I'm in the final throes of bringing the house into the modern era and
in terms of electrics all that remains is updating our living room and
dining room sockets.

The current sockets in the l/room and d/room (all three of them) are
on a radial circuit, with the cable from the CU looking to be about 4
or 6mm.

Currently the cable runs from the CU in a cupboard, through a pipe
under a solid (ornately tiled) hall floor emerging under the suspended
floor in the dining room. The length is approximately 3.5 - 4 meters
to that point.

When fitting upstairs I installed a new ring and led the ends back to
the CU. A spark came along and tested the new cicuit before
connecting it up, thus saving me lots of money on donkey work (lifting
floorboards, chasing brick etc.)

If I were to do the same downstairs I seem to have three options:
1) Stick with a radial circuit and use the perfectly good chunky wire
that's already there. This will require SWK to help with the maths so
I know how many sockets I can install.

2) Ignore current radial and run new ring, travelling through the
ceiling void crossing the whole house, before coming down an exisiting
service duct into l/room then run as ring like normal. Downsides are
that this uses a lot more cable.

3) Extended upstairs ring to include downstairs so that all sockets
are on one ring. Again this would need careful calculation to make
sure I'm not exceeding limits on potential load and cable length.

4) Combined ring/radial. Does such a concept exist? Have I entirely
missed the point? Is there any merit in attaching a junction box to
the old radial cable where it enters the under floor void in the
d/room and then running a ring of 2.5mm cable around downstairs?
Presumably the limiting factor is the size of the existing length of
radial? Obviously you use much less 2.5mm cable and don't have to
cross the span on the house through the celining void. You keep two
seperate circuits for upstairs and downstairs.

I may be able to squeeze a bigger individual cable through the
underfloor pipe but I wont be able to fit two 2.5mm.

I'm undecided and don't have enough experience to make an educated
decision. The simplest thing is to run a new ring across the house.
The next simplest (but less cheap) option is to just ask Mr Spark to
do it. I don't know what the BEST solution is.

Any help gratefully received.


--
Steve F

"Fitz" wrote in message
om...
I'm in the final throes of bringing the house into the modern era and
in terms of electrics all that remains is updating our living room and
dining room sockets.

The current sockets in the l/room and d/room (all three of them) are
on a radial circuit, with the cable from the CU looking to be about 4
or 6mm.

Currently the cable runs from the CU in a cupboard, through a pipe
under a solid (ornately tiled) hall floor emerging under the suspended
floor in the dining room. The length is approximately 3.5 - 4 meters
to that point.

When fitting upstairs I installed a new ring and led the ends back to
the CU. A spark came along and tested the new cicuit before
connecting it up, thus saving me lots of money on donkey work (lifting
floorboards, chasing brick etc.)

If I were to do the same downstairs I seem to have three options:
1) Stick with a radial circuit and use the perfectly good chunky wire
that's already there. This will require SWK to help with the maths so
I know how many sockets I can install.

2) Ignore current radial and run new ring, travelling through the
ceiling void crossing the whole house, before coming down an exisiting
service duct into l/room then run as ring like normal. Downsides are
that this uses a lot more cable.

3) Extended upstairs ring to include downstairs so that all sockets
are on one ring. Again this would need careful calculation to make
sure I'm not exceeding limits on potential load and cable length.

4) Combined ring/radial. Does such a concept exist? Have I entirely
missed the point? Is there any merit in attaching a junction box to
the old radial cable where it enters the under floor void in the
d/room and then running a ring of 2.5mm cable around downstairs?
Presumably the limiting factor is the size of the existing length of
radial? Obviously you use much less 2.5mm cable and don't have to
cross the span on the house through the celining void. You keep two
seperate circuits for upstairs and downstairs.

I may be able to squeeze a bigger individual cable through the
underfloor pipe but I wont be able to fit two 2.5mm.

