3 phase electricity

[trenyboy]

Hi,

Will 3 phase electricity cost me anymore than single phase in terms of general eletrical appliances?

The reason I ask is I am building a new house and have organised for a 3 phase underground supply to be installed as it didn't cost much more than the single phase and I thought long term if we ever needed it it would already be there (ie. Air conditioning or something)

Apart from setup cost of the supply, will it cost me anymore to use or will it not make a difference?

Thanks
Trent

[dennford]

I believe that 3 phase is actually cheaper in the long run same hp - less electrickery. I have also surprisingly found that a grundfoss 3 ph submersible pump was cheaper to buy than the single phase version of the same pump.

Denn

[Ruddigar]

G'day Trent,

Some people will be a better source of information than I, but the short answer is;

Three phase electricity is generally a more efficient energy supply, especially in large appliances such as air conditioners or woodworking machines. The main reason that most people don't have it is because it's installation cost is often cost prohibitive.
As dennford has mentioned, you will often find that machines/appliances that run a three phase motor can be cheaper than the single phase alternative.

[trenyboy]

Thanks guys,

So its more expensive to wire and connect the house to from the power pit? The cost to have a 3-phase underground pit installed was only an additional $100 so i thought i may as well.

But if its going to be a considerable cost to connect into then i am wondering if it is worth it?!?!??

Thanks again

[rrich]

When thinking in terms of the shed...

In the US, there are a lot of used three phase machines available at prices that are significantly less than a similar single phase machine. The reason is that there is less of a market for three phase machines. If the typical OZ residential electrical power is single phase then someone with three phase power has an advantage when it comes to shed machinery.

[dennford]

When thinking in terms of the shed...

In the US, there are a lot of used three phase machines available at prices that are significantly less than a similar single phase machine. The reason is that there is less of a market for three phase machines. If the typical OZ residential electrical power is single phase then someone with three phase power has an advantage when it comes to shed machinery.

By the same token there would be less of a market if you wanted to sell - mind you the fact that most 3 phase machines are heavier and expected to outlast a single phase, why would you want to sell anyhow?

You have 3phase at the pit then the extra cost of taking it to the house board and then to a shed would not be all that great (4 core wire instead of 2 core) plus one or two outlets.

Go for it, you wont be sorry.

Denn

[Rossluck]

The main advantage of 3 phase for the average house is being able to spread the 240 v load across the three phases. So, for instance, the lights might be on one phase, and the power outlets divided between the other two. As well as allowing more 240 v capacity in your house and shed, this means that if you trip out your power by cutting a cord or something, your lights will stay on.

The second advantage is that you can buy 2nd hand 3-phase machinery fairly cheaply because the market is reduced to 3-phase owners.

When it comes to things like air conditioners, however, inverter technology means that 240 v AC's are probably more efficient.

The bottom line is: if you can afford it, get it.

[tcns]

In the past if you have applied for 3phase for an air conditioner then the energy company has done their part for free, that way it only costs you what the sparky charges to move your house across the 3 phases. That can be a $500+ saving.

Just don't mention that it is for the shed or for anything but air conditioning....

Tom

[thatirwinfella]

three phase motors generally run with more torque and less vibration compared to a single phase motor of the same output. the actual motor tends to smaller as well.

[trenyboy]

Thanks, you've all been a big help. Just one other thing, how does surge protection work for 3 phase power? I have added a surge protector into my electrical options, does this mean I would need to add 3, one for each phase?