Engineer's Notes: rules differ, physics does not
Same equipment, different words
An 11 kV ring main unit is "HV" in Auckland, "MV" in Dubai and "medium voltage" in Houston. The physics is identical, but contracts, safety rules and authorisations follow the local words, so get them right on drawings and specifications.
The utility sets the frame
Every utility publishes connection rules, standard drawings and approved equipment lists. They decide voltages, substation layouts, earthing, metering and the approval path, often on top of national codes.
Standards travel, editions do not
IEC standards are adopted nationally as AS, MS IEC, SS or BS EN with their own editions and amendments. Always use the edition the authority calls up, not just the latest IEC text.
Registration matters
Signing HV designs usually needs local registration: CPEng in New Zealand, CPEng or RPEQ in Australia, PE in Singapore and Malaysia, and authority approval as a consultant in the GCC.
Frequently asked questions
What counts as high voltage?
Under AS/NZS 3000 and the New Zealand regulations, high voltage is anything above 1000 V AC or 1500 V DC. IEC 61936-1 covers installations above 1 kV AC. Many GCC and Asian utilities call 11 to 33 kV medium voltage and reserve high voltage for 132 kV and above, while ANSI usage puts medium voltage at about 1 to 100 kV.
What distribution voltages are used in the GCC, Australia, New Zealand and Asia?
The UAE mainly uses 11 and 33 kV, Saudi Arabia 13.8 and 33 kV at 60 Hz, Australia 11, 22 and 33 kV, New Zealand 11 and 22 kV with 33 kV sub-transmission, Singapore 22 and 6.6 kV, and Malaysia 11, 22 and 33 kV. Low voltage is 230/400 V in all of them.
What is the MEN earthing system?
Multiple earthed neutral, used in Australia and New Zealand. The network neutral is earthed at many points and the installation neutral and earth are joined at the main switchboard, which makes it a TN-C-S system.
What phase colours are used in different regions?
Australia and New Zealand use red, white and blue phases with a black neutral. IEC 60445 and Singapore use brown, black and grey with a blue neutral. Older GCC installations commonly use red, yellow and blue. Always follow the current regulations of the utility.
Which approvals does an HV project need?
Typically a connection or load application to the utility, utility approval of the substation design and equipment, fire authority approval, and utility inspection and energisation. Generation, customer-owned HV equipment and critical facilities add further steps.
Topics: standard voltages · HV definition · MV · voltage ladder · DEWA · TAQA · SEWA · EtihadWE · SEC · SERA · DNSP · AEMO · EDB · Transpower · SP Group · EMA · TNB · Energy Commission · MEN · TN-S · phase colours · standards map · approvals · professional registration
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