that the cable you are about to joint is going where you think.

c) Part P - whatever... But for something like this, it would be worth
borrowing a Megger or similar and actually testing the resultant ring for
peace of mind at every socket outlet. Then you can prove there are no
insideous wiring errors (perhaps resulting from the original circuit, like
a broken or loose conductor somewhere you can't see) and that the
insulation is still good.

Another approach could be to break the original ring deliberately into 2 or
more 20A radials - this might be simpler if it leaves you with a reasonable
distribution, though your kitchen/utility room might scupper this with a
large presence of high loads in one place?... There're no real restrictions
on radial topology if you can be sure that 20A is enough for each circuit.

HTH

Tim
--
Tim Watts

This space intentionally left blank...

Tim W wrote:
Bill Payer
wibbled on Monday 19 October 2009 12:07

Our house was built around the early to mid 60s (so has "modern" PVC
twin & earth cabling) and has just one ring main feeding the whole
house. We want to add in some extra sockets but obviously I don't
want to overload the one circuit so I've had an idea that I want to
run past you peeps here.

Most family/friends houses seem to be wired with an upstairs ring
and a downstairs ring. My idea is to go to all the sockets in the
upstairs rooms and basically pull the cables out of the sockets,
back down to under the floorboards and joint them there (either with
"traditional" junction boxes or with crimps/heatshrink sleeve), so
that the continuity of the ring is preserved but it is now just
serving the downstairs sockets, then run a new ring for the upstairs
sockets, and adding new sockets to each ring where needed.

Is this OK?

TIA,
Bill

In principle it sounds fine. Crimps would be an excellent way to
joint the cable provided that you have a proper crimping tool and are
happy with how it's enclosed. Another way, if you are concerned about
the accessibility of the joints is one of the new Hager Ashley
maintenance free junction boxes:

http://www.tlc-direct.co.uk/Products/ASJ803.html

Those have spring contacts and good cable clamps and IME (of the
smaller lighting ones) *very* well made.

The only 3 flies in the ointment AFAICS (other may see more):

a) Is your cable in good condition after 40 years? Even PVC has a
finite life.

Thanks for the quick reply Tim! )

You make good points there. I've taken some of the sockets off and all
connections look to be clean and tight with no signs of
burning/brittleness/overloading and I've had a couple of the floorboards up
and can see no signs of any damage. Visually, everything looks OK.

b) Depending on how well you can see the cables being run, you have
to watch out for the possibility of creating an incorrect ring by
mistake (eg 2 radials or a figure of 8 ring). it would be worth
testing as you go to ensure that the cable you are about to joint is
going where you think.

Noted

c) Part P - whatever... But for something like this, it would be worth
borrowing a Megger or similar and actually testing the resultant ring
for peace of mind at every socket outlet. Then you can prove there
are no insideous wiring errors (perhaps resulting from the original
circuit, like a broken or loose conductor somewhere you can't see)
and that the insulation is still good.

Will do. I'll also test the existing cabling before starting any work to
supplement the visual as in your (a) above.

Another approach could be to break the original ring deliberately
into 2 or more 20A radials - this might be simpler if it leaves you
with a reasonable distribution, though your kitchen/utility room
might scupper this with a large presence of high loads in one
place?... There're no real restrictions on radial topology if you can
be sure that 20A is enough for each circuit.

Hmm, that's a thought. Thanks Tim.

Bill

On Oct 19, 12:07*pm, "Bill Payer" wrote:
Our house was built around the early to mid 60s (so has "modern" PVC twin &
earth cabling) and has just one ring main feeding the whole house. We want
to add in some extra sockets but obviously I don't want to overload the one
circuit so I've had an idea that I want to run past you peeps here.

Most family/friends houses seem to be wired with an upstairs ring and a
downstairs ring. My idea is to go to all the sockets in the upstairs rooms
and basically pull the cables out of the sockets, back down to under the
floorboards and joint them there (either with "traditional" junction boxes
or with crimps/heatshrink sleeve), so that the continuity of the ring is
preserved but it is now just serving the downstairs sockets, then run a new
ring for the upstairs sockets, and adding new sockets to each ring where
needed.

Is this OK?

TIA,
Bill

Its entirely pointless, unless of course you run a lot of large loads
upstairs, for reasons I cant imagine.

Splitting the ring into 2x 20A circuits doesn't gain you anything
much, and only worsens its safety performance.

The only place your average 2 bed house would benefit from a 2nd ring
is the kitchen, where the heavy loads live. But even then, as you
already know, in practice one can run a whole house on a single ring.


NT

NT wrote:
Its entirely pointless, unless of course you run a lot of large loads
upstairs, for reasons I cant imagine.

Splitting the ring into 2x 20A circuits doesn't gain you anything
much, and only worsens its safety performance.

The only place your average 2 bed house would benefit from a 2nd ring
is the kitchen, where the heavy loads live. But even then, as you
already know, in practice one can run a whole house on a single ring.

