Do I need 3-Phase Power for my new home?

0FoxGiven on 05/02/2019 - 11:37
Last edited 05/02/2019 - 18:08

Hi all,

I'm having my new home built in Victoria and I am going all-electric (no gas) in the house. I will be having a solar panel system installed soon after the house is built.

The main high amp electric power draws would be :

  • 14kw Reverse cycle ducted heating and cooling system
  • Induction cooktop
  • Heat Pump water heater
  • Future-Electric Car (Possible few years down the line)

Now my site supervisor has advised me that a single phase power supply may not be a handle this kind of current draw and I might need to have a 3-phase power supply (currently being investigated).

Looking for advise on whats the best way to go, how much it would cost (time and money) to get 3 phase power and is there an alternative approach that I can consider? Gas is not an option for me, I don't want it. Is there a separate annual fee for having 3-phase power supply to a house in Victoria?

Home & Garden

Comments

  • [Deactivated] on 05/02/2019 - 11:40

    How much did the builder say it will cost to install now, vs doing it later if the energy requirements change down the road?

    • 0FoxGiven on 05/02/2019 - 11:44

      Its currently being investigated. I don't have a number now, I was hoping someone here can could give me a ballpark number.

  • HighAndDry on 05/02/2019 - 11:44

    Does the site supervisor perhaps have any professional electrician contacts you might be able to talk to?

  • [Deactivated] on 05/02/2019 - 11:44

    If all three of those big units are running at the same time you might be marginal*

    I have similar setup but water is electric and off peak so is only running between midnight and 3am.

    I am on single phase with no issues.

    *not an electrical expert

    • 0FoxGiven on 05/02/2019 - 11:49

      Ah so you have a reverse cycle ducted heating & cooling + Induction cooktop as well?

      Yes. I'm not too worried about water heating as I can set the time I want it to happen. I'm just worried about the A/c and the induction cooktop as it is quite likely that both maybe running at the same time.

      • [Deactivated] on 05/02/2019 - 12:12
        +1

        Yes. If the cook top is raging and the ac kicks in we get, on occasion, a slight dimming of our ceiling lights.

        Ducted reverse is the best though. We have ours zoned into 5 sections to manage room temps.

        Can you set a timer on heat pump hot water units. My understanding is that they can't be on an off peak meter.

  • SBOB on 05/02/2019 - 11:52
    +2

    if you're getting solar, theres also the possibility for a higher output system with 3-phase
    single phase is limited in most places to 5kw, some places 10kw, without seeking special approval.

    3-phase isnt (well, it is, but 3x those numbers and more likely to gain special approval if it was over due to load balancing)

    also, cost to get it at time of build will be minimal compared to after

    • 0FoxGiven on 05/02/2019 - 12:10

      Thanks SBOB. Interesting point you make about output for a solar power system, I wasnt aware of that.

      Do you know if there is an annual fee associated with having a 3-phase power supply? I maybe willing to fork out money to get 3-phase but I would be reluctant if there is an annual fee associated with it as well.

      • SBOB on 05/02/2019 - 13:36

        nope, I dont see any extra fee on my elec bills regarding it

        only additional costs should be during install
        - 2 extra phase cables from supply to house
        - additional cost for three phase meter
        - any electrician variations for splitting sections of house to different phases (eg air conditioner just one one, etc)

        House i bought came with it so not sure what these would be during build time, but would definitely be much cheaper than post build with the supply line from the grid plus needing to organise disconnect/reconnect electrician etc

  • HardlyCharly on 05/02/2019 - 12:08
    +3

    Future proofing, going to need that 3 phase for electric cars in the future, might as well get a 30 amp Mennekes socket installed in the garage while you're at it.

    • 0FoxGiven on 05/02/2019 - 12:12

      Exactly! I would definitely be considering an electric car coupla years down the line once they become more affordable

  • Densor on 05/02/2019 - 13:41
    +3

    3 Phase is great for high load devices such as your 14kW air con and your future pool pump and 3 phase welders in the garage. 3 phase motors distribute the current draw the 3 phases and are more efficient to run with less losses (long term energy savings vs higher initial cost). They don't rely on a starting capacitor and are therefore more reliable. The rest of the house can be balanced across the phases. Cooktop on one phase and wall oven on another.
    The incoming wiring might be smaller in size based on maximum demand, but you will be paying for an extra 2 single core cables. The Energy authorities don't charge you any extra. There is still only one consumption/electricity meter and you get charged once and not for each phase.

