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.
The loads pushing three phase
Ducted air conditioning, EV chargers, pool heat pumps and workshops are the usual triggers. Once maximum demand approaches the limit of a single phase service, a three phase upgrade spreads load across phases and future-proofs the installation.
What changes at the board
A three phase board needs per-phase service protection (MPD fuses), a three phase main switch, and metering pre-wire for a polyphase meter. A pre-wired kit — fuses, main switch, RCBO, sub-board and metering pre-wire in one assembly — turns a day of board building into a mount-and-terminate job.
Don't forget the granny flat case
Dual-occupancy sites often combine three phase metering for the main dwelling with a separately metered single phase supply for the secondary dwelling. Boards can be pre-built for exactly this arrangement rather than improvised on site.
Related Products
Three Phase Main Switchboards
Pre-wired 3 phase boards ready to install
Custom Main Switchboards
Fabricated in Sydney to your exact specification
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Dual-occupancy boards with two metered supplies
Switchboards for Apartment Buildings
Multi-tenancy boards for residential unit blocks
Switchboards
Main switchboards & distribution boards
Meter Surrounds
Panels & surrounds for meter installations
Meter Boxes
Galvanised steel meter boxes
Residential Construction
New builds, duplexes, granny flats and renovations
Commercial Construction
Fit-outs, mixed-use buildings and commercial precincts
Keep Reading
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.
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.
Granny Flat Metering: Getting Dual Occupancy Right
Separate metering for secondary dwellings — the metering layout, box sizing and board configuration dual-occupancy sites need.