We've got a similar problem in that we have solid floors downstairs so
all of the ring mains will need to run in the suspended ceilings. The
trouble being that there is a 50m cable length limit on the ring main,
and you use up about 4.5m each socket coming down from the ceiling then
back up.

Unfortunately the windows come too low down on the wall to run across
underneath them, and there are doors/chimney breasts to get in the way
as well.

I was thinking it might be possible to run a thick cable out to some
kind of junction box, then spurs out to each socket rather than a ring -
I don't know if that's allowed under the wiring regs?

In article ,
Bill Payer wrote:
Our house was built around the early to mid 60s (so has "modern" PVC
twin & earth cabling) and has just one ring main feeding the whole
house. We want to add in some extra sockets but obviously I don't want
to overload the one circuit so I've had an idea that I want to run past
you peeps here.

Most family/friends houses seem to be wired with an upstairs ring and a
downstairs ring. My idea is to go to all the sockets in the upstairs
rooms and basically pull the cables out of the sockets, back down to
under the floorboards and joint them there (either with "traditional"
junction boxes or with crimps/heatshrink sleeve), so that the
continuity of the ring is preserved but it is now just serving the
downstairs sockets, then run a new ring for the upstairs sockets, and
adding new sockets to each ring where needed.

Is this OK?

I'd say it's making too many unnecessary joints. Do you know where the
ring goes upstairs and back down again? You might well find they are
together. Also if you intend keeping the existing socket positions
upstairs it's making more work.

Other thing is the ECC on older TW&E is smaller than currently. Not quite
sure how that effects radical alteration. But my gut feeling would be to
keep the old ring as short as possible.

TIA,
Bill

--
*Stable Relationships Are For Horses. *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Tim W writes:

In principle it sounds fine. Crimps would be an excellent way to joint the
cable provided that you have a proper crimping tool and are happy with how
it's enclosed. Another way, if you are concerned about the accessibility of
the joints is one of the new Hager Ashley maintenance free junction boxes:

http://www.tlc-direct.co.uk/Products/ASJ803.html

Those have spring contacts and good cable clamps and IME (of the smaller
lighting ones) *very* well made.

In my view, these are unsuitable for inaccessible connections and do
not comply with the regs for this purpose.

Ashley's use of "maintenance free" would appear to mean they provide
no means to perform any maintenance, not that none would be required.
Indeed, with the absence of large surface area gas-tight contacts
which are present in all the proscribed [maintenance free] methods for
inaccessible connections, I would expect a shorter lifetime from this
product than from standard screw terminals, and as such, thoroughly
unsuitable for an inaccessible connection.

Not used one myself though.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Mon, 19 Oct 2009 13:21:07 +0100 someone who may be Jim
wrote this:-

I was thinking it might be possible to run a thick cable out to some
kind of junction box, then spurs out to each socket rather than a ring -
I don't know if that's allowed under the wiring regs?

The Wiring Regulations offer a variety of standard solutions, for
want of better words. Many people think they are all that can be
used.

However, one is not restricted to using these standard solutions, in
fact they encourage innovation. There is a space on the forms IET
offer which allows one to list departures from the standard
solutions. However, if one does use something non-standard then it
has to provide at least an equivalent level of protection to the
standard solution. If it comes to it one may need to be able to
demonstrate this in a court, so may people sensibly stick to the
standard solutions.

If someone wanted to use say Schuko sockets in a building they would
have to wire them up to provide an equivalent level of safety. No
ring final circuits, suitably small floor areas, RCDs, double pole
circuit breakers and double pole switching, off the top of my head,
would provide an equivalent level of safety, but that is only off
the top of my head. There are few places where it makes any sense to
do this though.

Your proposed circuit would be non standard. Provided it was
designed, installed and documented properly no problem. Do you have
the skills to do this?



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000...#pt3-pb3-l1g54

Dave Plowman (News) wrote:
In article ,
Bill Payer wrote:
Our house was built around the early to mid 60s (so has "modern" PVC
twin & earth cabling) and has just one ring main feeding the whole
house. We want to add in some extra sockets but obviously I don't
want to overload the one circuit so I've had an idea that I want to
run past you peeps here.

Most family/friends houses seem to be wired with an upstairs ring
and a downstairs ring. My idea is to go to all the sockets in the
upstairs rooms and basically pull the cables out of the sockets,
back down to under the floorboards and joint them there (either with
"traditional" junction boxes or with crimps/heatshrink sleeve), so
that the continuity of the ring is preserved but it is now just
serving the downstairs sockets, then run a new ring for the upstairs
sockets, and adding new sockets to each ring where needed.

Is this OK?

I'd say it's making too many unnecessary joints. Do you know where the
ring goes upstairs and back down again? You might well find they are
together. Also if you intend keeping the existing socket positions
upstairs it's making more work.

Well, this is rather the point in doing the job in the first place, ie, we
don't have enough sockets. It's a three-bedroomed house with just one
double-socket in each room and a single socket out on the landing, so doing
it the way I originally thought would leave four joints under the
floorboards. Is that too many?

