I notice from the central heating diagrams that 4 (and sometimes 5)
connections need to be made between the junction box and the programmer.
Is there a particular cable for this or is it usually knocked up with a
couple of runs of twin and earth?

Thanks

Paul

In article ,
Paul Roman writes:
I notice from the central heating diagrams that 4 (and sometimes 5)
connections need to be made between the junction box and the programmer.
Is there a particular cable for this or is it usually knocked up with a
couple of runs of twin and earth?

IME, it's usually done with a couple of runs of twin or triple and
earth. I needed 7 core for mine, and after a long hunt, I found a
small electronics shop in Luton which sold 7 core suitable for
mains use (H05RR-F7, IIRC) by the metre. Recently went back to get
some more and they've closed down - bugger.

--
Andrew Gabriel

I notice from the central heating diagrams that 4 (and sometimes 5)
connections need to be made between the junction box and the programmer.
Is there a particular cable for this or is it usually knocked up with a
couple of runs of twin and earth?

I've normally seen multiple cables. Frequently, it has been a 2+E for the
permanent live and 3+E for signalling/switched lives. Not that I've seen
that many installations.

Christian.

"Paul Roman" wrote in message
...
I notice from the central heating diagrams that 4 (and sometimes 5)
connections need to be made between the junction box and the programmer.
Is there a particular cable for this or is it usually knocked up with a
couple of runs of twin and earth?

Thanks

Paul
Mine (fitted by an electrician) uses a special cable/flex which has lots of
different coloured wires.
HTH
Dave R

In article ,
Paul Roman wrote:
I notice from the central heating diagrams that 4 (and sometimes 5)
connections need to be made between the junction box and the programmer.
Is there a particular cable for this or is it usually knocked up with a
couple of runs of twin and earth?

If it was situated so you could use flex, then a wholesaler will do
multicore flex. Think Maplin do too. But if it's situated some way off,
then suitably marked TW&E will be fine. Or Triple & E as used on two way
lighting.

--
*Nostalgia isn't what is used to be.

Dave Plowman London SW 12
RIP Acorn

Paul Roman wrote:
I notice from the central heating diagrams that 4 (and sometimes 5)
connections need to be made between the junction box and the
programmer. Is there a particular cable for this or is it usually
knocked up with a couple of runs of twin and earth?

They make a special multi-way cable for the job. The wires are quite small
so overall the cable size is similar to say a kettle flex. I bought mine in
a larger B&Q. I think they call it "central heating control cable"
You can use T&Es but its way overkill for the currents involved and too
bulky esp behind the programmer.

"Paul Roman" wrote in message
...

I notice from the central heating diagrams that 4 (and sometimes 5)
connections need to be made between the junction box and the programmer.
Is there a particular cable for this or is it usually knocked up with a
couple of runs of twin and earth?

Multi core flex cables are easy to come by. I recall seeing some in B&Q.


---
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Is there a particular cable for this or is it usually knocked up with a
couple of runs of twin and earth?

I've noticed you can get 5 core HiTuf fairly easily.

Christian.

In article ,
Andrew Gabriel wrote:
IME, it's usually done with a couple of runs of twin or triple and
earth. I needed 7 core for mine, and after a long hunt, I found a
small electronics shop in Luton which sold 7 core suitable for
mains use (H05RR-F7, IIRC) by the metre. Recently went back to get
some more and they've closed down - bugger.

Assuming it's carrying mains, what do the regs say about treating flex as
permanent wiring in terms of long runs within a house?

--
*Money isn't everything, but it sure keeps the kids in touch.

Dave Plowman London SW 12
RIP Acorn

"Paul Roman" wrote in message
...
I notice from the central heating diagrams that 4 (and sometimes 5)
connections need to be made between the junction box and the programmer.
Is there a particular cable for this or is it usually knocked up with a
couple of runs of twin and earth?

Thanks

Paul

There are many multicore flex and cable manufacturers and many different
styles of to choose from. This particular one will take mains voltage up to
a maximum of 10 Amps which is more than enough for a central heating control
panel or timer / programmer installation.

http://tinyurl.com/lmv7

Dave Plowman wrote in message ...

Assuming it's carrying mains, what do the regs say about treating
flex as permanent wiring in terms of long runs within a house?

Use of flexible cables and cords is not ruled out provided all the usual
relevant requirements are met [521-01-04]. IMO though, it's inappropriate
for normal fixed power & lighting wiring where more suitable cables are
readily available. For multi-core control wiring (like CH controls) it's
quite OK.

Minimum (copper) conductor sizes for all types of cable are defined [Table
52C]:

- 1.0 mm^2 for power & lighting circuits

- 0.5 mm^2 for signalling & control circuits

- 0.1 mm^2 for signalling & control cables with 7 or more conductors
intended for electronic equipment.

(All conductors must be adequately protected against overheating caused by
fault (s/c), and where relevant, overload current.)

When using multi-core cables, colour coding must be observed [Table 51B]:

- 1, 2, or 3-core cables to use the usual brown, blue, green/yellow

- 4 or 5 core cables may use either brown or black for phase (live)
(5 cores is not mentioned, but I'd assume the same)

- cables including plain yellow or green cores are not allowed

- cables including any bi-colour combination other than grn/ylw are
not allowed.

--
Andy