In my experience, everyone will tell you that DIY cabling in Australia is illegal, unfortunately that is wrong!
If you are cabling for an "Intranet" with no likelyhood of any outside connection (by any means) then you can go for your life. I was forced to face this fact recently and sought clarification from the ACMA to clear things up. Below is the Email (the names have been changed or omitted to maintain privacy). You will note however that they really try and maintain control by trying to imply that it is likely that any cabling will be connected.
I am not a lawyer and as such I cannot provide you with legal advice. However, all telecommunications customer cabling (i.e. telecommunications cabling on the customers side of a carriers network boundary) must be installed by a registered cabler as mandated by the Telecommunications Cabling Provider Rules 2014 in accord with the requirements of AS/CA S009:2013 Installation requirements for Customer Cabling (Wiring rules) the application of the Wiring rules is quite clear – the Wiring rules state that,
The Standard applies to the installation and maintenance of fixed or concealed cabling or equipment that is connected, or is intended to be connected, to a telecommunications network, including any cord or cordage, or that part of any cord or cordage, that is connected as fixed or concealed cabling.
You should be aware that connection to a telecommunications network is not limited to a direct physical connection, it includes connection by any means including via intermediate item(s) of equipment (which would also include a “private” network that has connectivity to the public network) or even wirelessly (via Wi-Fi or a 2G/3G/4G modem).
If any part, or all, of your customers network connects (directly or otherwise) to any Australian carriers network then the Wiring rules apply – to the entire network.
If no part of your customers network currently connects (directly or otherwise) to any Australian carriers network then the Wiring rules would not notionally apply however, if any part is of your customers network is likely to be connected to any Australian carriers network at any point in the future then the Wiring rules would apply and the entire installation would have to be compliant.
While I note your customer claims that “there is no possibility of connection to a carrier service” realistically this is invariably not the case now-a-days given there are so many ways of connecting to a carriers network.
For example if it is possible to remotely access any part of your customers infrastructure using any Australian carriers networks (i.e. accessing a site from a laptop via the internet – either via a direct or indirect physical connection, via Wi-Fi or a 2G/3G/4G modem etc) then your customers network is connected to a carriers network and would be subject to the Wiring rules.
So basically if you want a network that is completely isolated from the outside world, go for your life1