Need advice on running an electric transmission line to a new home

[spidermike007]

I am going to be building a home in the provinces sometime soon. We need to run an electric line about 1.2 km, from the main post. There is a major transformer about 50 meters from that post. We may eventually have another home and a small building on the land, for a fruit operation. What is the largest line we can run, without getting the electric company involved? Would the use of 10cm. metal posts (six meters tall, sunk in one meter with a concrete footing) be recommended for the transmission line? Can we get away without the need for a small transformer? Any advice is appreciated. We are looking to do good work, that will stand the test of time, without spending a fortune. And as you can tell, electrical work is not my area of expertise! An electrician will be doing the actual work. Thanks.

[Crossy]

Is all the run on your land or it is public roads? Where will the meter be positioned?

 

1.2km is looong way to run 220V, you are looking at some pretty big cables. I'll do some sums later.

 

Concrete poles are the norm here, they're cheaper than steel and don't rust.

 

 

[Fruit Trader]

1 hour ago, Crossy said:

Is all the run on your land or it is public roads? Where will the meter be positioned?

 

1.2km is looong way to run 220V, you are looking at some pretty big cables. I'll do some sums later.

 

Concrete poles are the norm here, they're cheaper than steel and don't rust.

 

 

Even for a bad 10% loss at 20 amps the cable size would most likely exceed 50mm.

I would call in a power line sub contractor and prepare for some bad news. 

[mogandave]

At that distance the wire might pay for a dedicated transformer

[farmerjo]

These days i doubt the PEA will let you have a meter over that distance without their poles and cable.

Over 10 years ago we ran power 800 metres,to get the meter connected we borrowed some land close to the last pole,built a sala with light,switchboard and ground rod.They came and inspected and connected.Then we ran poles 33 metres apart 1 metre off the side of road to home(25sq cable).Things were a little more relaxed back then as original house was already built and inhabitated and we were given a house meter(15/45).Power varies from 150 volts to 230 but in general besides trying to start things like a deep bore pump(which we bought a variac for) it's been ok.The fridge from start rattles a bit but had no real appliance failures.  Hot water system is the weakest point.

As time has gone bye we have removed 200 metres of poles and put meter closer as demand in area has grown.

As it stands now  its opening up a can of worms as neighbours between me and last pole have been offered temporary only meters that come at a higher running cost unless the PEA does the work.They can apply for government grants for power which they are doing. 

On the poles,i have locally made concrete reinforced 5"x5" 7 metres tall,1 metre cemented in the ground(1500 baht each).Minimum required height was 5.5 metres above ground. Hope this helps.

Edited June 12, 2018 by farmerjo

[stud858]

I'd be interested to know how strict things are in regards to following safety and specs and how bothered the authority is with the job other than the usual mai pen Rai comments when skimping on quality standards.

I mean all you have to do is walk around town with your head up to see the wired jungle. 

I'm guessing there's a few electricity line pinchers in the mix too.

I'd get some companies to do their quotes but double check with google searched forums specific to electrical engineering to confirm it is good. 

Edited June 12, 2018 by stud858

[Crossy]

14 hours ago, Fruit Trader said:

Even for a bad 10% loss at 20 amps the cable size would most likely exceed 50mm.

I would call in a power line sub contractor and prepare for some bad news. 

With 1200m @ 20A & 5% drop Doncaster Cables calculator http://www.doncastercables.com/technical-help/ wants 120mm² copper (say 185mm² aluminium), a pretty big cable by any standards.

 

How big is the house? What's your expected load (aircon, water heaters mainly)?

 

As mogandave suggests, this is not going to be a cheap job and it's likely going to be best to run the HV (25kV) to your property and have a dedicated transformer, it's certainly going to deliver a more stable supply.

 

Time to have a chat with PEA methinks, ask them what the options are.

[mogandave]

With 1200m @ 20A & 5% drop Doncaster Cables calculator http://www.doncastercables.com/technical-help/ wants 120mm² copper (say 185mm² aluminium), a pretty big cable by any standards.
 
How big is the house? What's your expected load (aircon, water heaters mainly)?
 
As mogandave suggests, this is not going to be a cheap job and it's likely going to be best to run the HV (25kV) to your property and have a dedicated transformer, it's certainly going to deliver a more stable supply.
 
