Q for sparkies - new supply

[pibby]

Any sparkies out there? On my property I'm looking at putting 240v on.

The following details are what came back from the power company about what they will do.

On the road is a pole with 15kva which services a single residence which will be replaced with a 50kva tf (split phase). From here they will install a pole on my property boundary and run across to this pole. What is split phase? Sparky wont explain it to me.

From this pole to the residence is about 330 metres which will be underground.

Will this be 415 volt or 240 v? The sparky I've engaged said will be the higher but unfortunately is not prepared to discuss any details with me. I've never used him before and at this rate probably won't if his lack of ability to provide any sort of customer service continues.

I was thinking i could get them to string the power further into my property (don't think they will) or I would put in my own pole which they can string across to from their pole on my property boundary. The aim of this is to reduce the distance of the run underground as it is getting up there. I looked up some tables for sizing and it appeared the less distance the better with smaller cable sizes.

The sparky said I can't install my own pole. Is this correct? I've put my own poles in before. Without my sparky being willing to discuss any of this I don't know what my options are and at face value the comparative costs of each of the options.

What amps do people normally aim for when supplying a house with a typical shed where the odd bit of welding, playing around with power tools? The house side doesn't exist yet but will be wood heating but oven and hot water don't know yet.

This is in tassie and you've got to pay $500 for them to provide a report on whether they can put power on for you and the cost. Unfortunately the guy at the power company seems to be mates with the sparky I was using so don't trust what I'm being told. Told them I'm the property owner and they need to at the very least communicate with me and discuss the options. Didn't go down too well but last I heard I am the customer and this will be costing me a few bob so chin up to them.

Appreciate any advice here.

Thanks,
Brett.

[Aaron IIA]

If you want single phase, it will be 240V. If you want three phase, it will be 415V.
As far as putting in your own pole, as far as I know you can't.
If you are going single phase, you would probably want at least 100 amps.
Aaron

[Eevo]

Sparky wont explain it to me.

is not prepared to discuss any details with me.


Without my sparky being willing to discuss any of this



don't trust what I'm being told.

Didn't go down too well


i cant answer any of your questions but i can tell you to find someone else.
with tradies like these, extras will creep in and you will end up paying double.

[p38arover]

I think I'd be looking for a new electrician.

I'm no elec but I'd recommend a 3 phase (415v) supply if the supplier will agree. It's not going to be cheap but you'll not regret it.

There's a saying that you only remember what something costs when you're dissatisfied with end result (something along those lines) - and, from years of experience, I can tell you that's true.

[pibby]

They can't get 3 phase up to my end of the street. That's where the split phase (2 phase) comes in. I don't know what it is but sparky said its the 400 odd volts so will help keep size of cables down. So if its 400odd volts is there a transformer put in at my house?

Still not convinced I can't put my own pole in, I've done it before.

[scarry]

Like Ron said,if they can't tell you exactly what they are doing,move on and find another sparky.It is your mains,and you will be paying towards it.

That is a long way(over 300m),needs to be done right or you will have issues later.

Usually the run is either 415v 3 phase or 240v single phase.
Occasionally they would run two phases,but this may not be done anymore.

Edit,just saw your post above.

Two phase is just like two single phases,instead of one large single phase cable.
The single phase load is then balanced on the two phases,using a neutral,is just two 240v cables.

You can't run any 3 phase gear on two phases.

Although just to confuse everyone,in our game,refrigeration,we do use two phase 415v motors,but i haven't seen them used anywhere else.

[Vern]

I do a lot of two phase underground jobs, it is just 2x240v, so 480v. Due to bushfire regs, all services must be underground now, hence no poles.
Have you looked into running aluminium conductors? At a guess it would be 120mm2 , a bit bigger but a 3rd the cost of copper. Pay the $500, its to confirm the cost of what they have to do and sometimes the only payment you have to make. Transformer will be left outside your property.
If you think your sparky is ripping you, pm me and I can shoot you some costs.

[JDNSW]

... Due to bushfire regs, all services must be underground now, hence no poles.
.....

Victoria only, I believe, but expect this trend to increase elsewhere.

John

[Vern]

Probably correct john, I only work in vic so only know those regs.😊

[Owl]

When you get the supply on, have a single phase 480V outlet in your shed.

You can get welders with bigger capacity than your average 240V models. You can also get 480V single phase motors for powering larger compressors etc.

[pibby]

Thanks for replies. trying to get my head around the basics before I jump into the specific $ then will look at that side. (Vern - already paid the $500)

The split phase is treated as 415v and allows approx half the size cable? How many cables in total?

