"John White" wrote in message
...
JupiterJon wrote:

As I need to rewire my new house I thought I'd take the opportunity to
add
some home automation ... however there are so many options and all the
good
ones (star network with DIN based switching) seem too expensive for me
just
now. So how difficult is it to convert from ring to star?

It's tricky to convert power circuits properly. Also most of the
systems I have seen or installed control very few socket outlets
directly. You will almost certainly still need a number of
uncontrolled sockets to plug in such things as a vacuum cleaner.

Where appliances are to be switched in this way it's much better to
wire them using radial (star) circuits in the first place. You can
initially connect them into appropriate MCBs at the consumer unit and
add any control units later.

This allows you to wire the ring circuit in the usual way and to make
all the usual load calculations.

Would it be possible to:
-Run the ring to sockets and switches in conduit through plaster
initially
If / when budget, time etc allow use of c-bus or similar

Switches are not normally on a ring. You will also find that conduit
does not fit in the depth of most plaster - so be prepared to dig into
the walls as well.

For a socket
-draw-out ring cable from conduit leading to socket
-use a junction box in under floor cavity to make ring continuous
-drop star-cable into socket

Yes. However if such sockets were wired as radials anyway then you
would only need to add a control unit at an appropriate place.

For a light
- using existing ceiling rose / junction box in under floor cavity to
continue light ring
- connect light fitting to star-wired DIN-Dimmer
- draw-out live/switched live cable to switch from conduit
- drop in c-bus control cable to switch box

Why not run the cable for the light fitting and light switch to where
you eventually intend to locate the DIN system boxes. You can then
make all the connections there and it will save you pulling up the
floor later.

I understand that in the recent regulations junction boxes are frowned
on,
but they must be used for lighting circuits and if running a garage
circuit
from a consumer unit (or are you expected to run SWA cable through the
house
too). So if these are acceptable is the above use of junction boxes
OK???

I don't know who told you this but they are wrong.

Junction boxes can be used anywhere as long as they are appropriately
rated, and the connections made correctly.

SWA cable does not fit into junction boxes in any case.

John
--
John White,
Electrical Contractor

Wire as star originally and then add controls - that is an excellent and
simple solution Not sure why I didn't think of that :-s
The hurdle now is to work out which sockets should be star-wired.
For sockets I am thinking 1 socket near curtains for automated opening, 1
for AV equipment that would sit on standby. And more for lights.

Thanks
Jon