Time to have a chat with PEA methinks, ask them what the options are.

I’ve only worked with the PEA a few times, but it’s always been easy and they’ve always treated us right. Also, i believe if they do it, and it has to be moved in the future they’ll make it right.

Something to be said for easy, particularly when the wheels can fall off the job anywhere along the way...

[reargunnerph3]

Never, ever use steel poles for electrical work. Steel reinforced concrete poles with either hard wood or cement cross arm or hung vertically down the pole on brackets and insulators. Get a professional to do it. Electricity is deadly. Ex Electrical Linesman.

[Fruit Trader]

15 minutes ago, reargunnerph3 said:

Never, ever use steel poles for electrical work. Steel reinforced concrete poles with either hard wood or cement cross arm or hung vertically down the pole on brackets and insulators. Get a professional to do it. Electricity is deadly. Ex Electrical Linesman.

[Crossy]

2 hours ago, reargunnerph3 said:

Never, ever use steel poles for electrical work.

I've never seen anything other than steel used for the supports of the OCS (overhead collection system) on railways anywhere in the world, usually 25kV or so.

 

That said, concrete is the go-to material for power distribution, it's cheap and long lasting (and a fair to middling insulator when dry).

[oobar]

We built our rural home exactly (and coincidentally) 1.2km from the nearest transmission line on the main highway.   The PEA ran high-voltage lines, three-phase, to our house, and a contractor did the work from there to our panel.   Like others, I think the distance is a bit far for 220 volts.  The transformer required for a living area of about 300 square meters with eight air conditioners was not cheap, and the total cost for everything, including poles, ran about 500k.

[stud858]

3 minutes ago, oobar said:

We built our rural home exactly (and coincidentally) 1.2km from the nearest transmission line on the main highway.   The PEA ran high-voltage lines, three-phase, to our house, and a contractor did the work from there to our panel.   Like others, I think the distance is a bit far for 220 volts.  The transformer required for a living area of about 300 square meters with eight air conditioners was not cheap, and the total cost for everything, including poles, ran about 500k.

500,000 baht. 

I think that would get you an excellent off grid solar system.

Batteries,  backup generator + Solar water heater. 

 

 

 

[reargunnerph3]

15 hours ago, Crossy said:

I've never seen anything other than steel used for the supports of the OCS (overhead collection system) on railways anywhere in the world, usually 25kV or so.

 

That said, concrete is the go-to material for power distribution, it's cheap and long lasting (and a fair to middling insulator when dry).

A bit hard to build train or tram overhead power lines with concrete? Hi voltage transmission lines also made of steel because there is no option.

[reargunnerph3]

18 hours ago, Fruit Trader said:

Low voltage consumer power poles are made of hardwood or concrete. High voltage transmission lines and train or tram lines are steel because it's impossible to use anything else.

[mogandave]

Low voltage consumer power poles are made of hardwood or concrete. High voltage transmission lines and train or tram lines are steel because it's impossible to use anything else.

They use aluminum in the US sometimes

[Fruit Trader]

1 hour ago, reargunnerph3 said:

Low voltage consumer power poles are made of hardwood or concrete. High voltage transmission lines and train or tram lines are steel because it's impossible to use anything else.

But you said never ever use steel poles for electrical work and now you are saying its impossible to use anything but steel for high voltage lines.

 

230 KV wood transmission towers

 

[spidermike007]

17 hours ago, oobar said:

We built our rural home exactly (and coincidentally) 1.2km from the nearest transmission line on the main highway.   The PEA ran high-voltage lines, three-phase, to our house, and a contractor did the work from there to our panel.   Like others, I think the distance is a bit far for 220 volts.  The transformer required for a living area of about 300 square meters with eight air conditioners was not cheap, and the total cost for everything, including poles, ran about 500k.

That is very helpful. So far the PEA said they would not run the lines for only one home. They told us we would have to do it ourselves. There is a substantial village transformer about 50 meters from the post, that we would be running the line from. Do you think we would need our own dedicated transformer? What do they cost? There is a chance we may eventually build a second or maybe even a third home on the land, for some friends. But, that is way down the road. For now, I assume we will need up to 10,000 watts of power, for refrigerators, freezers, washer and dryer, computes, electronics, water pumps, lighting, and at least three or four AC units, etc. We are looking at about a 300 square meter home. 

