I have two phase power connected to my house, I believe it was done years ago to then allow different charges for electricity for hot water heating. Could this setup be used to increase power available for EV charging?
Many thanks, Bob.
Hi Bob – before I answer your question, I should perhaps point out to the general reader that there are two types of 2-phase electrical supplies in Australia. One is common in older suburban areas where homes were once connected two of the three phases of the 240/415V grid.
This was done for a variety of reasons, one of which was (as you’ve mentioned) to run off-peak hot water systems on the second phase. The other 2-phase system is in remote rural areas where 2-phase is 240V single phase and 480V two phase. (No 3-phase supply option available). Sounds like your situation is the suburban arrangement, so I’ll focus on that from here.Â
The short answer is having two phases won’t double the charging of an EV. EVs can charge on one or three phases, but not two. For instance, a 3-phase charger losing one phase would simply shut down as a supply fault. (A few might default to single phase charging).
In a suburban area, you could perhaps opt to connect 3-phase as a replacement (I am guessing that the water heater or stove that used it have long-ago been disconnected and, as your supply is still 2-phase, the supply line and switchboard are well overdue for upgrading). In reality though, there is little need for 3-phase home charging. However, if installing 3-phase for other reasons, a 3-phase charger is a nice bonus.Â
On the other hand, having two phases would give you an advantage if charging two EVs at the same time, as you could connect each charger to a separate phase. That would mean you wouldn’t be doubling the load on one phase by charging two cars at the same time. (At full-rate, two single phase EV chargers would take up ALL the available supply capacity of most single phase homes!).
However, I am not sure that your electricity supplier would let you keep the 2-phase 240/415V system in any update of the supply as they have been progressively phased out over the years.
Hope that helps?
Cheers
Bryce
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