Your Utility Power distribution system method used in Australia is different than ours here in the U.S.
You use a 3 phase 4 wire power system to feed a housing development as you mentioned in your thread.
Here is part of a white paper written several years ago.
Split Single Phase electrical service is most commonly found in residences and smaller commercial buildings, and is commonly used to feed AV equipment. One key advantage that single phase has over three phase is that while harmonic currents are still present, it is not possible for the �triplen� components to add in the neutral. In addition, use of split single phase can result in at least a 6dB reduction in noise floor as compared to three phase if the capacitances of the connected equipment are relatively well balanced. However, any leakage currents on the safety ground wires of split single phase load circuits fed by different phase legs will add together due to the 240V potential difference."
http://www.exactpower.com/elite/assets/pdfs/theTRUTH.pdf
(Web Link no longer works. Exact Power was sold twice since it’s inception. From what I have read Bill Whitlock was one of the Founder’s of Exact Power.)
Who is Bill Whitlock? See page 2.
An Overview of Audio System Grounding & Interfacing
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Earth grounding of the electrical service.
I believe the method used in Australia is different than is used in the U.S. Here in the U.S. every dwelling unit, House, the electrical service is directly connected to Mother Earth. Therein the electrical service entrance neutral conductor is connected to Mother Earth and bonded to the metal enclosure of the electrical service equipment, Electrical panel. At the service equipment panel the Grounded service entrance neutral conductor and Safety equipment ground are at the same potential (At the main electrical service equipment panel). Basically one in the same. They are both at ground potential.
My understanding in Australia the grounding method is different. Maybe you can say fore sure how it is done.
My understanding... The neutral conductor on the secondary winding of the 3 phase 4 wire WYE Utility Company’s Power Transformer is Connected to Mother Earth, (Ground Rod I imagine) making the neutral conductor "The Grounded Conductor" and at no place there after connected to Mother Earth. Meaning not at the electrical service again at the house, Unlike here in the U.S.
From my understanding the electrical panel installed in a house in Australia uses a, (different name for a GFCI), like here in the U.S. main breaker.) Works like a GFCI breaker but with a higher ground fault mA trip setting.
Your Safety Equipment grounding method, from my understanding, wiring method is different than here in the U.S.
Service entrance Grounded neutral conductor and Equipment Ground at the service electrical panel are not connected, Bonded, together.
My understanding the electrical panel is not made of metallic metal. Its PVC, plastic. Maybe older ones were made from metal. The point is the neutral bar and equipment ground bar are not Bonded together. If the panel is metal the neutral bar is isolated, insulated, from the metal enclosure, The ground bar is Bonded to the metal enclosure.
The safety Equipment Ground Bar is connected to Mother Earth at the house by a Ground rod. The only reference to the, ground rod at the secondary of the Utility transformer that connects the secondary neutral conductor to earth, is the soil of Mother Earth. It is not used as a low impedance ground path for a ground fault path for an appliance, equipment, or what ever Hot to equipment ground fault event may happen.
Tried to explain in laymen terms the best I could, as I understand how the ground system in wired in Australia.
So it’s not just the mains voltage that is different. To me the bigger difference is the grounding methods used.
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