[reargunnerph3]

11 minutes ago, Fruit Trader said:

But you said never ever use steel poles for electrical work and now you are saying its impossible to use anything but steel for high voltage lines.

 

230 KV wood transmission towers

 

Transmission Lines. These are High Voltage but not Transmission Lines and it's probably America anyway they always find a way to <deleted> up a good story.

[spidermike007]

On 6/12/2018 at 12:35 PM, Crossy said:

Is all the run on your land or it is public roads? Where will the meter be positioned?

 

1.2km is looong way to run 220V, you are looking at some pretty big cables. I'll do some sums later.

 

Concrete poles are the norm here, they're cheaper than steel and don't rust.

 

 

Most of the run is in front of farms, where there are no homes. It is a small rural, gravel road. That info would be helpful. Thanks.

Edited June 19, 2018 by spidermike007

[spidermike007]

17 hours ago, stud858 said:

500,000 baht. 

I think that would get you an excellent off grid solar system.

Batteries,  backup generator + Solar water heater. 

 

 

 

Not from what I understand. I am told for 500,000 it would be a minor passive system, incapable of running three or four AC units. Also, there are many cloudy days, as it is a stormy area. 

[Crossy]

23 minutes ago, spidermike007 said:

For now, I assume we will need up to 10,000 watts of power, for refrigerators, freezers, washer and dryer, computes, electronics, water pumps, lighting, and at least three or four AC units, etc.

10kVA comes out at 45A on a single-phase supply.

 

Going to my friends at Doncaster cables gives us (for 1.2km):-

Quote

"We were unable to calculate a recommended cable size for this application. Please check that your requirements are correct and try again"

Which implies that there is no practical solution.

 

If you went 3-phase on a 15A supply you could use 4 x 50mm² but at only 15A per phase you are going to have fun balancing up the load.

 

I strongly suspect you are going to be paying for 1.2km of HV poles and a 20kVA transformer ?

 

Or you could look at a 20kVA diesel generator, at least in the interim, that would give you enough power but at the expense of ongoing fuel costs.

 

[stud858]

18 minutes ago, spidermike007 said:

Not from what I understand. I am told for 500,000 it would be a minor passive system, incapable of running three or four AC units. Also, there are many cloudy days, as it is a stormy area. 

Yeah could go either way.  I haven't sat down and crunched the figures for panel, inverter and installation costs in Thailand.

Cloudy does not necessarily mean loss.  From looking at my inverter I'm surprised to see just as much power on the LCD reading as a bright day.  The uv radiation that hits the Panels still get through.  Just like you can get sun burn on a cloudy day. 

 

[mogandave]

Maybe someone at the PEA can help you select a contractor.

Trying to do this yourself over someone else’s lane will likely not end well.

I would try going to the PEA again...

[oobar]

6 hours ago, spidermike007 said:

That is very helpful. So far the PEA said they would not run the lines for only one home. They told us we would have to do it ourselves. There is a substantial village transformer about 50 meters from the post, that we would be running the line from. Do you think we would need our own dedicated transformer? What do they cost? There is a chance we may eventually build a second or maybe even a third home on the land, for some friends. But, that is way down the road. For now, I assume we will need up to 10,000 watts of power, for refrigerators, freezers, washer and dryer, computes, electronics, water pumps, lighting, and at least three or four AC units, etc. We are looking at about a 300 square meter home. 

If you are going to run 220V lines from a nearby transformer (which is shared with others), you would not need a second one at your home, because the voltage has already been stepped down for home use.   All you would need is a meter.   That's entirely different from what we did.   We paid to have PEA bring the high-voltage lines to our location, and the voltage was stepped down there by a transformer that we also paid for.   You will have  voltage drop with only 220V over 1.2 km, and it may not be adequate for your home needs.  And there can be disadvantages in sharing transformer capacity with others.  During construction, we used a km or more of insulated 220V from a shared transformer, and it was nowhere near adequate for what our completed house requires.   I assume PEA will run high-voltage lines to your site, since they did for us.  You just have to pay.  For a 300 sq meter house, at least where we live, I don't think a shared 220V is the way to go.