Other thing is the ECC on older TW&E is smaller than currently. Not
quite sure how that effects radical alteration. But my gut feeling
would be to keep the old ring as short as possible.

TIA,
Bill

David Hansen wrote:
On Mon, 19 Oct 2009 13:21:07 +0100 someone who may be Jim
wrote this:-

I was thinking it might be possible to run a thick cable out to some
kind of junction box, then spurs out to each socket rather than a ring -
I don't know if that's allowed under the wiring regs?
[...]
Your proposed circuit would be non standard. Provided it was
designed, installed and documented properly no problem. Do you have
the skills to do this?

We have a qualified electrician doing the specification and
commissioning. I've just been looking at the regulations and trying to
figure things out so I can have meaningful conversations with him.

Surely my "proposed circuit" could be considered as a radial with
multiple spurs? In which case it could have as many spurs as necessary
so long as the cable length limit from CU to socket wasn't exceeded.

Andrew Gabriel
wibbled on Monday 19 October 2009 13:35

In article ,
Tim W writes:

In principle it sounds fine. Crimps would be an excellent way to joint
the cable provided that you have a proper crimping tool and are happy
with how it's enclosed. Another way, if you are concerned about the
accessibility of the joints is one of the new Hager Ashley maintenance
free junction boxes:

http://www.tlc-direct.co.uk/Products/ASJ803.html

Those have spring contacts and good cable clamps and IME (of the smaller
lighting ones) *very* well made.

In my view, these are unsuitable for inaccessible connections and do
not comply with the regs for this purpose.

Ashley's use of "maintenance free" would appear to mean they provide
no means to perform any maintenance, not that none would be required.
Indeed, with the absence of large surface area gas-tight contacts
which are present in all the proscribed [maintenance free] methods for
inaccessible connections, I would expect a shorter lifetime from this
product than from standard screw terminals, and as such, thoroughly
unsuitable for an inaccessible connection.

Not used one myself though.


Indeed. These things (Ashley in particular) keep getting mentioned on the
IET forums in exactly this context and opinion goes both ways.

Obviously Hager are strongly hinting that they are suitable. all I can do is
quote:

"The screwless push to fit terminals do not relax, and so do not require
inspection." from:

http://www.hager.co.uk/building-auto...tures/6387.htm

It would be interesting to challenge them on the specifics.


You're an engineer and obviously your opinion is worth much and I can see
your argument.


I've used them in a semi-accessible location (under floorboards), where
there's some flex in use (SELV downlighters, I use high temperature
silicone flex) and they are very good for this (because the contacts are
suitable for solid or flexible and the cable clamps being present).

I should note that the springs are pretty strong in these. Whether the
springiness can be proven not to decline in time or whether the contact
pressure is sufficient to prevent oxidation of the cable I couldn't
comment.

Cheers

Tim

--
Tim Watts

This space intentionally left blank...

NT
wibbled on Monday 19 October 2009 13:14

On Oct 19, 12:07*pm, "Bill Payer" wrote:
Our house was built around the early to mid 60s (so has "modern" PVC twin
& earth cabling) and has just one ring main feeding the whole house. We
want to add in some extra sockets but obviously I don't want to overload
the one circuit so I've had an idea that I want to run past you peeps
here.

Most family/friends houses seem to be wired with an upstairs ring and a
downstairs ring. My idea is to go to all the sockets in the upstairs
rooms and basically pull the cables out of the sockets, back down to
under the floorboards and joint them there (either with "traditional"
junction boxes or with crimps/heatshrink sleeve), so that the continuity
of the ring is preserved but it is now just serving the downstairs
sockets, then run a new ring for the upstairs sockets, and adding new
sockets to each ring where needed.

Is this OK?

TIA,
Bill

Its entirely pointless, unless of course you run a lot of large loads
upstairs, for reasons I cant imagine.

Splitting the ring into 2x 20A circuits doesn't gain you anything
much, and only worsens its safety performance.

The only place your average 2 bed house would benefit from a 2nd ring
is the kitchen, where the heavy loads live. But even then, as you
already know, in practice one can run a whole house on a single ring.


NT

I'm putting 4 rings in my house. 1.5 for the kitchen/diner (the other 0.5
serves utility and one bedroom), one for the rest of the ground floor and
one upstairs. It's not necessarily the case that the loads demand it, but
it's geographically convenient and povides sensible seggregation in the
event of one circuit tripping (ie I don't lose the whole house).



--
Tim Watts

This space intentionally left blank...

Single ring does not comply with 314.1, may not be "balanced" re all
kitchen loads at one end. Many councils will reject a single ring
based on the latter.

Breaking into two 20A radials doesn't gain much.

20A radials are good in quantity - that is one per room (lots of PCs,
rented) and multiple in a kitchen (fridge/freezer, washer/kettle,
dryer/microwave, fan heater). Quantity provides redundancy and
localises any earth leakage fault (cable fault, element fault). 20A
radials have a safety benefit in that a 2G socket is limited to 19.5A
continuous, whereas downstream protection is 13+13A and upstream CPD
on a ring would be 32A. The benefit of a radial is topology - whatever
you want.

