The June 2021 storm and the 2024 storm season both produced multi-day outages across Melbourne's eastern suburbs — Mitcham, Donvale, Park Orchards, Templestowe and the bushland-edge suburbs were hit hardest. A backup generator with an automatic transfer switch (ATS) means your essential circuits — fridge, freezer, lighting, internet, sump pump, gate motor — keep running through whatever the grid is doing.
Millar Electrics installs backup generators sized to your actual essential load, with the ATS, sub-board and fuel supply work all done as one project. We also do retrofits — adding the generator and ATS to an existing switchboard rather than requiring a full board upgrade.
Sizing the generator
The right generator size depends on what you want to keep running through an outage. A 6kW unit covers the basic essentials: fridge, freezer, internet, lighting, sump pump, and a couple of general power points — enough for a 2-3 day outage with no real lifestyle change beyond not running the dryer. 10-15kW covers the basics plus partial air-con and electric cooking. 20kW+ covers most of the home. We measure your essential circuits' actual load draw before quoting so you don't end up with an over- or under-sized unit.
How the install works
The install centres on the automatic transfer switch (ATS) and an essential-circuits sub-board. We split your existing switchboard so the circuits you want backed up run through a separate sub-board, fed through the ATS. Under normal conditions everything runs from the grid as before. When the grid drops, the ATS detects the fault, signals the generator to start, and switches the sub-board over to generator supply once the generator is stable — typically within 10-30 seconds depending on the unit. Grid restoration reverses the process automatically.
Fuel options
Natural gas is the most convenient where your property already has the supply — no refuelling, runs as long as the gas does. LPG is the alternative for properties without natural gas, with run-time limited by tank size. Diesel is the most powerful and longest-running but requires onsite fuel storage and tank maintenance. We help you choose based on your property's existing services and how long an outage you want to be able to ride out.
Retrofit installations
Most generator installs in established Melbourne homes are retrofits rather than new-build. The work involves identifying the circuits to back up, splitting them onto a new essential-circuits sub-board, installing the ATS and generator pad, and running the fuel and exhaust connections. It's typically a 1-2 day job and doesn't require a full switchboard replacement unless your existing board is at end-of-life anyway.
Standards we work to
The fixed wiring side — sub-board, supply to the ATS, essential-circuits distribution — is installed to AS/NZS 3000 (the Wiring Rules), with cable sizing per AS/NZS 3008 for the generator's rated output. The generating set itself is installed to AS/NZS 3010 (generating sets), which covers earthing, neutral handling on the alternative supply, and the requirement that the ATS prevents back-feeding the grid (an absolute prohibition under AS/NZS 3010 — back-feeding a downed line can kill a lineworker). The Certificate of Electrical Safety lodged with Energy Safe Victoria documents compliance against both.