House Electricity

Howard H. · Jan 31, 2012

A friend of mine is putting a new house in somewhat less than a half mile from the pavement & current electrical service.

There isn't any three phase out there, and the rep from the electric company said it would be "iffy" to lay underground aluminum line that far for 220volt house service.

Isn't that purely a function of how large a diameter conductor is placed??

We've run 440volt 3 phase for center pivot sprinkler service much further than 1/2 mile, so I can't really see what objection the power company would have - other than they wouldn't be selling him $20,000 or whatever (they haven't quoted a price, yet) worth of overhead line to place a transformer right at the new house.

Thanks for any advice,
Howard

Texasmark1 · Jan 31, 2012

I don't know about underground as I haven't seen any, but around here all airborne utility service provider wire is alum. No reason submerged wiring wouldn't be alum sized appropriately, given the current price of copper.

My EE books quote wire sizing for a 2% line drop at full load and certainly distance is part of that as is wire resistance at the temperature of the delivery for the distance specified.

With all things equal, alum is usually the next wire size larger than what a copper wire would be, to carry the same continuous peak load at the same temperature.

Problem with 3 phase is that it is not made for single phase or 230V appliances so this whole thing sounds totally absurd to me!!!!!

Other than ground ref, it doesn't use a neutral and even though the individual legs are 115v (phase-n), (with no current carrying neutral per se) phase to phase is 120 degrees and not 180 degrees so the voltage is 208, not 230 and is low for single phase 230 volt appliances.

Got a current edition of the NEC?

HTH,

Mark

John T · Jan 31, 2012

Heres the deal, yes the bigger the cable the less voltage drop buttttttttttt if the distance is too great the utility may be reluctant to lay so much larger then the standard cable they normally use due to expense or its just not practical (that can mean way more expensive). Of course the same size copper has less resistance (less voltage drop) then aluminum but its more expensive.

The thing is it can be done if the wire is big enough relative to the length of the run but getting them to do it is another matter (impractical and expensive and just NOT how they do it) and, of course, theres heat energy wasted in a long run of cable from their transformer to the meter.

That is a longgggggggggggggg run for the secondary, it would likely be more efficient if they ran HV primary to near the home with a normal length of a secondary drop

A half mile is an awfullyyyyyyyyyyyyy longgggggggg run for LV secondary

John T

John T · Jan 31, 2012

Heres the deal, yes the bigger the cable the less voltage drop buttttttttttt if the distance is too great the utility may be reluctant to lay so much larger then the standard cable they normally use due to expense or its just not practical (that can mean way more expensive). Of course the same size copper has less resistance (less voltage drop) then aluminum but its more expensive.

The thing is it can be done if the wire is big enough relative to the length of the run but getting them to do it is another matter (impractical and expensive and just NOT how they do it) and, of course, theres heat energy wasted in a long run of cable from their transformer to the meter.

That is a longgggggggggggggg run for the secondary, it would likely be more efficient if they ran HV primary to near the home with a normal length of a secondary drop

A half mile is an awfullyyyyyyyyyyyyy longgggggggg run for LV secondary

John T

gene bender · Jan 31, 2012

Sounds like thats BS we have a local electric company thats putting all their main lines under ground. drive down the road and there arent any poles. The company im on will let you put wires underground. We had a place in the MTNS in the Gunnision,Colo area and it was all underground.

pat sublett · Jan 31, 2012

What is the need for 3 phase. 440 requires half the size wire as 220. The power co is right. They need to run the primary 7200-12000v closer. Also remember that wire in the ground or in conduit will carry only about 80% of what a wire in open air because of the heat dissapation.

Dblair · Jan 31, 2012

had a price given me for electricity . 1.2 miles of the nearest pole all underground 19k .

Bob from Australia · Jan 31, 2012

I wish it were that price here. We are a little over that distance and were quoted just under $100,000 for overhead wires in clear, flat country.

I concluded that the utility (it is a monopoly) just did not want to do it.

I ended up with a solar/generator system that cost about $12,000. It works well.

(Ausie$ is about on parity with US$)

RayP(MI) · Jan 31, 2012

If you think overhead is expensive, check out burried... Power company just finished some upgrades on our line, (WAY over due.) New poles, cross arms, new transformer, new drop line. They quoted me $7.50 a foot for burried line. I opted to keep it overhead.

Pole in our yard was stamped 1957, (If I could read it properly,) and most of the poles they replaced were far older than that.

buickanddeere · Jan 31, 2012

There is must be more info or something that was Ommited?

buickanddeere · Jan 31, 2012

There is must be more info or something that was Ommited?

Dblair · Jan 31, 2012

I use generator and solar cells with batteries .

MarkB_MI · Jan 31, 2012

Nobody in their right mind would try to run 240V 200 amp service for half a mile. The cables would need to be enormous. His transformer has to be much closer. I don't know the practical limit, but it's in the tens, not hundreds of feet. So to run underground, I think it would be 12.5 kV, and high voltage underground cable is not cheap.

usetob · Jan 31, 2012

they ran service(220) a lot further than that for rice wells, so I don't know the logic?

Greg K · Jan 31, 2012

When I was in apprenticeship class they were teaching us about voltage drop. Just out of curiosity I figures out what it would take to run a 100 watt bulb at the end of mom and dads 1/2 mile long driveway. The number I came up with was just about the same as the size of wire that I would use to run a 200 amp service! The power company is telling the truth. If I remember right the equation is something like, 2 x length x resistance x ampacity / circular mills of wire= voltage drop, which is 2% for branch circuits and a total of 5% for everything including the service. so if your length is 2500 feet roughly and you are using direct bury aluminum wire which has a rough resistance of 21 and the voltage is 120/240 single phase and the service size is 200 amps that would work out to be about 1,750,000 circular mills. Which means that you would have to run parallel 1 million circular mil wire, which is possibly not made, and is probably about 1 1/2" thick. This is just a rough idea but gets the idea across.

paul · Jan 31, 2012

'Here' the REA supplies overhead to your yard, high power. Ends up costing you $400 or so for fees and costs, but distance down your driveway isn't normally an issue.

A few years ago, they offered to do underground for 50 cents a foot. Obviously below cost, but they have so much less issue with trees and such, that it works for them.

Something is getting lost here, if you are choosing between 3 phase and 220v service....

Typically they run in the high votlage line - some 4000 or 7000 or more voltage just as goes past on the road.

They set a transformer in your yard, and 220 comes out of the transformer.

Typically the high votlager part is done for cheaper by the utility company, if not free, and all the 220v from the meter on is your cost.

To run a 100 amp set of 220 wires a 1/2 mile, you would need:

1000 MCM copper wire.

or

1750MCM aluminum wire.

Those are fat wires, 3 of them.

The high voltage service should be 2 thin wires, much cheaper to put the transformer in the yard rather than out on the road.

---->Paul

MarkB_MI · Feb 1, 2012

Here in the US, power to rural areas is typically delivered by cooperatives created under the auspices of the Rural Electrification Administration. Although they're still monopolies, they operate under different rules than the commercial electric utilities. Were it not for the REA, which was created back in the 1930s, large parts of the US would still be without electricity.

House Electricity

Howard H.

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Texasmark1

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John T

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John T

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gene bender

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pat sublett

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Dblair

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Bob from Australia

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RayP(MI)

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buickanddeere

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buickanddeere

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Dblair

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MarkB_MI

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usetob

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Greg K

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paul

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MarkB_MI

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