32A rings are good in quantity - minimum of two unless you know the
ring will be balanced (not likely). 32A rings have a safety benefit in
that there are 2 paths for earth, so effectively reducing EFLI
although that is less critical with RCD protection. The downside of
rings is the topology must be a ring, not always easy in some houses
(and decoration!).

32A radials are a good compromise using 4mm FTE - still rare in
domestic, but practically very useful in a kitchen environment. Note
that Grid Switches are limited to 20A circuits, but then I suspect a
kitchen could have a single 32A isolator re "emergency isolation" or
isolation for all appliances (burning microwave, removal of built-in
appliances).

I personally prefer lots of 20A radials re 314.1 redundancy,
topological flexibility & expansion flexibility.

However for the OP I would break the kitchen off into its own 32A ring
for 314.1, then have the house on its own ring. It might be very
convenient physically to do this.

Bill Payer wrote:
Dave Plowman (News) wrote:
In article ,
Bill Payer wrote:
Our house was built around the early to mid 60s (so has "modern" PVC
twin & earth cabling) and has just one ring main feeding the whole
house. We want to add in some extra sockets but obviously I don't
want to overload the one circuit so I've had an idea that I want to
run past you peeps here.

Most family/friends houses seem to be wired with an upstairs ring
and a downstairs ring. My idea is to go to all the sockets in the
upstairs rooms and basically pull the cables out of the sockets,
back down to under the floorboards and joint them there (either with
"traditional" junction boxes or with crimps/heatshrink sleeve), so
that the continuity of the ring is preserved but it is now just
serving the downstairs sockets, then run a new ring for the upstairs
sockets, and adding new sockets to each ring where needed.

Is this OK?

I'd say it's making too many unnecessary joints. Do you know where
the ring goes upstairs and back down again? You might well find they
are together. Also if you intend keeping the existing socket
positions upstairs it's making more work.

Well, this is rather the point in doing the job in the first place,
ie, we don't have enough sockets. It's a three-bedroomed house with
just one double-socket in each room and a single socket out on the

Doh! That should be one double socket in each BEDroom, not, as you may have
thought, each room of the house - sorry.

landing, so doing it the way I originally thought would leave four
joints under the floorboards. Is that too many?

Other thing is the ECC on older TW&E is smaller than currently. Not
quite sure how that effects radical alteration. But my gut feeling
would be to keep the old ring as short as possible.

TIA,
Bill

Bill Payer wrote:

Well, this is rather the point in doing the job in the first place, ie, we
don't have enough sockets.

Bear in mind that adding more sockets isn't likely to significantly increase
the loading which is dependent on the number and power rating of the
appliances you use. So, unless you intend to get lots more high power
appliances, adding more sockets to the existing ring won't be a problem. In
fact it will probably make the whole installation much safer if it means
using less multiway adaptors and trailing extension leads.

--
Mike Clarke

On Mon, 19 Oct 2009 13:57:51 +0100 someone who may be Jim
wrote this:-

We have a qualified electrician doing the specification and
commissioning.

Electricians come in variable forms. Some just want to stick to the
standard solutions and select cable sizes from a table. Others are
very good and happy to do calculations if you pay them enough.

Surely my "proposed circuit" could be considered as a radial with
multiple spurs? In which case it could have as many spurs as necessary
so long as the cable length limit from CU to socket wasn't exceeded.

I see from re-reading your posting that you are not proposing a
large cable leading to a ring, as I wrongly assumed.

You could use a standard 20A radial circuit, without the thick
cable, provided that the floor areas were complied with.

You could also set up an non-standard radial circuit with the thick
cable, but you would need calculations done to see that all the
cables were properly protected. It may be the case that say a 32A
protective device which protected the thick cable did not adequately
protect "normal" 2.5 mm cable. There are a number of conditions to
meet when sizing cables and protective devices.




--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000...#pt3-pb3-l1g54

In article ,
Tim W writes:

I'm putting 4 rings in my house. 1.5 for the kitchen/diner (the other 0.5
serves utility and one bedroom), one for the rest of the ground floor and
one upstairs. It's not necessarily the case that the loads demand it, but
it's geographically convenient and povides sensible seggregation in the
event of one circuit tripping (ie I don't lose the whole house).

Last couple of kitchens I've done (16th Ed regs), I put two rings
into each, one RCD protected for the accessible socket outlets,
and one non-RCD protected for stationary/fixed appliances such as
fridge, freezer, oven, boiler, etc, which you don't want sharing
an RCD with anything else, and don't merit one themselves.

Thus far, I always used 30mA RCBO's per circuit (or 10mA in a
few cases), but never a single RCD covering multiple circuits.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
Bill Payer wrote:
I'd say it's making too many unnecessary joints. Do you know where the
ring goes upstairs and back down again? You might well find they are
together. Also if you intend keeping the existing socket positions
upstairs it's making more work.

Well, this is rather the point in doing the job in the first place, ie,
we don't have enough sockets.