The pole on the street with the 50kva is 16 metres from my boundary where they will put my pole. if they aren't prepared to put that pole further into my property
- is it allowable for me to put my own pole in further into my property to take the span from the pole on my boundary?
- is the max span between the poles approx 40m which is what I'm being told?

Cheers.

[Owl]

..... The split phase is treated as 415v and allows approx half the size cable? How many cables in total? .....

Cheers.


Not 415V. It will be 480V.
3 cables involved.
240V(1)-Neutral-240V(2)

There are two phases here. The first is taked from 240V(1)-Neutral and the second from Neutral-240V(2). These two phases will be distributed around your house so that the load between the phases is approximately equal.

The 480V for your shed is taken by wiring between 240V(1) and 240V(2).

My dad had this arrangement on his property. In his case, the supply authority placed the pole with the transformer ~20m from the house. This was in the 1970's, so regulations may have changed since then and state regulations probably vary. I also recall it cost him a packet to have it done!

[Blknight.aus]

Split phase can get you an effective 480v supply. Think industrial single phase 415

It can also give you two phases of 240v.

It's done because it's cheaper to run any distance and then put a transformer in for standard domestic.

You can't get three phase from it.

No, you can't put you own pole in but that only counts for the first pole from the transformer of if the transformer is on a plow on your property the pole the transformer is on. After the fuses as long as you run to code you should be Apple's

Not that you probably couldnt do it better than the mob that will get paid a mortza to do it, you just can't sign the bit of paper because your not qualified.

Your mialage on this info may vary. Its lunch time and i just asked the sparky whose car I'm doing the timing on*.

[Vern]

Pibby, what are you trying to achieve by having a pole?
Put it all underground, get it all out of site, less damage can occur then.

[pibby]

Pibby, what are you trying to achieve by having a pole?
Put it all underground, get it all out of site, less damage can occur then.

Vern - trying to understand if I can get an additional span in above ground to reduce the underground sizing/distance. When I checked the sizing last time for 240v using 10% voltage drop I was comfortably able to drop a cable size if I got it down to say 280m. Without doing the $calcs I was trying to understand if I could put a pole in and if so I would then check the $ equation. If I had to pay someone I wouldn't consider it. Now it's going to be this split phase 480v I'm trying to understand what it does to the cable sizing too.

I am not sure if I'm being sold a pup with the solution the power company and the sparky have put together as adjacent to my entrance is a house which the sparky and the guy at the power company seem to be doing everything to look after their interests with the placement of the pole, I know the sparky has done work for them before but not me.

The entrance to my block is 20 metres at the road then 250 metres deep where it has opened to 30 metre wide. By this stage the forest starts, before that it is pasture. I'm then another 180 acres of forest behind this so I don't want overhead anywhere near that but I don't have a problem for the start of my entrance.

[Vern]

No more than 5% volt drop.
They will only supply power TO your property, from there on its your problem.
480 (2 phase), you can reduce the cable size as you are spreading the load over two phases.
Are the cables to be dressed up the pole, or are they putting a pit in for you?
Run it in aluminium as I stated earlier to reduce costs (about 60% cheaper in cable cost), as I said, from past jobs I've done, I'm guessing 120mm2 .

[Aaron IIA]

What cross sectional area cable have you been doing your calculations with?
Aaron

[BadCo.]

GenCalc says 120mm2 copper or 185mm2 Al for 100 amps at 280m.

Let me know if you want other crap calculated.

Dunno what this two phase poo is, must be a rural thing? I have never heard of '480v' and our countries share mostly the same rules

Also something to consider is the power company may charge you extra each month for having three phases over the normal two.

As others have said, get another sparky. Something there doesn't seem right.

[Vern]

GenCalc says 120mm2 copper or 185mm2 Al for 100 amps at 280m.

Let me know if you want other crap calculated.

Dunno what this two phase poo is, must be a rural thing? I have never heard of '480v' and our countries share mostly the same rules

Also something to consider is the power company may charge you extra each month for having three phases over the normal two.

As others have said, get another sparky. Something there doesn't seem right.

Your calcs are for single phase, my guesstimate is split over two phases, if running two phase, who is going to use 100a per phase? Split the load.
Yes its a rural thing, he will have a swer line I presume, they can take a second tap from the transformer to produce 2x 240v, or he has a 2 phase transformer across the road.

[Vern]

What cross sectional area cable have you been doing your calculations with?
Aaron

I just use my cable calc programs these days, been a looooong time since I have done it the old fashioned way:) not even sure where me as/3008 is anymore:(

[BadCo.]

