Most residential homes have a ‘single phase’ or ‘three phase’ connection supplying 230 volts. For a modern family home, this connection is often 60 amps for a single phase, or 32 amps across three phases. Your fusing could be more or less if your house is smaller, larger, or was built at a time when fewer electrical devices were used around the home.

Small commercial buildings usually need more capacity, such as 100 or 200 amps. Large commercial stores or warehouses could need 400 amps to 1200 amps of capacity depending on their size.   

Your capacity needs will vary depending on the amount of power you are using at your property, and there is no “standard capacity” or one-size fits all.

  • How can I find out what capacity I have?
    • You could check with the previous owner of your property.
    • Contact your electrician.
    • Get in touch with MainPower (03 311 8300, or There may be a fee for this service. 
  • Why would I need to increase my capacity?

    If you are thinking about altering the heating source within your home (e.g. going from a log burner, to multiple heat pumps) or you wish to run extra appliances from your home (e.g. charging an electric vehicle, or a spa pool), you may need to increase your capacity in order to meet the added demand of such appliances. Your electrician will be able to advise you on what will be required. MainPower are happy to work with your electrician, or to provide you with information directly. Get in touch by calling MainPower on 03 311 8300.


  • What happens if I need to increase my capacity?

    MainPower charges for increasing capacity at an ICP (Installation Control Point, i.e. where the house, shed etc connects to the network). Please contact us to discuss these charges.

    To start the process, check that the wiring inside your house or business is capable of taking the increased current. You electrician will be able to help you with this.


  • Why do you charge for capacity upgrades?

    In some cases, in order to increase the load at an existing ICP (Installation Control Point, e.g. house or shed), MainPower will be required to carry out significant upgrades to the electricity distribution network (e.g. upgrading the transformers, power lines etc supplying the ICP). This can incur a significant cost. 

    In order to cover this cost, MainPower charges for all capacity increases. This fee contributes towards any network upgrade work that may be required as a result of the specific capacity increase, or other capacity increases in the future. In this way, no single customer ends up being charged for the entire cost of a network upgrade, but rather the cost is spread across all customers who will benefit.

    Network pricing is currently being reviewed across the industry and MainPower is investigating the best way to charge our customers.

    If you are interested in being a part of this discussion, please email or check out our community consultation page for ongoing opportunities to share your views.