I see that - but are you adding to what's already there position wise? If
so you could save some work by using the existing cables - they're likely
longer than needed to the next existing socket so can be cut.

It's a three-bedroomed house with just
one double-socket in each room and a single socket out on the landing,
so doing it the way I originally thought would leave four joints under
the floorboards. Is that too many?

IMHO any unnecessary joints should be avoided.

--
*The closest I ever got to a 4.0 in school was my blood alcohol content*

Dave Plowman London SW
To e-mail, change noise into sound.

Andrew Gabriel wrote:
In article ,
Tim W writes:

I'm putting 4 rings in my house. 1.5 for the kitchen/diner (the other 0.5
serves utility and one bedroom), one for the rest of the ground floor and
one upstairs. It's not necessarily the case that the loads demand it, but
it's geographically convenient and povides sensible seggregation in the
event of one circuit tripping (ie I don't lose the whole house).

Last couple of kitchens I've done (16th Ed regs), I put two rings
into each, one RCD protected for the accessible socket outlets,
and one non-RCD protected for stationary/fixed appliances such as
fridge, freezer, oven, boiler, etc, which you don't want sharing
an RCD with anything else, and don't merit one themselves.

Do the fixed appliances merit a ring? They'd be quite happy on a 20
amp radial wouldn't they? I suppose it depends on whether there's
heating involved (washing machine, dishwasher, cooker). In our case
only one of those is in the kithechen though.

Thus far, I always used 30mA RCBO's per circuit (or 10mA in a
few cases), but never a single RCD covering multiple circuits.

--
Chris Green

wibbled on Monday 19 October 2009 19:41

Do the fixed appliances merit a ring? They'd be quite happy on a 20
amp radial wouldn't they? I suppose it depends on whether there's
heating involved (washing machine, dishwasher, cooker). In our case
only one of those is in the kithechen though.

I considered using radials, but it's harder to work with 32A radials (cable
may need to be 6mm2 depending on installation methods and you can't really
get 2 6mm2 cables into one accessory).

20A radials might be fine for normal rooms, but in the kitchen/utility I
have:

1 combi microwave
1 Kettle
1 washing machine
1 dishwasher
1 tumble dryer

A lot of those are right next to sockets so it was easier to run a couple of
rings rather than try to second guess how 20A circuits might be arranged.

20A doesn't really map, especially as some of those can be plugged in to
random places. 32A worked much better, so I chose a ring as the most
practical implementation of a 32A circuit.

--
Tim Watts

This space intentionally left blank...

Tim W wrote:

the new Hager Ashley maintenance free junction boxes:

http://www.tlc-direct.co.uk/Products/ASJ803.html

You've mentioned those before, but I wonder, just because the
manufacturer declares the maintenance free, does that carry any weight
what so ever, would they be accepted by a BCO as not needing access?

I thought I'd seen various people slagging off similar sprung contacts
which are a bit more common on European fittings?

On Oct 19, 1:21*pm, Jim wrote:
NT wrote:
Its entirely pointless, unless of course you run a lot of large loads
upstairs, for reasons I cant imagine.

Splitting the ring into 2x 20A circuits doesn't gain you anything
much, and only worsens its safety performance.

The only place your average 2 bed house would benefit from a 2nd ring
is the kitchen, where the heavy loads live. But even then, as you
already know, in practice one can run a whole house on a single ring.

We've got a similar problem in that we have solid floors downstairs so
all of the ring mains will need to run in the suspended ceilings. The
trouble being that there is a 50m cable length limit on the ring main,
and you use up about 4.5m each socket coming down from the ceiling then
back up.

Unfortunately the windows come too low down on the wall to run across
underneath them, and there are doors/chimney breasts to get in the way
as well.

I was thinking it might be possible to run a thick cable out to some
kind of junction box, then spurs out to each socket rather than a ring -
I don't know if that's allowed under the wiring regs?

It sounds like a sensible approach, as long as you treat the circuit
as a radial. You cant treat it as a ring because you'd have more spurs
than socktes in the ring. You'll need to check your circuit protection
is upto the job, so you might be limited to 20A circuits. But if
you're running a new cable there's little extra in running 2 or 3.


NT

On Oct 19, 2:14*pm, Tim W wrote:
NT
* wibbled on Monday 19 October 2009 13:14
On Oct 19, 12:07*pm, "Bill Payer" wrote:

Our house was built around the early to mid 60s (so has "modern" PVC twin
& earth cabling) and has just one ring main feeding the whole house. We
want to add in some extra sockets but obviously I don't want to overload
the one circuit so I've had an idea that I want to run past you peeps
here.

Most family/friends houses seem to be wired with an upstairs ring and a
downstairs ring. My idea is to go to all the sockets in the upstairs
rooms and basically pull the cables out of the sockets, back down to
under the floorboards and joint them there (either with "traditional"
junction boxes or with crimps/heatshrink sleeve), so that the continuity
of the ring is preserved but it is now just serving the downstairs
sockets, then run a new ring for the upstairs sockets, and adding new
sockets to each ring where needed.