Your calcs are for single phase, my guesstimate is split over two phases, if running two phase, who is going to use 100a per phase? Split the load.
Yes its a rural thing, he will have a swer line I presume, they can take a second tap from the transformer to produce 2x 240v, or he has a 2 phase transformer across the road.

It was for three phase actually, and was only done as an example as I saw 100a and three phase being talked about.

Single phase 100a would be a 500mm2 cu or 400mm2 ALU which is ridiculous for a house haha

For arguments sake if you went three phase 32a it would be a 70mm2 cu or 120mm2 Al. Unbalanced of course.

Maybe you should whip out your calc app and see what your split phase tells you.

Definitely agree about using aluminium conductors, so much cheaper and modern aluminium cables aren't too bad to work with.

[BadCo.]

I just use my cable calc programs these days, been a looooong time since I have done it the old fashioned way:) not even sure where me as/3008 is anymore:(

Same here, it's too easy to use an app these days. Much faster if you have to do the volt drop for a ton of cable runs on a job.

[BadCo.]

Sorry double post.

[Vern]

Sorry your right, had way to many :beer: today.
I have just been guessing, I need to punch it into the computer when in the office next. Would like a good phone app though.
I use aluminium a bit nowadays, much easier, lighter, and cost effective, and the new bimetal lugs make it easy.

[BadCo.]

Sorry your right, had way to many :beer: today.
I have just been guessing, I need to punch it into the computer when in the office next. Would like a good phone app though.
I use aluminium a bit nowadays, much easier, lighter, and cost effective, and the new bimetal lugs make it easy.

Shear bolt bi metal lugs are awesome, so much easier then using the 12 and 60 ton crimper and there associated dies.

As for app, look on the play store for GenCalc, made by General Cable. It costs a bit but definitely worth it.

Edit. Link attached
https://play.google.com/store/apps/details?id=com.generalcable.gencalc
https://itunes.apple.com/nz/app/gencalc/id725309423'mt=8

[Vern]

The mob that I get my cable calc program from may do an app.
Yeah I only use the shear bolt ones, prior to that it was hand crimper, what a bugger that was, and messy:(

[pibby]

ok heard back from guy at tasnetworks (power company). it seems i am allowed to install my own pole on my property (obviously to standard). sparky is definitely playing funny buggers saying i cant so i'll be looking for another one.

tasnetworks say can span upto 35 metres from their pole on the street side of my boundary to my pole i put in but they will supply the span for free.

so next question what is impact this 35 metres less for the wires to run underground has on their sizing. im guessing it will bring it down to the 280-290m. is there a website people use which has trustable figures which give you cable size? then i can be in some position to work out if putting the pole in is economically worthwhile.

vern - there is no talk of a pit, it says they will install 2 LV fuses 80A to the pole. the 10% voltage drop was what sparky told me, i thought it was 5% allowed to the house and 5% within myself but its not the first bit of dud info he's given me. once i get a sparky will enquire on the use of aluminium cable too.

[Vern]

You seem adamant on having a pole to save you probably $500, that pole is and will be your responsibility for ever, I personally would go underground the whole way. Have you had a price on the cable yet?
Have you considered supplying and laying it yourself? Its not a great job:)
I'm not up on tassie's requirements, but we can only go straight to a pole if its on private land, other wise a service pit must be installed at the property boundary.

As I said, get me a fairly close distance, and I can let you know what cable to use, and even get a cost.
Where is the said property?

[pibby]

vern - i'm down the bottom of tassie, well past hobart.

yeah regs must be different here. my neighbour has the same setup i am talking about but only half the distance to cover - ie pole on boundary to private pole then underground to house. i've done this exact setup before too.

i'm not determined to put the pole in, now that i know it is still possible and i am allowed to put it i can run the ruler across the equation to help in the decision.

as for exact distances, as the crow flies it is 298 metres. but i am adding 30 metres on to it as it is rises up a hill. so that's where i come up with 330 metres. now if the pole goes in it gets 35 metres taken off it!

i am not in tassie at the moment to run a wheel across it.

last place i had i helped the sparky run 130 metres underground which had a few bends and some right angles in it so was a bit painful. this might not be much worse as it is pretty much a straight line aside from the vertical element which may help. i've got my own excavator so i'll dig the trench myself or get my neighbour to so cost is next to $0 aside from materials.

[Vern]

Dover, south port area?

Well if you have your own machine, lay it yourself:)
With those figures I can let you know what size, will work it out tomorrow. I will work on 300m, now I'm thinking minimum 150mm2 or 185mm2 in aluminium and probably 80mm conduit.

[BadCo.]

What are your regs for burying cables? Over here it is 600mm deep with a layer of dirt and then danger tape. I presume it's the same in Australia?

