RE: HA without fallback-CBUS

["Nigel Giddings" <nigel@xxxxxxxxxxxxxx>]

Martin,

It is my understanding that C-Bus is used in many commercial
applications, including the new Wembley stadium...

I don't know of any instructions supplied by C-Bus or any other BMS
manufacturer which suggests that 'back-up' switches are required in case
of failure...

I am also not aware of any safety regulations for commercial buildings
which say that lighting must have mechanical switches, as opposed to
electronic ones, for safety reasons. Of course emergency lighting will
be part of the design but not linked into dimmer failure...

The MTBF (Mean Time Before Failure) of a C-Bus dimmer, I hope, probably
exceeds a standard wall mounted dimmer. A total failure of C-Bus is
unlikely to occur unless you rely on a single Bus power supply which I
would suggest is bad design. C-Bus relies on a distributed design.

I will have a number of self contained emergency lights (5) to cover
mains failure or MCB trip but I don't intend to have over-ride
mechanical switches. Worst case, your dimmer fails, you identify the
problem you hard wire the light on till a replacement dimmer is
installed...

I am also using a Midon Temp05/Homeseer system to operate my central
Heating in my existing house(the automation was retro-fitted) and I did
install changeover switches to enable the existing mechanical switches
to act as a back up, in 3 years I've never used them. I will use a
similar system in the new house, still being built, but will have a much
simpler override as the new house has 11 heating zones. I will probably
revert to a single centrally located mechanical thermostat in case of
computer failure...

HTH

Nigel

-----Original Message-----
From: Martin McCreesh [mailto:martin@xxxxxxx]
Sent: 13 January 2006 21:48
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] HA without fallback-CBUS

I've been looking a half way approach for a cbus install later this
year. Planning to put override switches for main lights at 2 key
locations in the house. These locations will be CBUS nodes anyway.  One
issue that maybe somebody can help with is what happens if you apply
full power to a cbus dimmed circuit - could it damage the CBUS dimmer.
The alternative requires a good bit of extra cabling and invloves using
a two way switch to isolate the feed to the light from CBUS.

----- Original Message -----
From: David Gumbrell
To: ukha_d@xxxxxxx
Sent: Friday, January 13, 2006 8:28 PM
Subject: Re: [ukha_d] HA without fallback


Depends what you mean by a fallback. My Idratek

install<http://www.automatedhome.co.uk/modules.php?name=Forums&file=view
topic&t=746>is
designed to be i) removable in case of sale and ii) tolerant to
control
computer failure due to Reflex (built-in) functionality. If there's no
power
to the HA network, there's probably nothing to switch !

I know of another Idratek install which has put the panel relays in
parallel
with existing switching, which might be the kind of fallback you were
thinking of. I guess that you could do something similar with the
other
systems (C-Bus etc) out there.

But really, anyone would think you can't trust this technology stuff
... :-)

Dave


On 1/8/06, Mal Lansell <mal@xxxxxxx> wrote:
>
> I thought most people did go the whole hog - wiring for mechanical
> switches and for HA is mutually exclusive in most situations.
>
> So, wire it up, and buy a torch ;-)
>
> Mal
>
>
> Chris Hunter wrote:
>
> >'wondered if anyone had been brave enough to go for HA without teh
> >fallback - ie: without manual switches on the lighting circuits,
without
> >manual timeclocks & thermostats, and so-on ... might save a
good
part of
> >the costto go the whole hog ! ... less wiring included ... ?
> >
> >Chris
> >


[Non-text portions of this message have been removed]