Is this OK?

TIA,
Bill

Its entirely pointless, unless of course you run a lot of large loads
upstairs, for reasons I cant imagine.

Splitting the ring into 2x 20A circuits doesn't gain you anything
much, and only worsens its safety performance.

The only place your average 2 bed house would benefit from a 2nd ring
is the kitchen, where the heavy loads live. But even then, as you
already know, in practice one can run a whole house on a single ring.

NT

I'm putting 4 rings in my house. 1.5 for the kitchen/diner (the other 0.5
serves utility and one bedroom), one for the rest of the ground floor and
one upstairs. It's not necessarily the case that the loads demand it, but
it's geographically convenient and povides sensible seggregation in the
event of one circuit tripping (ie I don't lose the whole house).


Sounds like good practice. Retrofitting such an arrangement isn't
needed though.


NT

Andy Burns
wibbled on Monday 19 October 2009 20:27

Tim W wrote:

the new Hager Ashley maintenance free junction boxes:

http://www.tlc-direct.co.uk/Products/ASJ803.html

You've mentioned those before, but I wonder, just because the
manufacturer declares the maintenance free, does that carry any weight
what so ever, would they be accepted by a BCO as not needing access?

I thought I'd seen various people slagging off similar sprung contacts
which are a bit more common on European fittings?

In the absence of any standard benchmark or test (eg a BS document or
equivalent), I would tend to believe manufacturers who generally
demonstrate competence.

It will also be very rare to find a BCO who wants to argue the merits of
BS7671 minutae, though his agents might...

On the other hand, I've bought stuff with screw terminals where it is near
impossible to get a decent clamp force on the core before the screw strips,
or the core disappears up the side of the screw, so you can do well adn do
badly in both camps.

Cheers

Tim
--
Tim Watts

This space intentionally left blank...

On Oct 19, 3:16*pm, "Bill Payer" wrote:
Bill Payer wrote:
Dave Plowman (News) wrote:
In article ,
* Bill Payer wrote:

Our house was built around the early to mid 60s (so has "modern" PVC
twin & earth cabling) and has just one ring main feeding the whole
house. We want to add in some extra sockets but obviously I don't
want to overload the one circuit so I've had an idea that I want to
run past you peeps here.

Most family/friends houses seem to be wired with an upstairs ring
and a downstairs ring. My idea is to go to all the sockets in the
upstairs rooms and basically pull the cables out of the sockets,
back down to under the floorboards and joint them there (either with
"traditional" junction boxes or with crimps/heatshrink sleeve), so
that the continuity of the ring is preserved but it is now just
serving the downstairs sockets, then run a new ring for the upstairs
sockets, and adding new sockets to each ring where needed.

Is this OK?

I'd say it's making too many unnecessary joints. Do you know where
the ring goes upstairs and back down again? You might well find they
are together. Also if you intend keeping the existing socket
positions upstairs it's making more work.

Well, this is rather the point in doing the job in the first place,
ie, we don't have enough sockets. It's a three-bedroomed house with
just one double-socket in each room and a single socket out on the

Doh! That should be one double socket in each BEDroom, not, as you may have
thought, each room of the house - sorry.

landing, so doing it the way I originally thought would leave four
joints under the floorboards. Is that too many?

Other thing is the ECC on older TW&E is smaller than currently. Not
quite sure how that effects radical alteration. But my gut feeling
would be to keep the old ring as short as possible.

TIA,
Bill


Adding more sockets doesnt increase loading on the ring, and you can
add as many as you want to the existing ring. A single ring house is,
as you already know, perfectly workable, but yes adding a 2nd ring
would surely be preferable if its doable. Otherwise its easy side to
pop a breaker by switching too many things on at once, and fusepoppen
becomes possible.

I cant see any mileage in messing about with the bedroom sockets as
you initially suggested, because it doesnt take any significant load
off the ring. Best would be to put new sockets on your new ring or 2 -
wherever they are in the house.

Where you run a new ring to really comes down to budget and what
damage you're willing to inflict on the decor. The most useful place
to split the load would be in the kitchen, and utility room if there
is one, so I'd look to focus my mind on providing a 2nd ring for
there, with a 2nd ring elsewhere being a signifcantly lower priority.

Hopefully the bedroom could be supplied by more sockets from a cable
laid in the loft, wheher from new ring or old.

If you then have 2 rings feeding one room its a good idea to put a
notice on the fusebox stating this, people have a habit of assuming
all sockets in one room are on the same ring otherwise.


NT

In article ,
Tim W writes:
Andrew Gabriel
wibbled on Monday 19 October 2009 13:35

In article ,
Tim W writes:

In principle it sounds fine. Crimps would be an excellent way to joint
the cable provided that you have a proper crimping tool and are happy
with how it's enclosed. Another way, if you are concerned about the
accessibility of the joints is one of the new Hager Ashley maintenance
free junction boxes:

http://www.tlc-direct.co.uk/Products/ASJ803.html

Those have spring contacts and good cable clamps and IME (of the smaller
lighting ones) *very* well made.

