Switch it off, but leave the wiring alone
You can turn an air conditioner off with the remote, at the isolating switch beside the outdoor unit, or at the switchboard. Don't take covers off any of them. Mitsubishi Electric warns that a non-dedicated power supply may cause overheating or fire, and connecting a unit is licensed electrical work.
What the electrical work includes
Its own circuit. Mitsubishi Electric's instructions call for a dedicated power supply, correct earthing and, depending on the location, an earth leakage breaker. The Good Guys' standard install includes a dedicated circuit with an isolator, and an RCD (a safety switch) where required.
An isolating switch. The Wiring Rules clause quoted by Access Canberra (AS/NZS 3000:2018, clause 4.19) requires a lockable isolating switch next to, but not on, any air conditioner with a compressor.
Cable between the units. Retail standard installs limit the length, with The Good Guys allowing up to 15 m of electrical cable, so a long run is extra work.
Room on the switchboard. Appliances Online's standard install assumes an up-to-date switchboard with a spare space for a new breaker, and quotes a switchboard upgrade separately.
When does an air conditioner need three phase power?
Three phase is a larger electricity supply than the single phase supply many homes have. A single split for a bedroom rarely raises the question. A big system can.
The ACT Government's guide to reverse cycle systems says ducted or multi-head units in a large house may need an upgrade to three phase, because they draw a lot of power, and that your installer can confirm it. If it looks likely, raise it before the system is ordered.
Who can do the electrical work in your state?
Victoria: electrical work on an install must be done by a Registered Electrical Contractor. A technician with a Restricted Electrical Worker's licence can disconnect and reconnect a like-for-like replacement in the same spot, and must issue a Certificate of Electrical Safety for it, but can't install new wiring.
Queensland: the QBCC says a restricted electrical licence for refrigeration and air conditioning doesn't cover installation work such as running interconnecting cables, and a refrigerant licence alone allows no electrical work.
Western Australia: adding a protective device in the switchboard and connecting fixed wiring for a new unit needs an electrical contractor's licence.
ACT: low voltage wiring needs an unrestricted electrical licence. A restricted licence holder can only disconnect and reconnect.
NSW: the air conditioning licence covers the associated wiring, but some licences carry a condition excluding electrical work, so ask to see it. Our licence guide shows how to look each one up.
Yours, and the electrician's
You can
- Photograph the switchboard with its door open and every panel left in place, and send it to the installer.
- If the breaker for an existing unit trips often, stop using it. Mitsubishi Electric says to have it checked.
Leave to a licensed installer
- Running the new circuit and fitting the breaker and safety switch.
- Fitting the lockable isolating switch at the outdoor unit.
- Any switchboard upgrade or three phase work.
- The electrical safety certificate your state requires.
What we'd do
What we'd do
We'd send the installer a switchboard photo before they visit, then ask in writing who's doing the electrical work and under which licence. A quote that says 'electrical by others' leaves you to find an electrician yourself, so we'd want the circuit, the isolator and any upgrade spelled out. For a big ducted or multi-head job, we'd want the three phase question answered before anything is ordered.
