How can I tell if I have Single, Two or Three Phase power?

Sometimes you simply can't tell what is behind your meter panel until an electrician opens it up for a look but there are some very good clues I'll spell out here.

First, look at your meter box.

There can be as many as four devices about the size of a large margarine tub. Some may be time clocks that switch your off-peak hot water or floor heating and they will generally be deleted when you have a new solar-compatible meter installed, as detailed in this link :

https://support.solarquotes.com.au/hc/en-us/articles/5965519087247

Ignoring the time switch, if you have a close look at the retail meter, they will be marked. Some are perfectly simple like this mechanical example with a data plate that says on the left,

Phase: 1 (note on the right it also says Wire : 2)

Digital meters are often more cryptic and this is where a smart phone with a zoom on the camera can be invaluable. Amongst the model numbers and jargon there will usually be a descriptor that reads something like these common ones...

1p2w (ie 1 phase, 2 wire, the same as the mechanical meter above)

3p4w (ie 3 phase, 4 wire)

Or the clue here for this 3 phase smart meter is the display showing Line1, Line 2, Line3

plus the mention of 3 by 240/415 volts.

You may have one, both, or even three or four of these meters in different arrangements.

There could also be a device about the size of stick of butter, made of black bakelite, with tamper proof seals. Sometimes marked marked as SPD or MPD, this is the main supply fuse and if they're present you'll have one for each phase. For further proof, there can be a Main Switch or Meter Isolator.

In unmarked vintage bakelite, a 3 phase main switch might look like this black one :

However any board that's less than 30 years old will have what we call DIN rail mounted switchgear, Circuit breakers, safety switches, surge protectors, all clip on a chassis where each 17mm wide unit is referred to as a pole.

Single phase circuits will have a single pole switch or breaker, with a single toggle to operate them.

Two phase circuits will be two poles, 34mm wide

Three phase circuits will be three poles, 51mm wide

AND the toggles will be joined together so they operate as one device.

The images are real world examples :

This din rail has a solar consumption meter on the left in blue,

9 single pole circuits

and a 3 pole breaker on the right hand end, which confirms this is a 3 phase installation.

I mention this jargon about poles because any new solar inverter will need space in your switchboard for at least one pole, or even six or eight poles in a separate enclosure, depending on the model. Making room for this extra equipment can sometimes mean extra expense to upgrade the switchboard.

This "breakout box" has about 20 poles worth of gear to enable a Fronius Gen24 battery hybrid inverter. Once the cover plate is installed to finish this unit, the red toggle will be labelled main switch.