In my view, these are unsuitable for inaccessible connections and do
not comply with the regs for this purpose.

Ashley's use of "maintenance free" would appear to mean they provide
no means to perform any maintenance, not that none would be required.
Indeed, with the absence of large surface area gas-tight contacts
which are present in all the proscribed [maintenance free] methods for
inaccessible connections, I would expect a shorter lifetime from this
product than from standard screw terminals, and as such, thoroughly
unsuitable for an inaccessible connection.

Not used one myself though.


Indeed. These things (Ashley in particular) keep getting mentioned on the
IET forums in exactly this context and opinion goes both ways.

Obviously Hager are strongly hinting that they are suitable. all I can do is
quote:

"The screwless push to fit terminals do not relax, and so do not require
inspection." from:

http://www.hager.co.uk/building-auto...tures/6387.htm

It would be interesting to challenge them on the specifics.


You're an engineer and obviously your opinion is worth much and I can see
your argument.

Well, I'm an physicist really.

I've used them in a semi-accessible location (under floorboards), where
there's some flex in use (SELV downlighters, I use high temperature
silicone flex) and they are very good for this (because the contacts are
suitable for solid or flexible and the cable clamps being present).

Providing you can pop out the downlighters and then pull them
back through the holes, that counts as accessible anyway.
That's the standard way to access the transformers too.

I should note that the springs are pretty strong in these. Whether the
springiness can be proven not to decline in time or whether the contact
pressure is sufficient to prevent oxidation of the cable I couldn't
comment.

I don't know what sort of contact they have, but to have enough
pressure to be gas-tight, it would need to be very small, like
back-stabs. That's OK for a 0.5A lampholder, but not a 30A ring
circuit. Otherwise, if it's a large a spring loaded contact (which
won't have the pressure to be gas-tight), the resistance will
increase over time, which means the heat increases over time
(as a second order effect), which usually weakens springs, so the
contact pressure drops, which further increases resistance and
temperature, and you have a classic runaway overheating joint.
That's not a basis for a maintenance free connection, but rather
more a connection on which maintenance is pretty much guaranteed to
be required. Crimping, soldering, or brazing, as required by the
regs, are maintenance free connections. Even screw terminals can
generate the pressure required for a gas-tight connection,
providing the metals used have similar coefficients of expansion
so the contact pressure doesn't change with temperature.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
NT writes:
On Oct 19, 1:21*pm, Jim wrote:

We've got a similar problem in that we have solid floors downstairs so
all of the ring mains will need to run in the suspended ceilings. The
trouble being that there is a 50m cable length limit on the ring main,
and you use up about 4.5m each socket coming down from the ceiling then
back up.

Unfortunately the windows come too low down on the wall to run across
underneath them, and there are doors/chimney breasts to get in the way
as well.

I was thinking it might be possible to run a thick cable out to some
kind of junction box, then spurs out to each socket rather than a ring -
I don't know if that's allowed under the wiring regs?
It sounds like a sensible approach, as long as you treat the circuit
as a radial. You cant treat it as a ring because you'd have more spurs
than socktes in the ring.

That's a guideline only, and not part of the regs.
It comes about because rings normally start with no spurs,
and have spurs added as later additions. When you reach the
point where there is more addition than original, the original
installation clearly no longer meets current requirements.

In the case of designing a system to be laid out that way
from the start, this concern would not apply.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
writes:
On 19 Oct,
(Andrew Gabriel) wrote:

Last couple of kitchens I've done (16th Ed regs), I put two rings
into each, one RCD protected for the accessible socket outlets,
and one non-RCD protected for stationary/fixed appliances such as
fridge, freezer, oven, boiler, etc, which you don't want sharing
an RCD with anything else, and don't merit one themselves.

I made sure my boiler was on an RCD protected supply. I want volts off ASAP
if there is a water leak.

The problem with this is if something else trips the RCD whilst
you are away for a few days, and the house freezes as a result
of having lost its frost protection, then you could have a house
which is substantially written off by a water leak.

If it has an RCD, like the fridge or freezer, it's a bad idea
to share it, and none really merit a dedicated one. Having said
that, I have a boiler on a dedicated 10mA RCBD, but that's because
it's in the bathroom (and I had several spare 10mA RBCOs;-).

Why /do/ they always put the electrics /under/ the water parts in boilers?

The bottom is cooler, and they don't think much about minimising
the cost of repair when designing boilers.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel
wibbled on Monday 19 October 2009 22:25

In article ,
writes:
On 19 Oct,
(Andrew Gabriel) wrote:

Last couple of kitchens I've done (16th Ed regs), I put two rings
into each, one RCD protected for the accessible socket outlets,
and one non-RCD protected for stationary/fixed appliances such as
fridge, freezer, oven, boiler, etc, which you don't want sharing
an RCD with anything else, and don't merit one themselves.

I made sure my boiler was on an RCD protected supply. I want volts off
ASAP if there is a water leak.

The problem with this is if something else trips the RCD whilst
you are away for a few days, and the house freezes as a result
of having lost its frost protection, then you could have a house
which is substantially written off by a water leak.