I'm undecided and don't have enough experience to make an educated
decision. The simplest thing is to run a new ring across the house.
The next simplest (but less cheap) option is to just ask Mr Spark to
do it. I don't know what the BEST solution is.

Any help gratefully received.



Steve F

Regarding the size of the existing radial cable if as you suggest it may
already be 6mm and you think that you could squeeze a bigger size 10mm?
through then logic suggests that 2 x 2.5 should go through easily

You do not say how the kitchen is wired. Is this on a ring of its own? how
many sockets on it?
It may be that you could extend this ring for the rest of the downstairs.

With 2.5 t&e only £19.00 100metres why not replace the existing radial cable
with a new length of 2.5mm as one leg of the ring and run the the return leg
of the ring through the service duct and ceiling void?
You would then have a proper ring with all new cable but only one long leg
and you could then significantly increase the number of sockets in the
lounge/dining room should you wish to do so

HTH

Tony

On Tue, 27 Jul 2004 17:15:46 UTC, (Fitz)
wrote:

The current sockets in the l/room and d/room (all three of them) are
on a radial circuit, with the cable from the CU looking to be about 4
or 6mm.

Currently the cable runs from the CU in a cupboard, through a pipe
under a solid (ornately tiled) hall floor emerging under the suspended
floor in the dining room. The length is approximately 3.5 - 4 meters
to that point.

Is there any possibility of joining the ends of the two radials
together? Then you could take the CU ends to the same point in the CU
and have a ring. Use the right MCB for a ring and you can use 2.5T+E for
the extra bit.
--
Bob Eager
begin a new life...dump Windows!

I'm in the final throes of bringing the house into the modern era and
in terms of electrics all that remains is updating our living room and
dining room sockets.

Use the current cable. Add as many sockets as you like to it. Keep it as a
radial. If it is 6mm cable, use a 32A breaker. If it is 4mm, you may need to
do some calculation to see if you can use a 32A or only a 20A breaker.
However, you're extremely unlikely to need more than 20A for two reception
rooms anyway. There's no need to upgrade to a ring. Things are different if
it powers more than the 2 rooms, especially if it involves kitchens.

Unless, of course, the old cable isn't PVC, but rubber or something else
awful (aluminium springs to mind).

Christian.

On 27 Jul 2004 10:15:46 -0700, (Fitz)
strung together this:

If I were to do the same downstairs I seem to have three options:
1) Stick with a radial circuit and use the perfectly good chunky wire
that's already there. This will require SWK to help with the maths so
I know how many sockets I can install.

No maths needed. A 20A radial, (probably what's already ther as that's
most common), can supply 50m^2 of floor area, a 32A ring main can
supply 100m^2

2) Ignore current radial and run new ring, travelling through the
ceiling void crossing the whole house, before coming down an exisiting
service duct into l/room then run as ring like normal. Downsides are
that this uses a lot more cable.

I'd do this, the extra cable isn't going to cost a fortune and won't
cause any problems.

3) Extended upstairs ring to include downstairs so that all sockets
are on one ring. Again this would need careful calculation to make
sure I'm not exceeding limits on potential load and cable length.

In a domestic installation load and cable lemgth calculations are
unneccesary unless you live in a huge mansion type property. Only
golden rule is one ring circuit shouldn't supply more than 100m^2 of
floor area.

4) Combined ring/radial. Does such a concept exist?

Not conventionally but if you could get a 6mm^2 cable through the
existing ducting, then you could place a junction box where the cable
enters the underfloor void and run a conventional ring with 2.5mm
cable. Might be worth running that one by whoever you're getting to
test the work after though as some people would be confused by an
unusual concept and just condemn it.

Is there any merit in attaching a junction box to
the old radial cable where it enters the under floor void in the
d/room and then running a ring of 2.5mm cable around downstairs?

No, you wouldn't be increasing any circuit capacity as the limiting
factor would be your run to the mains, so you may as well just rewire
the existing sockets, and add new ones, on a radial circuit.
--

SJW
A.C.S. Ltd