Powercor's own charges for a supply alteration run about $600 to $4,500 where three phase is at the pole. If the line needs work, look at a battery.
Moving a property from single phase to three phase is a supply alteration. A registered electrical contractor lodges it with Powercor, Powercor's own charges for an alteration typically run $600 to $4,500, and most jobs take three to eight weeks, provided three phase power is already on the line outside. If it is not, the job becomes a network upgrade, and on a long rural run that is where the big money is. Before committing, check whether you actually need a third phase or just more power, because a battery system can often supply the second and not the first.
When you genuinely need three phase
Three phase earns its keep when the property runs three phase machines or a large total load:
- three phase motors on pumps, grain handling, compressors, workshop machines and refrigeration plant
- a large shed or farm load where splitting it across three phases keeps current on each phase manageable
- faster three phase EV charging, if the car can take it (see EV charging)
If the only problem is that the single phase supply trips when several big single phase loads run together, you may need more power rather than another phase. Our article on more power without a grid upgrade covers using a battery inverter to top up a limited supply at peak times.
What the upgrade involves
Powercor's page on changing an existing supply lists changing between single and three phase as a common alteration. The process:
- only a qualified registered electrical contractor can submit the alteration application, through Powercor's eConnect portal
- all work needs a Certificate of Electrical Safety
- Powercor gives an indicative cost when the application is submitted
- typical Powercor costs are $600 to $4,500, depending on the scope of work, whether it is done outside business hours, and how many site visits are needed
- most works take 3 to 8 weeks; missed appointments, unsuccessful field visits and retailer service order delays slow it down
That covers Powercor's side. On your side the electrician typically replaces the consumer mains and the service to the meter, upgrades or replaces the main switchboard, and rewires circuits to balance the load across the phases.
When the network has to be upgraded
Powercor's page is clear that if the existing network cannot support the change, a network upgrade is needed and its separate network upgrade process applies. In the country that usually means the line past your gate is single phase, a single wire earth return line, or has no spare capacity at the transformer.
For a sense of scale, Powercor's indicative connection costs for embedded generation list a rural 22 kV overhead extension at about $0.2 million per kilometre and underground at about $0.9 million per kilometre, before any work to remove a network constraint. Those figures are for generator connections, not load, but they show why a three phase extension a few kilometres down a rural road is a different conversation from a $4,500 alteration.
When a battery or a hybrid inverter does the job instead
You need more single phase power, not a third phase. A battery inverter charger with peak assist adds battery power on top of the grid. Victron's MultiPlus-II has PowerControl to stop it overloading the grid or a generator and PowerAssist to boost the supply from the battery at peak demand.
You already have three phase and want solar and storage on it. A three phase hybrid inverter puts solar and a battery across all three phases. Fronius describes its Symo GEN24 as a three phase inverter with a battery connection, and the 10.0 model carries a nominal 10 kW AC output. Be clear about backup: its basic PV Point socket powers devices only while the sun shines and has a maximum switchover time of 15 seconds, while Full Backup for the whole site needs a battery and a switching device.
You have two phases. Some rural properties have a two phase supply, two live phases rather than three. One Macedon Ranges farm in our projects runs two separate Sigenergy systems in its shed, one per phase, each with its own battery stack. Because Sigenergy treats each phase as an independent system, one phase's battery can be full while the other is empty, so we built our own controller on Sigenergy's developer API that reads both systems and plans each night's cheap window charge per phase.
You have one or two three phase motors on a single phase supply. Ask your electrician whether a drive that takes single phase in and gives three phase out suits the motor. For small motors that can be cheaper than changing the supply.
Off grid sites and three phase
An off grid property can have three phase without any network at all. Victron says the MultiPlus-II supports parallel and three phase configurations, and larger sites use Quattro inverter chargers stacked one per phase. The trade off is cost and complexity: three units, a battery bank sized for the total, and a generator that suits three phase. Our off grid hub and why we build on Victron explain the design.
Questions
How much does it cost to go from single phase to three phase in Victoria?
Powercor quotes typical alteration costs of $600 to $4,500 for its part when the network can support the change, plus your electrician's work on the consumer mains, switchboard and wiring. If the line needs upgrading, the cost depends on Powercor's network upgrade process and can be much higher.
How long does a three phase upgrade take?
Powercor says most alteration works take 3 to 8 weeks depending on complexity, and that missed appointments, failed field visits and retailer service order delays can extend it. Your electrician arranges the appointments, so apply early.
Can I put a three phase battery on a single phase supply?
No. A grid connected inverter connects to the phases you have. On a single phase supply you use a single phase battery system, and if you need three phase machines you either upgrade the supply or look at drives for small motors.
Do I need three phase for a big solar system?
Not always. What matters is how much Powercor will let the connection export and how much of the solar the site uses itself. Ask your electrician to check what Powercor will allow on your connection before deciding.
Send us a photo of your switchboard and meter, a list of the machines you want to run, and your address, and we will come back with the options, or start at our contact page.
Sources
- Powercor, change your existing power supply
- Powercor, embedded generation connection process and indicative connection costs
- Victron Energy, MultiPlus-II inverter charger
- Fronius Australia, Symo GEN24 10.0 technical data
Written by the Trentham Energy team.
