# What size wire to use running underground



## LyonsElecSupply (Jun 16, 2010)

first off lets start with the amperage of the service drop. I would anticipate nothing more than 150 from what you said, but it would be nice to know what the POCO put in.


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## LyonsElecSupply (Jun 16, 2010)

Ball parking this and going off of assumed amperage heres what i came up with:

theres a 99% chance you will go with aluminum on this as copper would be in the neighborhood of a few thousand dollars. SO if you are using aluminum you will need type USE-2 or USE
Heres the table I figured for 325 feet.

100 amps: 2/0
125 amps: 3/0
150 amps: 4/0
200 amps: 250 Kcmil (or parallel runs of 2/0) 

Although if you are doing 250 kcmil you might need 3" pvc.

These tables are calculated on a 5% voltage drop at stated amperages.

I suggest whatever amperage you choose you upsize your wire once to leave room for error. 

The problem becomes most 100 and 125 amp breakers dont accept 4/0 unless they are the molded case main breakers (not a branch acting as a main)

Most only accept 3/0

My recommendation: 3/0 aluminum URD with a 100 amp service....


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## Speedy Petey (Feb 1, 2004)

Lyons, WHERE are you getting these numbers from?

The service lateral is NOT under the jurisdiction of the NEC, it is under the oversight of the POCO. 
Normally the POCO will run, or require, "standard" wire up to 250' for secondary voltage (120/240v). #2AL for 100A and 4/0AL for 200A. Longer and they will bump up in size accordingly. 

For a 300+' run to a 200A panel 250AL would be typical.

No way I'd go with a 100A service on a new house. Not unless it was 800 sq/ft or smaller. 
200A is pretty standard right now with 320/400A becoming more and more popular/necessary.


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## Saturday Cowboy (Nov 29, 2009)

disconnect on the pole. AL wire. NEED TO DO A SERVICE CALC

Pete I think since you're required to have a disconnect at the pole it would fall under NEC, as it would be private line from the pole to the house. OP said he was only going to have the POCO run to property line. So our meter would be on that pole. In my experience most POCO consider the meter the service point.


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## Speedy Petey (Feb 1, 2004)

Saturday Cowboy said:


> disconnect on the pole. AL wire. NEED TO DO A SERVICE CALC
> 
> Pete I think since you're required to have a disconnect at the pole....


Where is this written? There is no requirement to have a disconnect at the pole.





Saturday Cowboy said:


> ..............it would fall under NEC, as it would be private line from the pole to the house.


OK, but that does not change anything, 310.15(B)(6) still applies which are the numbers I posted above.





Saturday Cowboy said:


> OP said he was only going to have the POCO run to property line. So our meter would be on that pole. In my experience most POCO consider the meter the service point.


True, but in most cases the lateral is still under POCO jurisdiction. At least here it is. It is clearly spelled out in our POCO"s guide book.


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## Saturday Cowboy (Nov 29, 2009)

Speedy Petey said:


> True, but in most cases the lateral is still under POCO jurisdiction. At least here it is. It is clearly spelled out in our POCO"s guide book.


If we put a meter on that pole, it is now not a service lateral, but underground feeder.


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## LyonsElecSupply (Jun 16, 2010)

I dont recall a disconnect being mentioned. 

However it is NOT jurisdiction of the POCO. POCO is meter and up. 

I think he will need to have a disconnect as it is too far away and is considered a feeder not a lateral.

Do a calculation on it.


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## ms66cadillac (Jan 11, 2011)

LyonsElecSupply said:


> first off lets start with the amperage of the service drop. I would anticipate nothing more than 150 from what you said, but it would be nice to know what the POCO put in.


The POCO hasn't yet installed the service drop, but it would be the typical for a homesite. I will have seperate "commercial" meter for the pole barn/shop and then one for the gate up towards the front of the property. The reason for the seperate meters, is because the POCO give 4500 credit for each meter installed. I know this will bring in more service charges in the long run, but I don't have 24,000 to drop just to get it 1400 feet to my property. 