    • 0FoxGiven on 05/02/2019 - 13:53

      Thanks Densor!

      Just FYI, the Heat-Pump system is just an electric water heating alternative to gas water heating for normal household use. Its not for a pool :)

      Don't I need to get approval for getting 3-phase power supply? And the costs for laying the extra cable and the electrician to get the work done? I heard the costs could come up to $3k. I just want to know if thats actually a realistic number for a house thats only going to start construction.

      • SBOB on 05/02/2019 - 14:22

        I heard the costs could come up to $3k

        that sounds more like 'post building' costs..
        a chunk of which would be electricity provider electrician having to attend for both disconnect and reconnect (probably $1k)

        for a new build I'd be wanting cost breakdown/justification for anything north of about $1k

        (also check home builder forums eg. https://forum.homeone.com.au/viewtopic.php?f=31&t=21190)

        • 0FoxGiven on 08/02/2019 - 19:08

          My builder got back to me with a quote of $4500 :-/

          I checked with few electricians and apparently the number isn't very surprising and they think it would come up to 3.5k-4k!

          • SBOB on 08/02/2019 - 19:14

            @0FoxGiven: Nfi how pulling two extra mains wires, 2 more mains fuses , an upgraded meter and a bit of extra elec hours is 4500…

            That's builder gold class variation right there.

            Post build, believable..at time of build..crazy talk.

            • 0FoxGiven on 12/02/2019 - 10:49
              +1

              @SBOB: Ok that price included a variation charge penalty for getting this change after the construction started. I got the builder to accept that this was not my fault that they didn't identify the need for a 3 phase connection early on. Now the price of getting the whole thing done is $2000. Sound reasonable?

              Apparently the cost of getting the power company truck come over to isolate the power while the electrician makes the 3 phase connection magic itself costs $700ish. And then the previously laid single phase wiring needs to be changed to 3 phase so involves re-work etc.

              • 1337yang on 21/02/2019 - 18:21
                +1

                @0FoxGiven: Hi I'm currently building as well, completing in March.
                We were advised to upgrade to 3 phase by the builder and aircon company. It was priced prior to start of the build, cost of just under 500 for " running 10mm cable from dome to Meter box"
                We also have heat pump and induction cooker.
                Good luck!

  • Euphemistic on 08/02/2019 - 20:25

    Is your meter box in the garage? If so, unless your current load requires 3 phase I don’t see any need to go further than getting 3-phase supply wiring into the meter box and only connecting it when you need to. Having the supply available in the garage future proofs you for the e-car. You’d be unlikely to need it for the rest of your house, unless your sparky says you need it now.

  • akyeeeahdude on 30/03/2019 - 18:20

    I built in late 2009 and adding 3 phase was about $750 from memory.

    I now have:

    8kw, 3.5kw and 2.5kw split a/c
    Induction cooktop
    Heat Pump water heater
    pool pump

    When I had the induction cooktop put in recently, I asked the Electrician if I would need to start thinking about 3 phase. He said no and would be surprised if I would ever get close to maxing out the single phase capacity, even with the induction cooktop being added. He said if I wanted to add it, he could do it for $1500, provided he could get the wiring through the existing conduit from the street to house.

  • Sval on 21/06/2022 - 18:45

    Hi @0FoxGiven:, did you go ahead with the 3-phase electricity installation? How much did you end up paying for the installation? Also, do you have to pay extra monthly service charges for having a 3-phase? I am planning on building a new home so thinking it it's ideal to get the 3-phase for future use?

    • 0FoxGiven on 21/06/2022 - 19:31

      Yes I did go ahead with it. I had to pay $1200ish to have the wiring done. It would have only costed $400-500 if I had informed the builder before the build started. There are no monthly costs associated with a 3 phase connection.

      As for future use, it useful if you plan on going all electric / if you plan on buying an electric car (unavoidable I guess after a decade) / if you want a grid connected PV system thats larger than 7Kwh generation.

      • Sval on 21/06/2022 - 20:23
        +1

        Thanks a lot for your quick response. Yeah, I might potentially buy an electrical car in the future. If there are no extra service charges I rather pay now and get the 3-phase installed as installing after the construction will be expensive. I will include it in my building plan. Thanks again!!

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