What’s the difference between single and three phase power?

  • Wednesday, 2nd May, 2018

Single or three phase power refers to the amount of power supplied to your property through the use of underground or overhead power from the street. Generally, most houses have single phase power, as three phase power is typically only used in commercial and industrial situations or in larger homes that have multiple high-consumption electrical appliances. If your property is drawing a lot of power, three phase power would be installed to avoid power fluctuations.

How do I know what phase power I have?

Determining your phase power can be done in three simple steps:

  1. Locate your home’s switch board. This is usually located externally close to the front of the house, or internally in a linen cupboard.
  2. Within the switchboard you will find multiple circuit breakers. The breaker named ‘Main Switch’ identifies what phase power is available.
  3. If there is a single circuit breaker (as pictured below) you have single phase power. If there are three circuit breakers joined together by one switch (as pictured below), you have three phase power.

Single phase circuit breaker


Three phase circuit breaker

How does single and three phase power work?

The power supply comes to your home through wires from the power lines on the street. Single phase has two wires: active and neutral. Three phase has four wires: three active and one neutral. The active wires are referred to as the phases, and the neutral wires are earthed at the switchboard.

Why would my home need three phase power?

As previously mentioned, three phase power is only needed in homes with multiple high-powered appliances, and industrial properties. You’ll need three phase if you have the following:

  • Large ducted air conditioning, generally above 15 kilowatt cooling capacity.
  • Welders or other garage workshop equipment.
  • Large home with many people using electronics at peak times.
  • Homes with pools that have large filter pump.
  • Homes with multiple fridges and freezers.
  • Large ceramics kiln, or motors more than 2 kilowatt.

If you are trying to run these machines or devices off single phase power the circuit breaker will continually switch itself off as there is not enough power supply to meet the demand. For any further enquiries, do not hesitate to call our office on (07) 3395 7633.