So, I am hoping to save a little money once the meter gets to my property and run the utilities underground from the meter. Because if I don't it adds on another 300 feet from the meter to my homesite, and well I am hoping that going underground on my own will be less expensive then them putting it in for above ground. 

Now in regards to these other two meters I am going to have. One will be down at the gate, but the other I want where my homesite meter will be. My question is can you put 2 meters on one pole, or will POCO put the meters on two seperate pole. If on one pole, can I run both wires from each meter in the same conduit. The one meter is going to service my shop/shed which will be near my homesite. I won't be using any welders or anything. Just basic tools that don't run on 220 or 240, whatever it is...
An electrician is going to do this for me, but I want to make sure I am making the most economical choice, but wise choice. Is alum. wire safe to use? I hear all kinds of stories about it. I don't see myself affording copper at this time. Will aluminium get the job done?

Thanks yall.


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## Saturday Cowboy (Nov 29, 2009)

ms66cadillac said:


> The POCO hasn't yet installed the service drop, but it would be the typical for a homesite.


typical whats that?:whistling2:


ms66cadillac said:


> I will have seperate "commercial" meter for the pole barn/shop and then one for the gate up towards the front of the property. The reason for the seperate meters, is because the POCO give 4500 credit for each meter installed. I know this will bring in more service charges in the long run, but I don't have 24,000 to drop just to get it 1400 feet to my property.


come now have you talked to the POCO? do you think they're that dumb?:jester: I bet they won't count meters as much as costumers for credits? Let me know


ms66cadillac said:


> So, I am hoping to save a little money once the meter gets to my property and run the utilities underground from the meter. Because if I don't it adds on another 300 feet from the meter to my homesite, and well I am hoping that going underground on my own will be less expensive then them putting it in for above ground.


If you do the work yourself I would think you could save some money. And I recommend underground wiring vs. overhead. But once you hit that meter its all private install/maintain, and the meter has to be on the upstream side of your underground feeders save less you pay the POCO to install them.:whistling2:


ms66cadillac said:


> Now in regards to these other two meters I am going to have. One will be down at the gate, but the other I want where my homesite meter will be. My question is can you put 2 meters on one pole, or will POCO put the meters on two seperate pole.


don't see why not.:thumbsup:


ms66cadillac said:


> If on one pole, can I run both wires from each meter in the same conduit.


hafta check but I think not. There is a rule that nothing but feeders can be 
in a conduit, but can't remember if that excludes other feeders.:huh:


ms66cadillac said:


> The one meter is going to service my shop/shed which will be near my homesite. I won't be using any welders or anything. Just basic tools that don't run on 220 or 240, whatever it is...
> An electrician is going to do this for me, but I want to make sure I am making the most economical choice, but wise choice. Is alum. wire safe to use? I hear all kinds of stories about it. I don't see myself affording copper at this time. Will aluminium get the job done?


Large AL wire is just fine. matter of fact favored do to cost/little loss oof performance at such size. I'm all over the smilies tonight so heres another:laughing:


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## ms66cadillac (Jan 11, 2011)

Saturday Cowboy said:


> typical whats that?:whistling2:
> 
> 
> come now have you talked to the POCO? do you think they're that dumb?:jester: I bet they won't count meters as much as costumers for credits? Let me know
> ...


Love the smiles...:yes:. Does the large AL wire that is being run just one strand, or will there be multiple strands? Ground, Hot, Ect? or is it just one big wire? Yes I am clueless and probably asking silly questions... If seperate strands, does the ground have to be the same gauge as the hot wire? 

So from all this I get alum. wire is the way to go. Now is it better to go up on the amps for the home just to be safe, instead of not having enough later one. So what would you suggest for a home? Its a small home 28 by 32 with a loft. The outdoor lighting in the back will be run from the shop/shed. Also you said putting a couple meters on one pole is doable? I just don't want the additional cost of another pole just to have a meter on it, since both lines from each meter will be running pretty much in the same direction and length.

Thanks for everyones help. i really appreciate it!


