The short answer
Single-phase is one 240-volt supply; three-phase is three, which lets a home draw more power and run big three-phase equipment. Western Power's standard home connection is 63 amps single-phase or 32 amps per phase on three-phase. Converting costs Western Power's fee of $586 to $853 (where three-phase is available, 5 to 7 weeks) plus the electrician's switchboard and cabling work: AVL Electrical in Perth lists three-phase boards from $2,400 including GST (checked 12 October 2026). Most homes don't need it.
What's the difference?
A single-phase supply brings one active conductor and a neutral to the house at 240 volts. A three-phase supply brings three actives, with 415 volts between them, as Western Power describes its standard connections. Each of the three can feed its own share of the house's circuits, and some large equipment, such as bigger ducted air-conditioners, fast EV chargers and some workshop machines, runs across all three at once.
The practical difference is capacity. Western Power's Standard Connection Service for a home is 63 amps on single-phase, or 32 amps on each phase of a three-phase supply. Three phases at 32 amps add up to more total capacity than one at 63, as long as the load is spread across them.
Single-phase and three-phase at a glance
| Single-phase | Three-phase | |
|---|---|---|
| Voltage | 240 volts | 240 volts per phase, 415 volts between phases |
| Western Power standard connection | 63 amps | 32 amps per phase |
| Home EV charger | Up to 7 kW, permitted on either supply | 11 – 22 kW chargers need it |
From Western Power's EV charging connection page and published fees, checked 12 October 2026. Whether a particular appliance needs three-phase is in its installation manual; ask the supplier before you buy.
How to tell which you have
- Look at the main switch on your switchboard. A three-phase main switch is usually three switches joined together, or one wide switch
- Check the quote or paperwork from any recent solar, air-con or switchboard job, which often notes the supply
Look only. Don't open the switchboard cover or touch anything inside the meter box. If you're not sure, a licensed electrician can tell you in a minute on site.
When three-phase is worth it
A fast EV charger
Western Power permits a 7 kW charger on a single-phase supply, which charges most cars overnight. An 11 or 22 kW charger needs three-phase, and only helps if your car can charge that fast on AC. See the EV charger installation cost guide.
Large ducted air-con
Some larger ducted systems are made in three-phase versions. Check the model's installation requirements before you choose, because the supply may decide which unit you can fit.
Bigger solar and battery systems
Western Power sets the limits on solar and battery inverters connected to its network, and they depend on the supply. If you're planning a large system, ask the installer what your supply allows before you commit.
A home that keeps hitting its limit
If the electrician finds the total load of an all-electric home is too much for 63 amps, the options are a bigger connection or managing the load, for instance with a smart charger that backs off when the house is busy.
What a three-phase upgrade costs
A conversion has two parts. Western Power changes the connection at the street and the meter, and charges its own fee. A licensed electrician does the work on your side: usually new consumer mains, a three-phase main switch and a switchboard that splits the circuits across the phases.
Published three-phase conversion and switchboard prices
| Work | Published price | Who publishes it |
|---|---|---|
| Single- to three-phase conversion, overhead supply | $822 business hours, $853 after hours | Western Power, where three-phase is available |
| Single- to three-phase conversion, underground supply | $586 business hours, $647 after hours | Western Power, where three-phase is available |
| Larger home, three-phase or small commercial switchboard | From $2,400 incl. GST | AVL Electrical, Perth |
| Three-phase switchboard upgrade (low / typical / high) | $2,625 / $3,775 / $5,800 incl. GST | What's The Damage?, Perth |
Prices as published, checked 12 October 2026. Western Power's page doesn't say whether its fees include GST; business hours are 7:30am to 4pm weekdays. The Western Power fee and the electrician's switchboard and cabling work are separate charges, so a conversion costs both. What's The Damage's Perth figures were updated October 2026.
Western Power says to check first whether three-phase is available at your property, using its enquiry form. Its fee only applies where it is. A registered electrical contractor submits the application, with a preliminary notice number, and Western Power says to allow 5 to 7 weeks after the application is accepted. The switchboard upgrade cost guide covers Western Power's other fees.
Questions to ask before you upgrade
- Is three-phase available at my property, and has that been checked with Western Power?
- Could a smart charger or load management avoid the upgrade?
- Is Western Power's fee included in the quote, and is it the overhead or underground price?
- Does the quote include new consumer mains and the switchboard work?
- How long will the power be off on the day?
WA Consumer Protection suggests getting written quotes and checking what's included. The electrical contractor must give you an Electrical Safety Certificate within 28 days of finishing.
Common questions
How much does it cost to upgrade to three-phase power in WA?
Western Power publishes $586 to $853 for a phase conversion where three-phase is available (checked 12 October 2026; GST not stated). The electrician's work is separate: AVL Electrical in Perth lists three-phase switchboards from $2,400 including GST, and What's The Damage puts a typical Perth three-phase switchboard upgrade at $3,775.
Do I need three-phase power for an EV charger?
Only for a charger above 7 kW. Western Power permits a 7 kW charger on a single-phase supply, and many cars can't charge much faster than that at home anyway.
How long does a three-phase upgrade take?
Western Power says 5 to 7 weeks to disconnect and reconnect, counted from when three-phase availability is confirmed and the application is accepted.
Is three-phase power more expensive to run?
Your bill depends on the plan and how much electricity you use. Check your retailer's current price list for your plan before you upgrade, and ask how a three-phase meter would affect it.
Can I get three-phase power at any house?
No. Western Power's phase conversion is only offered where three-phase is available at the property, and it asks you to check that first through its enquiry form.
Where this information comes from
The prices, rules and advice on this page come from these published pages, checked on 12 October 2026.
- Western Power: installing electric vehicle charging stations · Network operator's connection limits for home chargers, referring to WASIR April 2023
- Western Power: phase conversion · Network operator fees and lead times
- Western Power: increase residential supply · Network operator application and design fees
- AVL Electrical · Perth electrician, published switchboard price guide
- What's The Damage?: electrician cost in Perth · Cost guide site, Perth metro prices incl. GST, updated October 2026
- Consumer Protection WA: estimates, quotes and deposits · WA Government consumer guidance, updated 4 September 2026
- Building and Energy: having electrical work done · WA Government guide to licences and Electrical Safety Certificates
