How does 3 phase install work?

laspaz, Mar 11, 11:18am
I am going to be relocating a building shortly to a site with no services. I want to have 3 phase power for my shed that will be built in the months following.

Am I best to run services to the house site before moving the building to the site or after? The services will be crossing the section and the truck and house will have to go over the lines.

Do I request 3 phase service to the house, and then run it off to the shed later? Is it usually a separate meter for the three phase? The building does not currently have a meter box because it was run off a generator in it's previous off grid use. I called the lines company and the said the subdivision was set up with 2 phases per section and two sections sharing a pillar box. The neighbour I share with does not have three phase, so does that mean I should be ok?

snoopy221, Mar 11, 11:24am
No doubt a sparkie will pop in ere there's a few of em floating around but i read it as they have wired as stated with 2 phases per house at the pillar boxes or gyros.

As to wether 3 phases are available via the gyros-as in wether you have to have an extra trench and cable run from a corresponding neighbourly gyro to give you ALL 3 phases. Or wether only 2 phases are available at the gyros is the first question you need to know from ya power company.

laspaz, Mar 11, 11:32am
Thanks Snoopy, this is the response I received from powerco when I asked if 3 phase service was available:

"This subdivision was reticulated for 2ph per lot if you require more please contact a Powerco Approved contractor to install another fuse and also to confirm there is room the pillarbox."

snoopy221, Mar 11, 11:49am
Hopefully that may mean all 3 phases are at the gyros. but hey until ya see the plans or open of the gyros mmmm

tsjcf, Mar 11, 3:37pm
Will be three phase at the pillar box, Need to request when you do the install.
Normally they will install a 3 phase poly meter plus a single phase meter for the hot water assuming you want electric hot water at the controlled rate.
Would normally run to the house switch board then a feed off to the shed depending on whats closer.
You dont want to pay for 2 connections.

woody89, Mar 11, 4:23pm
We have 3 phase from the house meter board to the shed & a deep well pump. Have always had expensive power. Found out recently that due to the 3 phase, we are being charged commercial rates for everything. Took visits out here from Waipa Networks & a bit of arguing with them & Trustpower to get it changed to residential. Naturally no money was reimbursed! Just something to consider- unless of course you are a commercial concern.

laspaz, Mar 11, 5:25pm
Yep good advice thanks. Will be on gas for water so hopefully just one meter then.

laspaz, Mar 11, 5:27pm
I had heard about this. The advice I received was that if it's going to your house then it's typically charged at residential rates. I don't intend to run a business any time soon.

supernova2, Mar 11, 11:06pm
My 2 cents worth.
If the buildings are going to be shifted over the service trench then I'd be getting the services put in after the building.
You definitely don't want two connections so I'd get the power connected to which ever building is closest to the street pillar and then run from that point to the other building. If the closest building isnt on site yet then can put the meterbox on a pole and then when the building goes up you just build it into the wall.
Best bet is to select your electrician and then get him to sort it all out with the lines company. As you have already discovered the lines company really wont be very helpful to the public - they want to deal with the qualified people who are supposed to know what they are doing/want. Do check that you can get 3 ph on a residential rate rather than commercial. Friends of mine had 3ph at their lifestyle block. When he died the widow had the 3ph ripped out and changed to 1ph as (she said) it was just too expensive to keep the 3ph. Hate to think how much that cost as there were 3 houses and 3 big workshops/sheds all with 3ph.

woody89, Mar 12, 7:35am
We have never run a business from here, the meters etc were set up by the original owners, yet Waipa Networks were very reluctant to change the rates.

laspaz, Mar 12, 9:26am
My only 3 phase machine is a big compressor, but had hoped to pick up some more 3 phase bits. I have asked my power company about the rates I would be paying so will be interesting to see what they say. I guess I could get a generator, or vsd or something if it comes to it.

I was planning to wait on the services trench till after the building is moved on to avoid potential damage, but thought it was worth asking. Thanks.

onl_148, Mar 13, 12:10pm
Just remember the cable to run from the street to the house / shed is expensive, do not run 3 phase to the house then to the shed if it going to add any extra distance. you require 3 phase in the shed and single phase in the house !

laspaz, Mar 13, 1:00pm
Oh ok, the road to the house is 150m and from the shed to the house meter about 8 extra. Trouble is that the shed won't exist until after the house will have power connected.

It's not an extra cable from the road is it? Same cable that is then used for single at the house?

laspaz, Mar 13, 3:53pm
My power company have said:

"Residential customers can have 3 phase power, however only up to 60 amps. Anything greater will incur commercial charges."

What does that mean in real terms? Is 60 amps workable or a waste of time?

dastedly, Mar 13, 4:28pm
60amp is what most homes have . so is have 3ph that give you in a way 3 x 60amp .in a way 180amps. Two people you deal with first is line co and then the retailer one you pay power bill to . Retailer would not know what 3ph is . Can be hard work to sort out at times. Myself get 100amp x3ph and on residential rates . Other thing think about night rate . I have 2 meters ,24 hour uncontrolled and one night rate that give power only between 11 pm and 7am . I paid around 12 cent kw and 24 hour power 23 cents. I have hot water and water pump up to tank on night rate

laspaz, Mar 13, 7:19pm
Thanks, yep shouldn't need separate meter for night rate as doing gas hot water. It sounds like 60 amp should be fine for my light usage too.

supernova2, Mar 13, 9:55pm
3 ph cable simply has 3 (live) wires one for each phase. If you want you can use all 3 separate phases in your house. There are lots of houses about that have a 2ph feed (mine does). Often electric stoves used 2 phase.

Im not an expert but I'm thinking that if you only use 1ph (off the 3ph cable) for the house you might just end up with some load sharing problems when you try and fire up your 3ph equipment in the shed.

I think the best option is to get your sparky on board before you decide where to put your meterbox. If the best place will be the shed then just put it on a pole until the shed is built. My friends had their meter box on a pole for about 3 years while building a new (additional) house.

Talking of meters my daughters house has 6. Its 2 phase and has nightstore heaters and was at one stage 2 flats. You don't want to see her monthly bill.

aredwood, Mar 13, 9:57pm
Definitely run both the house and the shed on 3 phase. Due to the very long distance involved - 150M. The cable for 3 phase could be cheaper than single phase. This is due to voltage drop - longer distance needs bigger cables. But with 3 phase, you have more voltage (400V phase - phase) meaning you can have smaller and cheaper cables for 3 phase, than with single phase.

Get the meter box on your house setup as the main switchboard. And the internal switchboard setup as a sub switchboard. This means that when you build the shed, The cable to it can be joined into the meter box, instead of having to go to the internal house switchboard. (Less cable needed, and less need to use larger cables to still comply with voltage drop rules).

If you weren't building the shed, you would then be able to get 3 Phase to the house with 32A per phase. - Massive saving on cable costs. You could still do that anyway - But not recommended, As it is always far more expensive to upgrade later compared to getting it done from new.

Im planning to get 3 phase at my own house, And I want 100A per phase. Which is available in my area even on residential rates. I need a mains cable and switchboard upgrade anyway. So might as well do it properly.

laspaz, Dec 9, 3:56pm
Thanks for this latest info guys, I really appreciate it and it gives me a path to follow.