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## AllanJ (Nov 24, 2007)

Each meter, if more than one, needs its own cable to the building it will serve. If you need to run two sets of fat cables 300 feet from the pole to the house and workshop respectively, don't forget to decide how many amps you need on each (at least 200 amps for the house) and then figure out the cost of the cables.

I can't see any reason why two or three meters cannot be on one pole but if not, the separate poles can be five feet apart if that will save you money.

If the meters are on separate poles more convenient to the buildings, you still need the 300 or so feet of fat cables but this time a portion of the cable run will be up in the air. THe utility will install and charge you for the portions of the cable runs from the meters to the pole transformer.

The fat wires you install yourself will probably be single conductors given the weight per foot. (The conductor itself inside the insulation is stranded as opposed to being a solid bar perhaps 1/2 square inch in cross section) For transmission and distribution it is not unusual for three insulated conductors to be twisted together.


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## Saturday Cowboy (Nov 29, 2009)

ms66cadillac said:


> When you say "upstream" what does that mean in terms of the meter being upstream from underground feeders?


means your meter can't be mounted on the house thats all.



ms66cadillac said:


> Does the large AL wire that is being run just one strand, or will there be multiple strands? Ground, Hot, Ect? or is it just one big wire? Yes I am clueless and probably asking silly questions... If seperate strands, does the ground have to be the same gauge as the hot wire?


No/yes

All wire the size you will be using is what we call stranded. A wire is made up of many smaller strands in a outer insulation. You will be using 4 wires underground. Two hots, a neutral, and a ground. The neutral and the ground can be undersized according to rules. However I recommend a full size neutral.


ms66cadillac said:


> So from all this I get alum. wire is the way to go. Now is it better to go up on the amps for the home just to be safe, instead of not having enough later one.


With conduit you can always pull out wire and pull in bigger later.


ms66cadillac said:


> So what would you suggest for a home? Its a small home 28 by 32 with a loft. The outdoor lighting in the back will be run from the shop/shed.


You must do a service calculation.


ms66cadillac said:


> Also you said putting a couple meters on one pole is doable? I just don't want the additional cost of another pole just to have a meter on it, since both lines from each meter will be running pretty much in the same direction and length.


Yes two meter one pole-check with POCO.

I case your wondering how I am doing my formating with quoting, just copy the stuff in the brackets, before and after every snippet, the top bracket before and the bottom one after.


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## Speedy Petey (Feb 1, 2004)

LyonsElecSupply said:


> I think he will need to have a disconnect as it is too far away and is considered a feeder not a lateral.


I am not sure what the distance has to do with requiring a disconnect. :huh: I have never heard of that before.

Without a disconnect it is a lateral. 
With a disconcert it is a feeder. 

EITHER way 310.15(B)(6) applies. 


Saturday, your area has different rules than most of the rest of the country. In most places you can have a meter on a pole or pedestal and NO disconnect is required. The lateral goes from there to the house or other disconnect location.


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## zircon (Sep 24, 2007)

I think if you have your electrician and the power co cost it out , you will be better off if the POCO puts in another pole and gets closer to the house. They can run a small wire because they are running 8000 volts or so and they put the xformer on the closest pole. My son lives in the country in Texas and that is how I have seen it typically done there.


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## sparks1up (May 5, 2010)

You might ask your local POCO if they have a deal like the POCO here in Miami Florida. Here for around $400 they will supply the conduit for the electrician to install underground from the pole to the house and then they will pull their wire through the conduit to the house. Here they limit us to 120' though so you may still have to set a pole or two. They don't have to comply with the same rules as you would. 

btw, a disconnect at the pole that far from your house is not required, redundant and installing one at that point could then make you have to size the wiring from that point on to the calculated load and you will end up with a disconnect, a large pipe and alot of expensive copper wiring that you don't need to waste your money on.

If your local POCO does not have a deal like I described you might be better off to have a couple poles installed and run triplex overhead to your house. It would be considerably cheaper than what you are proposing! You might even ask POCO how much they charge to install a couple poles, that way it is their property and their problem should it be damaged by trees or a wind storm. Here they charge about $1000 per pole but they also wheel and deal a little sometimes so it never hurts to ask.


