Three phase power upgrade in Melbourne: do you need it, and what does it cost?

Single phase, three phase, and what changes

Most Melbourne homes are fed by a single phase supply, which was ample for a house running a fridge, a television and an electric stove. Three phase brings three active conductors instead of one, which raises the total the property can draw and lets large appliances start without dragging the voltage down across the house.

The visible symptom of running out of single phase capacity is lights dimming when the air conditioning starts, or the main switch tripping when two large appliances coincide.

You may not need three phase

This is worth saying plainly, because three phase is a significantly larger job than the alternative. A lot of homes told they need it actually need a properly sized single phase mains and a bigger switchboard.

The way to know is a maximum demand calculation against the equipment you actually intend to run, not a rule of thumb. We do that before recommending anything, and we would rather tell you the cheaper answer than sell you the bigger job.

What the work involves

• Assessment of the existing mains, the point of attachment and the meter position.
• Maximum demand calculated against your intended load.
• Application to your electricity distributor, including any site inspection they require.
• Consumer mains replaced from the point of attachment to the board.
• Switchboard replaced or reconfigured for three phase distribution.
• Load balanced across the phases so one is not carrying the house alone.

The distributor is the long pole

Your electricity distributor owns everything up to the point of attachment and the metering. Any change there is theirs to approve and often theirs to carry out, and their timeframe is typically one to three weeks.

That is the part of this job nobody can compress. If you have plant, a pool or a charger arriving on a date, start the conversation early rather than when the equipment lands.

How much does a 3 phase power upgrade cost in Melbourne?

We do not publish a flat price for a 3 phase power upgrade, because four things set the price and they differ on every property. How far the consumer mains run from the point of attachment. Whether the switchboard can be reused or has to be replaced. What your distributor charges for its side of the work. Whether the meter panel or an asbestos backing board needs attention. Two houses on the same street can land a long way apart.

What we can do is give you a fixed price after a free site visit and a maximum demand calculation. It states what is included and what would change the number, and it separates our charges from the distributor’s so you can see which is which before you commit.

3 phase power installation Melbourne: the mains, the switchboard and the meter

Upgrading to 3 phase power on an existing house is not a matter of fitting a bigger version of what is there. The board has a different layout, with the load spread across three phases, and it normally goes in with the mains so the changeover is one outage. A 3 phase switchboard upgrade on a board that is already new may be possible. On an original board it is part of the same job, so 3 phase power upgrades there always include the board. Our switchboard upgrades page explains what that covers.

The meter belongs to your distributor, so a three phase meter upgrade is their work and their approval. The mains and the board are the consumer side, and that is ours. A new meter on its own, with the old cable and board behind it, leaves the house with the same bottleneck.

Overhead to underground conversion, and underground service connection for a new build

Whether it is a three phase electricity upgrade on an old house or an underground connection for a new one, the work is mains work. If your supply comes in overhead from a pole, converting to an underground service follows the same distributor process as a phase upgrade. A new build needs its underground service connection planned before the driveway is poured and the site is landscaped, because the conduit has to get from the street to the board.

Tell us the plans and the equipment list early and we size the service and the three phase installation together, rather than finding out after lock-up that the supply will not carry the ducted system and the charger. For those loads, see air conditioner installation and EV charger installation.