Free Electrical Tool
Air Conditioner Power Checker
Adding a split system or ducted air conditioning? Check whether your home's power supply can carry it — before the installer discovers it can't.
Ducted air con is a classic supply-upgrade trigger
Installers quote the unit; nobody quotes the power. Then installation day arrives and the home's 63A service can't carry the compressor on top of the oven, hot water and pool pump. The fix — a consumer mains upgrade or a switchboard upgrade — is straightforward when planned, and a budget blowout when discovered late.
Stack it up with everything else you're planning — induction, EV charging, pool heating — in the maximum demand calculator.
Frequently asked questions
Do I need to upgrade my power for ducted air conditioning?
Frequently, yes. Ducted systems draw 5–8 kW of input power, and on an older 63A single-phase supply with electric cooking or a pool, that exceeds the available capacity. Ducted air con is a common reason Sydney homes upgrade their consumer mains from 63A to 80A/100A or convert to three-phase.
Does a ducted air conditioner need three-phase power?
Large ducted systems (typically above ~14 kW cooling) are commonly three-phase. Smaller ducted and all split systems run on single-phase. If a three-phase unit is specified, the supply conversion is Level 2 ASP work — new consumer mains, metering and network application.
What circuit does a split system air conditioner need?
Small splits (up to ~3.5 kW cooling) can often share a general power circuit, but larger splits need a dedicated 16–20A circuit with RCBO protection. Multi-head and ducted systems always need their own circuit sized to the unit's rated input.
Why do my lights dim when the air conditioner starts?
Compressor start-up draws a large inrush current. Noticeable dimming usually points to undersized or ageing consumer mains, a long voltage-drop-prone run, or a loose neutral — the last one being dangerous. If dimming is new or worsening, have the service inspected promptly.