If it has an RCD, like the fridge or freezer, it's a bad idea
to share it, and none really merit a dedicated one. Having said
that, I have a boiler on a dedicated 10mA RCBD, but that's because
it's in the bathroom (and I had several spare 10mA RBCOs;-).

Why /do/ they always put the electrics /under/ the water parts in
boilers?

The bottom is cooler, and they don't think much about minimising
the cost of repair when designing boilers.


I would have to say Andrew that I've never personally experienced any
nusiance tripping of RCDs and I've lived for years in a flat with a
whole-flat main 30mA RCD. Is it worth making the design more complicated
(especially given the the 17th pretty much requires all circuits to be RCD
protected - or - make onerous demands on the installation of that circuit)
for a comparitively low risk event?

Cheers

Tim

--
Tim Watts

This space intentionally left blank...

In article ,
Tim W wrote:
I would have to say Andrew that I've never personally experienced any
nusiance tripping of RCDs and I've lived for years in a flat with a
whole-flat main 30mA RCD. Is it worth making the design more complicated
(especially given the the 17th pretty much requires all circuits to be
RCD protected - or - make onerous demands on the installation of that
circuit) for a comparitively low risk event?

I haven't either since changing to a split load unit some years ago. There
are only four circuits unprotected - a utility radial in the kitchen, the
cooker, central heating and immersion.

--
*Always remember you're unique, just like everyone else.

Dave Plowman London SW
To e-mail, change noise into sound.

On Oct 19, 10:07*pm, (Andrew Gabriel)
wrote:
In article ,
* * * * NT writes:
On Oct 19, 1:21*pm, Jim wrote:

We've got a similar problem in that we have solid floors downstairs so
all of the ring mains will need to run in the suspended ceilings. The
trouble being that there is a 50m cable length limit on the ring main,
and you use up about 4.5m each socket coming down from the ceiling then
back up.

Unfortunately the windows come too low down on the wall to run across
underneath them, and there are doors/chimney breasts to get in the way
as well.

I was thinking it might be possible to run a thick cable out to some
kind of junction box, then spurs out to each socket rather than a ring -
I don't know if that's allowed under the wiring regs?
It sounds like a sensible approach, as long as you treat the circuit
as a radial. You cant treat it as a ring because you'd have more spurs
than socktes in the ring.

That's a guideline only, and not part of the regs.
It comes about because rings normally start with no spurs,
and have spurs added as later additions. When you reach the
point where there is more addition than original, the original
installation clearly no longer meets current requirements.

I dont know why one would think that.

In the case of designing a system to be laid out that way
from the start, this concern would not apply.

Or why doing it from new is meeting current requirements but an
expanded old ring isnt.


NT

John Rumm wrote:
Jim wrote:
We've got a similar problem in that we have solid floors downstairs so
all of the ring mains will need to run in the suspended ceilings. The
trouble being that there is a 50m cable length limit on the ring main,

Where did you get that figure from?

There is a maximum 100m^2 floor area that should be served by a single
ring.

The actual cable limits will depend on the voltage drop or earth fault
loop impedance of the circuit and the selected cable type (which limit
kicks in first depends on the actual details).

Your typical 2.5mm^2 T&E with 1.5mm^2 CPC with Type B 32A MCB would
allow 106m of cable (table 7.1 OSG 17th edition). Note this is longer
than the 84m previously allowed in the 16th edition due to the extra
voltage drop now permitted for general purpose power circuits.

Thanks, that's very helpful. The 50 metre number came from:

http://diydata.com/planning/ring_main/ring_main.php

"The length of cable used in a ring circuit is limited
to 50 metres for circuits protected by an MCB."

If that number is wrong then that means we have plenty to play with and
there's no sense in coming up with ad-hoc solutions.

John Rumm wrote:
Bill Payer wrote:

Our house was built around the early to mid 60s (so has "modern" PVC
twin & earth cabling) and has just one ring main feeding the whole
house. We want to add in some extra sockets but obviously I don't
want to overload the one circuit so I've had an idea that I want to
run past you peeps here. Most family/friends houses seem to be wired with
an upstairs ring
and a downstairs ring. My idea is to go to all the sockets in the
upstairs rooms and basically pull the cables out of the sockets,
back down to under the floorboards and joint them there (either with
"traditional" junction boxes or with crimps/heatshrink sleeve), so
that the continuity of the ring is preserved but it is now just
serving the downstairs sockets, then run a new ring for the upstairs
sockets, and adding new sockets to each ring where needed.

Is this OK?

Its ok, but probably hard work. A more pragmatic split might be to do
a ring for the front and another for the back of the house (or left
and right), or house and kitchen (or some combination etc). There is
no reason the split *has* to be upstairs / downstairs. Splitting an
existing ring front and back say - would only require you run a couple
of additional "legs" out to the split point, and would leave most
other sockets / cables untouched.

Thanks John, and indeed everyone who contributed to the thread. I've now got
a way forward

Bill