Thread: Q for sparkies - new supply

I haven't done the sums , but don;t work on 480v for your calcs. as you will be using 240v x 2 for most things , so work on 240v .

According to my tables , 330M , 40a , 240v , you need 70mm CU.
According to my pencil you need 95mm CU .
Make sure you get it right , and do not scrimp on cable size , volt drop is your enemy and you will live with your decision for ever more .
You will need 3 wires , all the same size , and the appropriate size conduit .

yeah dero its a bit of money to get wrong and pretty exxy to fix. the cable sizing will be done by the sparky when i get back there (and line up a sparky).

alternate power supply........

We recently did an energy audit on the house and use lpg for hot water and cooking. wondering what you are going to use that many amps on. our only large user is a pool chlorinator and pump which in Tas probably doesn't apply. current usage ( ha ha) is 13kwh/day. So unless you are running a dairy, 40 amps/phase is probably overkill for a house. We also have to run a biocycle system which trickles power all the time.

We are on a 3 phase supply but very unreliable and we have a standby generator which we have used for 3 days continuously as the longest time.Trees down in storms are the major issue. Recently looking at going completely off grid with the mains only supplying the welder when rarely needed.

Brother inlaw scored some ex telstra batteries which were rated at 2000 amps/cell. ran his place on solar for years and just checked the water fortnightly as you would do on any other bit of farm equipment.

Also investigate aerial bundled cable which is used in heavily tree'd areas around here. think it is at least double insulated


I would not discount the value of a property these days because it is off grid. Even if you had to include the backup generator in the sale if you ever sell it.

But DD you plan on leaving the grid on and having the house off grid! Pibby has neither, so going on grid makes more sense, who wants to buy a property where if they want to use something with a high load, they can't. Its just not cost affective.

Vern,

the only reason to keep the mains supply is for really high current devices eg the big compressor and a large old stick welder. they only get used when the kids are around anyway. If I was in his situation would look at a generator for the rare requirement for high current and as a backup for a bad weather spell.

The rest we can run off wind/solar/batteries/ inverter. Did the same in PNG due to regular power failures.

Exactly, he will need a big generator, so to do the job properly, he will be spending $30-$40k, then to sell it two years later. He can go on grid for 1/4 of that price

And to install a lower capacity supply also reduces his resale possibilities.