3-phase power - What is it, and why do you need it?

Posted on Oct. 1, 2022, 3:24 p.m.

3-phase power - What is it, and why do you need it?

What do all these 'phases' mean?

In NZ, the typical household and small business have a single meter, which may or may not be AMI communicating (ie a smart meter), and that's it. The meter is usually connected directly to the property to measure and monitor energy use across the property.

Most households are set up with your standard '1-phase' power and meter, which means there are essentially two wires - one active, and one neutral. This supplies power at around 230V +/- 6% (with frequency of 50Hz), and is sufficient to run small equipment and appliances in most homes and businesses.

An alternative set up is '3-phase' power, which has four wires - three active, and one neutral wire. It supplies power at 400V +/- 6%. When we bring in a 3-phase power supply, it essentially triples the amount of power available at any one time. This is because we have access to all '3-phases' (or, channels/lanes, if you like). This means we have 3x the number of 1-phase supplies connected, effectively.

What is it used for?

For larger sites, especially warehouses, 3-phase power is required as it provides sufficient load to meet the power requirements of the larger appliances and equipment typically used (e.g., forklifts, fork hoists).

Usually, you'd find these types of power configurations common in industrial and medium/large commercial environments that use induction motors, other electric motors, and other heavy loads. For example, in large industrial factories with machinery that use heavy loads, or medium-sized storage warehouses that use electric fork hoists that need to be re-charged regularly.

What set up is required?

3-phase power typically requires a higher installation cost, and higher running costs, depending on your system, your electricity retailer, and the operator of the distribution network your premises is located in.

For example, 3-phase often involves more complex metering due to the need to monitor different channels, which typically a meter that is more highly capable is needed, and therefore higher metering lease fees. Your network operator may also charge you a higher fixed and variable cost due to the greater impact your premises and its load has on their network.

Upgrades to the premises' internal infrastructure might also be required, such as equipment upgrades to your switchboard to support 3-phase power. This is because most standard households or business sites won't be capable of managing the heavier loads, and will need to be converted to support 3-phase power, unless a previous tenant already had it installed or requested it be installed with their landlord/property manager.

What are the costs?

If you're thinking that this all sounds pricey, you're right. Typical set up costs range from anywhere between a couple of thousand dollars, to over $20,000. It all depends on how complex the installation and upgrade might be, for example, whether upgrades are required to connect your property to the distribution network. It's best to talk to a qualified electrician about this to get a few quotes to compare before deciding.

However, a better approach, if you're looking to move, is to just make sure the premises you're moving into has 3-phase power available. If you're leasing the premises, you can discuss this with your property manager or landlord directly. If 3-phase isn't available, you can maybe work through with your landlord or property manager on other alternative options, or potentially investigating upgrade costs to the site to provide a 3-phase power supply.

Do you really need it?

Costs to install 3-phase power is largely site-dependent, but upgrading won't be easy. If you're considering 3-phase power for your property, make sure you/your business has a clear need for it, and that it is well justified. Explore if there are any other options for your equipment or machinery that you can use that may not require a 3-phase power supply. For example, instead of using electric fork hoists, you could consider gas-powered fork hoists in the interim while you look for a longer-term solution.

At Tensor, we provide our commercial and business customers with flexible pricing plan options that's specifically catered to what they need. If you're currently considering 3-phase power, or already reside on a premises with 3-phase power, and are looking to supply power to your property, contact us now using our website chat, our contact email info@tensor.co.nz, or send us an email using our contact form here, to talk through your available options.