[Vern]

Yep, same. I completely forgot about this thread, been to busy in my own little world. Will size it up when in the office next (if I remember):(

[pibby]

ok, after the rush of responses to calculate the cable size i've downloaded 'gencalc' to have a few guesses. :p

put in 40A current per phase (interpreting forum responses is this correct so in total 80A for the two phases in total?)
voltage 240v
5% voltage drop
330m run of cable
single core
underground in single duct
single phase


it comes up with min size 50mm Cu (70mm Alu) which i need 2 of plus neutral (same size?)

or do i put it in as 480 volt which for for 80A comes up same size Cu cable but Alu goes to 95mm?

or third, i've got no idea what i'm doing?

[Vern]

Back in 20!

[Vern]

OK, I punched in,
330m
4% volt drop
480V
100A
100Amp c/breaker
buried in conduit
XLPE


70mm2 copper (x3)
95mm2 aluminium (x3)


I wouldn't go any smaller personally.
:)

[pibby]

cool !

service with a smile :)



what size conduit will they fit in?


thanks vern. now i can have a look at the $ :o

[pibby]

some rough numbers just for cable costs :

70mm say $9.9 metre
70mm XLPE COPPER [XLPE70] - $11.00 : Electrician Supplies, ready and available for you online right here (http://www.electriciansupplies.com.au/shop/index.php'main_page=product_info&cPath=26_68&products_id=967)

cable cost $9801 for 330 metres

50mm say $6.6 metre
50mm XLPE COPPER [XLPE50] - $7.70 : Electrician Supplies, ready and available for you online right here (http://www.electriciansupplies.com.au/shop/index.php'main_page=product_info&cPath=26_68&products_id=966)

cable cost $5841 for 295 metres + say $600 for pole = $6441

difference $3360 so not worth sneezing at if get a pole put in to reduce span

caveat - dropped amps to 80A and voltage drop to 4.1% from vern's figures so kinda shows there's merit in looking at the pole option. i'll have instantaneous gas hot water, gas hot plates and wood heating so have to understand if 100A a necessity. anyway will now have to find a sparky who can actually communicate and discuss options! :)

thanks for responses vern & everyone else.

[Vern]

Aluminium I say, would be 1/3 the cost. Actually I have my price for th 95mm on my computer, I bought 660m of it the other day. However I would prefer to pm you the cost.

[Rurover]

Pibby,

Not wanting to derail your deliberations, but why not drop the idea of connecting to the grid and install a stand-alone system based on solar and maybe a small wind turbine.

Not sure what you pay for power and connections in Tassie, but in SA, it's often cheaper to install solar and battery backup rather than pay for bloody expensive poles and/or underground cables, then pay more than 30 cents per kWh thereafter.

Strongly suggest you get a quote from a reputable (and communicative!) solar installer to see what the price comparison might be. The panels are now very cheap, and prices for Lithium Iron batteries are falling steadily. They're virtually maintenance free compared with the old battery technology.

Good ,luck,

Alan

[Vern]

Pibby, I can quote that for you as well😊. Seriously, to be done properly, it will be more than 3 times the cost of going on the grid, and a lot more headache.
My motto for stand alone customers is "a friend for life".

[pibby]

vern - interested to see how aluminium stacks up so feel free to pm. is there any other regs covering alu or disadvantages (aside from bigger conduit) as no one down here has mentioned it.

ruover - this place i will probably be selling in a couple of years so my main thinking is i'll significantly restrict the market who would look at buying it if i went solar. i lived in middle harbour in middle of sydney for couple of years on my old yacht, coming home to a candle and metho stove each night so not averse to other ways of doing stuff. at this same property i have two other titles which have no chance of getting power to.

i'm still not fully signed up to solar other than a couple of panels to run lights which i am doing now. a gas oven, gas fridge, gas/wood hot water will provide me what i need with a 9kva generator to run stuff as needed.

i keep reading up on solar but i just feel i dont want to spend my time staying on top of batteries, having to have a generator anyway, what if there's a week of bad weather in middle of winter, one of the cells in the batteries goes tits up etc just prefer set and forget and able to walk away and walk back whenever without thinking about power generation.

i dont have more experience than my couple of panels but these are the sentiments i pick up from reading other's experiences. thanks for the prompting. :)

[dero]

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 .

[dero]

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 .

[pibby]

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).

[dromader driver]

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.

[Vern]

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.

[dromader driver]

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.

[Vern]

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

[BadCo.]

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

[Vern]

Exactly bad Co, who want to buy a property where you can't run machinery because the incoming supply is too small.

[pibby]

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

Good point. Agree, sometimes to save one dollar can cost you two.