[Crossy]

Some important points to note (most are already in this thread anyway).

 

If the road is not yours then you will need easements in order to run your poles. PEA are  (should be) skilled in obtaining said permissions.

 

You could run HV poles down the road and have a local transformer - This is the ideal (but potentially most expensive) solution, if further properties are likely to be built along the route it may be possible to strike a deal with PEA for a co-payment.

 

If you want to run 220V (cheaper poles but fatter cables and no transformer) you will need, for a single-phase 10kVA supply and a worst-case 10% (22V) volt drop a total cable resistance of about 0.5 Ohms. So for 2.4km (out and back) that's .21 Ohms per km. That's going to be 95mm² copper or (cheaper and less likely to go walkabout) 150mm² aluminium. Your contractor (PEA) needs to confirm these sizes before you buy anything.

 

EDIT You can get an idea of cable costs from SK Universal http://www.sk-wires.com/en/  their English speaking contact, k. Bell, is extremely helpful.

 

[spidermike007]

17 hours ago, oobar said:

If you are going to run 220V lines from a nearby transformer (which is shared with others), you would not need a second one at your home, because the voltage has already been stepped down for home use.   All you would need is a meter.   That's entirely different from what we did.   We paid to have PEA bring the high-voltage lines to our location, and the voltage was stepped down there by a transformer that we also paid for.   You will have  voltage drop with only 220V over 1.2 km, and it may not be adequate for your home needs.  And there can be disadvantages in sharing transformer capacity with others.  During construction, we used a km or more of insulated 220V from a shared transformer, and it was nowhere near adequate for what our completed house requires.   I assume PEA will run high-voltage lines to your site, since they did for us.  You just have to pay.  For a 300 sq meter house, at least where we live, I don't think a shared 220V is the way to go.

Thanks for the info. The transformer is only 26 meters from the post on the road, where we would be hooking up our electric. But, obviously that is shared with others. So, do you think we would need to have a dedicated transformer? If I was looking at enough electric for one main house, and two smaller houses down the road, would a 50 kVA transformer be adequate? Are they affordable? Or best to just try to get the PEA to do all the work? 

[mogandave]

Thanks for the info. The transformer is only 26 meters from the post on the road, where we would be hooking up our electric. But, obviously that is shared with others. So, do you think we would need to have a dedicated transformer? If I was looking at enough electric for one main house, and two smaller houses down the road, would a 50 kVA transformer be adequate? Are they affordable? Or best to just try to get the PEA to do all the work? 

I think you should go back through and read all the posts more carefully.

[maxpower]

4 hours ago, spidermike007 said:

Thanks for the info. The transformer is only 26 meters from the post on the road, where we would be hooking up our electric.........

From 1200m the only practical solution is to bring high voltage lines to your plot so I suggest you stop thinking about existing transformers. Previous posts have already pointed this out.

 

If this is not a pipe dream and you understand it could knock a decent hole in 1M Baht then ask the PEA or suitable contractor for feasibility survey and price estimate. They will answer all of your load and transformer questions along with how much capacity is available on the high voltage line.

 

[oobar]

6 hours ago, spidermike007 said:

Thanks for the info. The transformer is only 26 meters from the post on the road, where we would be hooking up our electric. But, obviously that is shared with others. So, do you think we would need to have a dedicated transformer? If I was looking at enough electric for one main house, and two smaller houses down the road, would a 50 kVA transformer be adequate? Are they affordable? Or best to just try to get the PEA to do all the work? 

Listen to Crossy.  He knows.   The most expensive route, but the best, as he says, is probably high voltage to your house, with transformer and meter ahead of your panel.  PEA will give you a cost for everything, including poles, lines and transformer.  We have three-phase, with a 50KV transformer.  One phase supplies our small workshop, another the first floor of our house, the third powering the second floor.  This was almost five years ago, so I'm not immediately sure, but I think the transformer was around 60-70K.   You'll pay for the poles -- ours were 9.5k each -- but you don't own them.  They help expand the grid for others.  The 1.2 km from the main road was only a bumpy dirt road, fronted by properties owned by a mix of people, but I am unaware of any issues regarding putting up poles.  The PEA seemed to stick them into the ground wherever they felt they were needed.