The new electric brake trailer laws mean that you need to check if you trailer is legal to tow in NSW.
For trailers with a GTM exceeding 2 tonnes, the braking system must be capable of being applied from the driver’s seat – overrun brakes are not acceptable. In addition, the braking system must be such that if the trailer accidentally breaks away (from the towing vehicle), the trailer brakes will apply automatically and remain applied for at least 15 minutes.
It should be noted that the brakes must operate on ALL WHEELS (exceptions are trailers not over 2 tonnes Aggregate Trailer Mass (ATM) and trailers manufactured prior to ADR 38/–. Their service brakes must operate on all wheels on at least one axle).
The towing vehicle is equipped with an electrical circuit which will automatically maintain the trailer battery in a fully charged condition and is capable of warning the driver if the condition of the trailer battery is such that it may not be capable of meeting the requirements.
Which means you need a battery monitor on the dashboard of your vehicle and compatible breakaway unit.
For the full law click the link to the PDF