What an EV charger install involves at an older house

A new electric car comes with a lead that plugs into a normal power point. It works, but it adds only 10 to 15 kilometres of range an hour. A wall charger on its own circuit is three to four times quicker. In a house built before the 1990s, whether you can have one comes down to three things.

How much power the house has

Most older homes around Preston have a single-phase supply rated at about 63 amps, sometimes less. A 7 kW charger draws 32 amps on its own. Add an oven, an air conditioner and a hot water unit on a winter evening and you are at the limit. We add up your existing loads first. If it is tight, a charger with load management watches the whole house and slows the car down when the oven comes on. That is usually far cheaper than paying for a supply upgrade to three phase.

What single phase gives you

On single phase the ceiling is about 7 kW, which adds roughly 40 kilometres of range an hour. Overnight, that covers most daily driving several times over. Three phase allows up to 22 kW, though many cars accept only 11 kW on AC. Check your car's limit before paying for more than it can take.

The cable run and the switchboard

The charger needs its own circuit from the switchboard, with its own breaker and the type of safety switch the charger maker specifies. Three things move the price:

• Distance. A board on the same wall as the driveway is a short run. A board at the back with the car out the front can mean 25 metres of heavy cable
• The board itself. If it still has ceramic fuses or no spare space, it has to be upgraded first
• The route. Conduit along a brick wall is quick. A trench under a concrete path is not

What it costs

With a modern board and a run under 10 metres, installation starts at $1,200 plus the charger, which is another $900 to $1,800. Add a switchboard upgrade and a long run and $3,500 to $4,500 all up is realistic. This is licensed work with a Certificate of Electrical Safety at the end, and none of it is a weekend job. Send Fenwright a photo of your switchboard and where the car parks, and we will tell you which of those prices you are closer to.

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