The Difference Between Single Phase and Three Phase
A plain-language explanation of single-phase versus three-phase supply — what each is, what triggers an upgrade and what changes at the board.
The basic difference
Single-phase supply uses one active and a neutral; three-phase supply uses three actives and a neutral, delivering power across three phases. Most homes run on single phase. Three phase spreads heavy loads evenly and delivers more power without oversizing a single phase.
What triggers three phase
The move to three phase is driven by high-demand equipment. Once maximum demand approaches the limit of a single-phase service, three phase is the practical answer.
- —Ducted air conditioning.
- —EV chargers.
- —Pool heat pumps.
- —Workshops and larger commercial loads.
What changes at the board
A three-phase installation needs a three-phase main switch, multi-phase service protection (MPD instead of SPD) and metering pre-wire for a polyphase meter, usually in a larger enclosure. EVO supplies single and three-phase boards and metering to the trade — request a quote with your supply details.
Frequently Asked Questions
How can I tell if a property is single or three phase?
Check the main switch and metering — a single-phase service has one active, a three-phase service has three. A Level 2 electrician can confirm the supply and advise on an upgrade if needed.
Do I need three phase for an EV charger?
Not always, but high-power EV chargers combined with other heavy loads can push demand toward the limit of a single-phase service, which is a common trigger for a three-phase upgrade.
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Keep Reading
Three Phase vs Single Phase Switchboards
When a home or small commercial site should move to three phase supply, and what that means for the main switchboard and metering.
EV Charger Installation: Switchboard Requirements
What a home EV charger means for the switchboard — dedicated circuit, RCD type, load management and when three phase makes sense.
Granny Flat Metering: Getting Dual Occupancy Right
Separate metering for secondary dwellings — the metering layout, box sizing and board configuration dual-occupancy sites need.