Best Method for CBUS Setup

Just setting up my first CBUS setup and would like advise on which circuit setup is most advised. Live in Australia and yes I'm a sparky.

Method 1
32A C/B in main switchboard
6mm submains to CBUS board
32A c/b in cbus board
10A RCD combos to each unit

Method 2
32A C/B in main switchboard
6mm submains to CBUS board
32A Combo in CBUS board
10A C/B's to each unit

4mm seperate earth run as well obviuosly

Which method is better?
Cost wise doesn't worry me
Also should they actually be 8A C/B's-combos?
For the relays is it better to run seperate C/B's per channel?
Relays will be doing mainly lighting but may include a couple of GPO's which will be run with 16A C/B's

Any advise would be much appreciated.

 

If the main board and the C-Bus board are in the same building, then you don't need the 32A MCB in the C-bus board.

Method 3
XXA C/B in main switchboard (sized based on maximum demand of C-Bus board and cable current carrying capacity after de ratings applied)
XXmm submains to CBUS board (sized based on maximum demand of C-Bus board)
10A RCD combos to each dimmer unit
16A RCD combos to each relay unit (based on loading, but 16A is usually safe for lighting)
2A MCB for each C-bus power supply (allows isolation of loads while retaining C-Bus power)

I would use a RCD/MCB for each dimmer/relay. 10A for dimmers (yes this is OK as 8A is not available). You need to size the relay MCB/RCD based on load (they can handle 10A/channel, this can equate to 120A total theoretically).

Due to cable de ratings I tend to use a 16A RCD/MCB and then two 10A MCB's (6 channels on each). The de ratings come about because I home run all the cables and that puts a lot of cables in the board (others will disagree with this statement).

You don't need a CB per channel on a relay, that is overkill. AS3000 does not call for it and it just costs money in the long run in cabinet space and hardware to be installed, but if you feel that you want it then there is no reason why you cant do it that way.

Why use a 16A CB on a single GPO. These are only rated for 10A and thus a 10A CB is sufficient. If you know the prospective load (such as a table lamp), then you can lower it even further.

My preference is not to put GPO's on relay, but rather use the C-Bus wireless range of plug in modules. This gives ultimate flexibility. The GPO is not stuck on C-Bus should you change your mind and neither is a GPO stuck as a dumb GPO if you change your mind. It adds a little more cost to the project, but you now have wireless as well for future expansion (wireless remotes etc.)

My 2c

Mick

 

Excellent thanls for that Mick

 

Can you please give more information regarding the selection of MCB/RCD for relays/Dimmers... in our installation we have only 10A MCB at the input of the relays... and 20A for Pro series dimmers...

for relays, the selection of input MCB depends on the amount of load its controlling??