Cabling from Meter box to C-bus distribution cabinet

Hi Ian
Unless you are breaking the gauge of the cable and installing circuit breakers for the protection of the cables, it would not be a sub board.
In Australia anyway.
From your post saying you have 1amp circuit breakers on the C-Bus outputs, I guess you must be somewhere in the UK. Why don't you stick that in your profile, It helps folks give you an appropriate response as the rules differ per country.
Go to the "User CP" tab, click "edit your details" and you should see a place to stick your location at the top of the page.

 

Hi,
I am a new user and have just completed a CBUS basic course.

I am in the process of installing cbus to my existing house. I have decide to rewire it as the old wiring was not in good shape. I have attached a pdf of what i plan on doing from the 240V side and would like some advise.

Do i need to protect the individual outgoing circuits or is it enough i just protect the supply to each module?

Could i please only have responses from Australia manily due to the different rules and regs
Regards

Ozsparky

 

go for it

H Ozsparky
Your diagram is about what you want to do. If you are going to connect an individual c-bus module to it's own CB/RCD/MCB, then you may not need 2.5Tw+E or a 20A CB. I find it much easier to work with 1.5mmTw+E in the boards, especially if you may have the need to install 2 wires into one C-Bus terminal, there is not much room in them.

Personally I have 1 x 10A RCD for all upstairs lights on 3 x C-Bus dimmer/relays and 1 x 10A RCD for all downstairs lights controlled by 4 x C-Bus dimmer/relays. There are a few other external loads (path lights & pool pump) on another RCD controlled (switched) by one of the downstairs relays and they are in 2.5mmTw+E due to the long run outside. EDIT: And the fact I am switching a Socket outlet (GPO) supply!!

Cheers, hope that helps.

 

Hi Mathew,

Thanks for the promt reply. I can understand using 1.0mm2 or 1.5mm2 for the lighting,fans,and other directly connected devices such as blinds shutters which would have gpo's with round earth pins. But isn't it a requirement of AS3000 table 8 that gpo's should be wired in 2.5 as a minimum? anything smaller is NP Not Permitted.

So if i was controlling gpo's that supplied say tv's, projector, even desk lamps I would have to run them in 2.5mm2 unless i made the all gpo's with round earth pins.

 

is a GPO a GPO when it has a round earth pin?

I believe it is not. If the outlet is installed for a specific purpose and its location is such that it cant be easily used for other devices then it is not a general Purpose outlet, but rather a specific purpose outlet and hence is exempt from that statement (so an outlet for motorised blinds would not be a GPO).

There is also a clause (unless it has been removed since I last read the standard) saying that an outlet above a certain height is also exempt.

Same for "GPO" used for light fittings and fans in the ceiling. These are not GPO's and hence 1.5mm is acceptable

Just my understanding

Mick

 

comply with the rules...

Hi Ozsparky
Yes you are correct, if you are switching Socket Outlets (GPO's) they should be in 2.5mmTw+E as to standard practice & original long standing rules. However if you look at clause 3.5.1 & table 3.3 of the rules, exception 1 says you can use smaller conductors if you deem it suitable.

 

Thanks Znelbok and Mathew.

I had a similar interpretation of the rules as well. I will stick to what i know and run 2.5mm2 for all power outlets and 1.0mm2 or 1.5mm2 for all lighting,fans,blinds (depending on load requirements) etc.

The main concern is that in the future if i sell the place someone could come along and plug an electric heater or two into one of the controlled circuits (asuming they were standard GPOs) and trip the breaker.



rergards

Ozsparky

 

Hey gents, I know this an old post but it would be good to clear this up so people don't use this as a guide for domestic installs. Firstly you need to know what each relay is doing (lighting, power or mixed circuit) and have a base-line for cable sizes from there. Clipsal have ratings for Voltage Free Relays depending on their intention. Electricians in Australia need to use a minimum of 2.5mm 2C&E for all GPO's with the exception of some fans and equipment that can be classed as lighting (see max demand in AS/NZS3000). If the circuit is a mixed circuit (power and lighting), it must still use 2.5mm 2C&E as a minimum. Lighting circuits CAN use 1.5mm or even 1mm (in some cases) but for the cost of cabling these days, stick with 2.5mm I find will always be a safe bet compared to cost. Always keep in mind voltage drop and other factors in your AS/NZS3008 and AS/NZS3000 (Australian Standards).