Re: Re: Lighting Control (was Re: Adverts)

[Nigel Orr <Nigel.Orr@xxxxxxx>]

-------------------------- eGroups Sponsor -------------------------~-~>
GET A NEXTCARD VISA, in 30 seconds!  Get rates
of 2.9% Intro or 9.9% Ongoing APR* and no annual fee!
Apply NOW!
http://click.egroups.com/1/7872/9/_/2065/_/967648089/
---------------------------------------------------------------------_->

At 15:09 30/08/00 +0100, you wrote:
>This is what I was thinking of - originally, I wanted a cat5 to every
>rose, but the electrician said it contravened IEE regs.

Hmmm, I think there might have been a misunderstanding there.  It would
have to be suitably isolated from the mains wiring, which would be tricky
in a standard ceiling rose, but not impossible, and it definitely should
not be directly or indirectly connected to the mains (eg through anything
apart from an air gap, a suitable transformer, or optoisolator- resistive
or semiconductor barriers aren't sufficient).

Aside from that, I'm not aware of any IEE reg about it- it's not that
different to the cables going into the back of a mains powered hi-fi or PC,
though it's in a smaller space.  I have UTP cables from Comfort to the
DIN-rail mounted relays I've mentioned earlier, but using IR for lights
does seem to have some other advantages as well as isolation.

But if he wasn't sure about it, it's better to say it's not possible than
to just go ahead and do it.  Better still would be to go away and research
what was possible but that is probably too much to reasonably expect.  The
average electrician will do things the way they've always done them, maybe
change them after new regs have been out for a while and have filtered
through, and claim that anything else 'is against IEE regs'.

You can either tell them you'll accept full responsibility for any damages
caused by that part of the wiring or be snotty about it, plonk a copy of
BS7671 down in front of them and say "show me".  The first
approach is
generally more successful, I believe- I've not tried the second and don't
intend to :-)  If they run the cables but leave them outside the ceiling
rose, and make clear to you that they should stay outside the ceiling rose
and away from mains voltages, they shouldn't be at any risk of you suing
them when you burn the house down or electrocute the postman...

>  I'm currently
>considering the LD10/LD11 in the rose method.

IIRC, you'll need a 4" diameter rose, a bit deeper and wider than a
standard (3") one.  It shouldn't look much bigger, but I've not seen
them
available commercially.  I was considering having some custom made, but
there wasn't enough interest to make it worthwhile (most of the cost is in
setting up the mould)- AIUI lots of people don't have ceiling roses (I
presume because they have LV halogen lighting or other built-in lights)

Another alternative might be to mount the LD10 in the ceiling from below,
with a standard rose covering it, but it would be fiddly for ground floor
lights if you can't lift upstairs floorboards.

> I'd wondered using 418 MHz radio links to do this stuff - but I'm
>concerned about TETRA taking over the frequencies.

In brief summary, don't use 418 for new designs, 433 is still in current
use but might be reallocated eventually, there are modules for 868MHz and
173MHz, and various other bands, available too.  Basically, a 433MHz system
with a decent receiver shouldn't get upset by TETRA, at least for 5 or 10
years.  Hopefully...

Having used RF and IR for various things, my current preference is for IR
(or cable  if at all possible!) for a stable reliable system- RF can be
very variable, and construction is more critical than 38kHz +/- 5%
infrared.  But it is an educational experience, no harm in trying it for
yourself!  I made a wireless doorbell, a simple serial link with a PIC and
a module from http://www.rfsolutions.co.uk at
each end, and it was fun to
do.  It's now been replaced by a length of UTP...

Nigel