RE: Re: CBus introductory course

["Rob Mouser" <rmouser@xxxxxxx>]

I think this is one that just can't be answered 'yet'. When installing
cbus for the first time I had many such questions. For example:

Does cbus come under SELV regs?
Can a cbus switch be fitted in a bathroom?

The answers at the time from CIS were ambiguous to say the least.

The reality is it that the regs were written before cbus and thus you
have to 'take a view'. I have had a building inspector check my property
and he gave it the all clear. But what was clear was that he was VERY
unfamiliar with cbus or any such system and took a 'view'.

Over time inspectors and the regs will catch up. As with all
regulations, whether they be H&S, Fire, Building a large amount of it
is
GREY. Not black and white and much comes down to interpretation by your
local building inspector.

If you're at all uncertain, get the building inspector to come and see
you. They are generally very helpful and ALMOST always get quite excited
about seeing something new and shiny in the world of the building trade.

My final comment is perhaps a little more controversial;

If your going for a full blown pro install then fine if not. Consider
the option of installing a traditional 240v circuit for lighting etc
side by side with cbus, you don't have to physically wire it up BUT if
you decide to leave or sell your current property you can restore it to
a 'normal' state and take all your goodies to the next property. Buyers
at certain house price levels are VERY shy of all this 'fandangled'
technology and it may actually inhibit your ability to sell.

Many thanks

Rob Mouser
rmouser@xxxxxxx



-----Original Message-----
From: Paul Robinson [mailto:ukcueman@xxxxxxx]
Sent: 16 June 2003 18:40
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Re: CBus introductory course

Yes, but if your cbus installation does not qualify as SELV, then you
can't
do stuff with it that is limited to SELV, such as installing an SELV
light
switch in your bathroom.

Paul

----- Original Message -----
From: "Keith Doxey" <ukha@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Monday, June 16, 2003 6:18 PM
Subject: RE: [ukha_d] Re: CBus introductory course


> 36V DC would not be a problem as Telephone lines are nominally 50V but
can
> be as high as 70V or 80V for digital lines and Telex.
>
> Power Over Ethernet (POE) is also around 48V. That carried Data and
Power
in
> the same cable.
>
> Keith
>
> www.diyha.co.uk
> www.kat5.tv
>
>
> > -----Original Message-----
> > From: Paul Robinson [mailto:ukcueman@xxxxxxx]
> > Sent: 16 June 2003 16:38
> > To: ukha_d@xxxxxxx
> > Subject: Re: [ukha_d] Re: CBus introductory course
> >
> >
> > Hi Rob,
> >
> > Apart from the qusetion of whether it would work, it was also
> > suggested to
> > me that the regulations require physical separation between
> > cables that
> > carry power from those that don't, even if they only carry
> > DC. For those
> > that are not familiar with this, cbus cat5 carries 15-36V DC to
power
> > devices. So it's possible that laying cbus cat5 next to other
> > cat5 breaches
> > the regs.
> >
> > I don't have a copy of the regs themselves, but I do have a
> > copy of "The
> > electrician's guide to the 16th edition of the IEE wiring
> > regulations" by
> > John Whitfield. Unfortunately, it isn't explicit on this
> > matter. The closest
> > relevant info I can find is that to be considered an SELV
> > system, "there
> > must be physical separation from the conductors of other
> > systems...". So
> > it's possible that an incorrectly installed CBus system does
> > not meet the
> > requirements of an SELV system.
> >
> > I don't know what the consequences of that are, nor whether
> > the regs are
> > really able to cope with this.
> >
> > Paul




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