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## ms66cadillac (Jan 11, 2011)

zircon said:


> I think if you have your electrician and the power co cost it out , you will be better off if the POCO puts in another pole and gets closer to the house. They can run a small wire because they are running 8000 volts or so and they put the xformer on the closest pole. My son lives in the country in Texas and that is how I have seen it typically done there.


Thats what I was wondering if it would be cheaper just to run another pole, but at 5500 dollars for another 300', i wasn't sure what would be the most affordable. Guess I need to figure out how much aluminum wire cost at the size I need..

I know that going with copper is out of the picture, but from the responses on here, I am told that aluminum is the way to go. Anyone have problems with aluminum wire? 

Thanks everyone for all your help, I really do appreciate it.


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## ms66cadillac (Jan 11, 2011)

sparks1up said:


> btw, a disconnect at the pole that far from your house is not required, redundant and installing one at that point could then make you have to size the wiring from that point on to the calculated load and you will end up with a disconnect, a large pipe and alot of expensive copper wiring that you don't need to waste your money on.


Can you explain the "disconnect" to me?


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## AllanJ (Nov 24, 2007)

ms66cadillac said:


> Can you explain the "disconnect" to me?


I think sparks1up repeated himself in that sentence.

The disconnect in that case is simply a master switch out at the meter.

Whether you have a disconnect there or not, you still need cables of the same fatness to carry the load you have calculated for your house.

I am guessing that a 300 foot triplex 120/240 volt 200 amp cable in aluminum would have conductors of about 3/4 inch in diameter. Whereas if you had a pole transformer closer to your house, the 8000 volt feeder from the pole out at the property line would probably be #10 gauge, perhaps slightly fatter to sustain snow load.


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## sparks1up (May 5, 2010)

AllanJ said:


> I think sparks1up repeated himself in that sentence.
> 
> Whether you have a disconnect there or not, you still need cables of the same fatness to carry the load you have calculated for your house.


POCO does not, have to calculate their loads like electricians do. Triplex in free air for that distance and the "actual demand load" of a 150-amp service (not 150-amps) can be handled by a much smaller conductor than you would need in a conduit underground. To have POCO install poles, run their primary and install a transformer next to the house would be cost prohibitive and is not necessary.


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## frenchelectrican (Apr 12, 2006)

sparks1up said:


> POCO does not, have to calculate their loads like electricians do. Triplex in free air for that distance and the "actual demand load" of a 150-amp service (not 150-amps) can be handled by a much smaller conductor than you would need in a conduit underground. To have POCO install poles, run their primary and install a transformer next to the house would be cost prohibitive and is not necessary.


Sparks.,

You have to keep in your mind each POCO have diffrent regulations to address this so each one is not the same and I know my POCO from Wisconsin the max distance from the house to the pole is 100 meter { 330 feet } but normally 70-75meter is typcial unless it serve a service drop then it will varies a little but never over 70 meter unless they upsize the drop which they rather string out the primary little longer than extend the drop.

Allen.,

The POCO overhead primary conductor is mimum of 16mm² { #6 AWG } or larger they don't use 6.0mm² {#10 AWG } much unless a short jumper which I know in My POCO's both in WI and France do this way. and by the way majtory of the overhead lines are alum not copper unless you are right on gulf coast they may use copper conductors which I know for sure in Northen and Southern France we do use them.

Merci.
Marc


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## AllanJ (Nov 24, 2007)

sparks1up said:


> POCO does not, have to calculate their loads like electricians do..


No wonder people complain about momentary dimming of lights when a heat pump kicks on and the POCO says that the pole wiring (which is suffering voltage drop) is according to standards and "we" don't have to upgrade it.

Cables in free air can take more amperes before there is danger of overheating but voltage drop is still there. (When a wire heats up, its resistance increases and voltage drop would be even greater.)

Now yes, the chances of two homes with 200 amp services are both drawing 200 amps are very small compared to the times that one of those homes might be drawing an entire 200 amps.


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