Re: HA without fallback-CBUS

[Chris Hunter <cjhunter@xxxxxxxxxxxx>]

Um ... SWMBO ... how about training her up, instead ?

Chris



Martin McCreesh wrote:

> Thanks for all the responses..
>
> Probably should have been a bit clearer in first message.
> 1) Override on key circuits is essential for SWMBO approval of CBUS
> whole house install. Doesn't matter what the rest of us think is
> needed!!!   In fairness I do travel for work quite a bit and
> hardwiring etc not really an option in event of failure. Also I only
> have 2 dimmers and there is one at each node so cant really share
> loads from different areas on each dimmer unless I go back to single
> node. If a dimmer blows the CBUS local or remote override is useless
> anyway.
>
> 2) As Neil said I only plan to put the switches at the CBUS nodes
> which are in two storage presses, however while the panels ideally
> would be mounted at ceiling height had hoped to put the switches at
> normal height inside the cupboard - I guess no reason why I couldnt
> put the panels lower and mount the swicthes in the panel. Are there
> DIN mounted two way switches available?
>
> 3) Because I could not be sure that curious hands wouldn't flick the
> switch without isolating the circuit first I think two way is the only
> save bet as somebody else described. Trouble is it means that
> different circuits will have different wiring paths whereas if I was
> sure that CBUS could deal with the back feed the wiring would be
> simple and could be added after the installation on the key circuits.
>
> Thanks again,
> Martin
>
>   ----- Original Message -----
>   From: Neil Fuller
>   To: ukha_d@xxxxxxx
>   Sent: Saturday, January 14, 2006 9:57 AM
>   Subject: Re: [ukha_d] HA without fallback-CBUS
>
>
>   Just a few thoughts . . . .
>
>   I think Martins suggestion of manual over ride switches for critical
>   circuits is an excellent idea. However, I wouldn't put the switches
on
>   the wall (I don't think Martin was suggesting this anyway?).
>
>   Rather, I would put the switches on the panel the CBUS units are
housed
>   in, assuming that they are reasonably accessible. By doing that,
there
>   is minimal extra wiring and there would never be a situation where a
>   CBUS dimmer would be "back-fed"
>
>   I deal with BMS every day and Nigel is quite right that BMS
>   manufacturers do not recommend adding HOA switches to over-ride
their
>   equipment. That would be tantamount to the manufacturer admitting
that
>   their equipment is less than perfect and may, one day, break down
;-)
>
>   However, I seldom come across an HVAC MCC panel that is not equipped
>   with HOA switches, which are normally specced by the consultant.
Whilst
>   retrofit lighting systems will often be without HOA switches, I have
>   seen many new installs that do have over ride switches for fittings
at
>   key locations. Largely it seems to depend on the  installed
>   infrastructure. If the dimmers etc are centrally located, over ride
>   switches are easy to provide. If however the controllers are
>   distributed, and above ceilings, it's rare to see  HOA switches.
>
>   Of course, emergency fittings will overcome mains failures etc and
need
>   to be sited to provide illumination of key escape routes. Nigel,
have
>   you installed a centralised emergency lighting system or used
separate
>   luminaires? In my experience, the centralised systems , with their
far
>   more reliable lead-acid battery stacks are much preferred over the
>   distributed systems, although of course the wiring has to be in pyro
> and
>   so starts to get costly (and I guess a large stack of batteries is
>   overkill for an average house).
>
>   Regards
>
>   Neil
>
>   Nigel Giddings wrote:
>
>   >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
> <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]
>   >
>   >
>   >
>   >
>   >
>   >
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>   >14/1/2006
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