I want to run electrical service to my barn.  Right now I have an overhead service line that runs into a transformer on a power pole 30-40 feet from my house, that feeds my house by a drop line.  My barn is 400 feet away, and I want to run underground cable to it, to provide a "208V, three phase, 215 amps" service for some equipment I'm going to run in there, plus whatever the load is for a 10 ton HVAC system, a walk in cooler, and your standard light bulbs and shit.

What should I be quoted for that's reasonable these days?  I'd rent the dingo / ditch witch and make my own trench, but everything else is beyond me and im guessing going to be in the thousands, if not tens of thousands.

Have you checked to make sure that you have 3phase available?

Trench to the pole and run a separate service with meter at the barn.  

There’s a good chance there is no 3 phase on the pole you speak of.

Edited to add open up your wallet real wide.

I'd be looking at higher voltage for the run, and stepping down when you get there.  If you use 480V, you'd have the convenience of buying cheaper industrial equipment, plus you'd have way less cost in wire. 480V to 208V transformers are cheap and common industrial surplus.

Im no electrician, but runing the service line underground to the barn, then that goes to a ground level transformer next to the barn kinda makes sense?

Copper or aluminum wire? A lot of variables.

400' with the load you're saying, VD is an issue that would need to be considered too.

Shooting from the hip, 60-70k.

Now that you mention it, I think you're right.  Two lines to the transformer isn't 3 phases.  Well... fuck.

"208V, three phase, 215 amps" that's a lot of copper.

You need to contact your utility company and check on your options. 400’ of secondary is a long way.

Pics of overhead service ?

So here is the deal: Electrons that flow through a conductor in an AC system alternate back & forth at a rate that is based on the frequency. This is measured in amperes, or amps. An amp is equal to 6.28x10 to the 18th electrons flowing past a given point per second. Think about that. That is a metric fuckton of little negatively charged jobbers being transferred from valence ring to valence ring of the atoms within the conductor.

As a result, work is done based upon the design of the load but heat is also created within the conductor. This is due to friction. As an example, do the Mr Miaggi wax on wax off hand rub thing. The more vigorous you wax it off the hotter your hands get. So from this we can see a limitation of any conductor is heat. The more electrons flowing the larger the conductor needs to be. A 12 gauge copper conductor can, per the NEC code book, can have no more than 25 (I think) amps flow through it. However, it is only allowed to be protected by a maximum 20A OCPD (overcurrent protective device) but that is a different discussion.

A 500kcmil (kilo-or thousand- circular mil) conductor can have up to 380A flow through it per the NEC. This is all based on the 75degree Celsius scale in table 310.15(B)(16). This table was formerly 310.16 up through the 2008 NEC & was changed in the 2011 edition. Reason being is that tables in the NEC are numbered based on the section that refers you to said table. There never was a Section 310.16. But back to the amperage thing...

So, this 75degree scale is what I personally always use, as opposed to the 90degree scale, because damn near all lugs on a breaker are rated for 60/75degrees but not 90. You see, any circuit rating is only as strong as its weakest link. If a conductor is sized based on the 90 scale but the lug isn't, than the lug will potentially get hotter than it is rated for and fail. Now some of you are saying that there are lugs rated for 90degrees and you would be correct but many circuit breakers are not made with these lugs. Always check the temp rating of your termination lugs. Look for a marking like 'AL9CU' or 'CU9AL. The letters mean that it is rated for both copper & aluminum while the 9 means that it is 90degree rated. If the '9' was a '7' than it is only rated for 75degrees.

Okay, where was I...oh yeah ---> amperage flows from the source, through the load, & than back to the source. Amperage, or current, should NOT flow within the grounding system. All of the green wires in the system are there for safety. There are different names for different parts of a grounding system based on where it is within the system. The part that makes the physical connection to the earth is the grounding electrode. 250.52 allows for the following types of electrodes: rod, pipe, plate, ring, concrete encased (commonly called a ufer, named after some guy named Ufer because he founded the use of this type of electrode), steel structure of a building, underground metal water pipe, and probably a couple more that I can't remember right now. There are restrictions to material type, install method/rules and such but I ain't going there right now.

The conductor that connects this electrode to your panel/switchgear is the grounding electrode conductor. This is sized based on the equivalent size of the service entrance conductors and isn't required to be larger than 3/0 ( that's 3-ought or 000). You see, on the American Wire Gauge scale the larger numbers are smaller wires and as the wire gets bigger it's AWG number gets smaller. Example being numbers going as such:12, 10, 8, 6, 4, 3, 2, 1, 0(1/0 or 1-ought), 2/0, 3/0, and finally 4/0. From here, the size is simply the circular mills of the conductor starting with a 250kcmil, 300, 350, 400, 500, 600, 750 and so on up to 2000. 750 is a big bitch, I couldn't imagine pulling 2000's!!! Who of you still call a 500 like this---> 500MCM? This is old terminology that means the same thing as kcmil. The first M is the Roman numeral for 1,000 just like k is the metric prefix. The CM than means circular mils.

What is this unit of circular mils that I speak of? It is an area measurement specific to conductor sizing. A mil is a linear measurement equal to one/thousandth of an inch. A circular mil is mils times mils. This formula is not like the area of a circle measurement which is (pi)(r)(squared). Why does the area of s conductor differ from the area of a circle you ask? I ain't sure except to probably get to a much more specific number for it value. A 12awg is 6530 mils, a 10awg is 10,380 mils & I don't remember any others right now. We can talk raceway fill (based on area) and box fill (based on volume) but that's a whole different discussion so back to grounding.

The conductor that connects the grounding conductor to the grounded conductor at the service is the main bonding jumper (system bonding jumper at a seperately derived system such as a transformer). This can be a wire, bus bar, or screw depending. I'm sure you are wondering what this 'grounded' conductor is that I spoke of? This is the system conductor that is intentionally grounded & is commonly called the neutral. It isn't always a neutral and could be a corner of a corner grounded delta but... This neutral is identified by white or gray insulation or black insulation with white or gray tale at its termination points. The neutral IS a normally current-carrying conductor. In your house on a 120v ckt the black, ungrounded 'hot' wire is where the current starts to flow through the circuit conductor toward the load. The neutral is the return path for this current back to the panel to the neutral bus, through the grounded service entrance conductor and finally back to the source or transformer winding(s).

The grounding conductor is the conductor that is continuously performing the grounding, or making the connection to, the metal non-current carrying parts n pieces of all the things. There should NOT be any current flowing on this conductor. This is the green, or bare conductor. What is the purpose of this grounding conductor? It's three fold actually: to put all non-current carrying metal parts at the same potential as the earth (remember the grounding electrode, grounding electrode conductor and main bonding jumper), to perform bonding duties & to be able to safely carry ground fault current to help facilitate the operation of the OCPD. Ground faults are typically high current faults that can be 1,000's of times higher than normal current values. During a ground-fault LARGE amounts of current flow from the source, through the circuit breaker, through the grounding system and back to the source. This is why the secondary windings of a transformer are grounded & why the main bonding jumper is what it is. The main bonding jumper provides a path for this fault current to flow back to the transformer. The circuit breaker says OH SHIT THIS IS WAY TO MUCH CURRENT!!!!! I NEED TO OPEN MYSELF UP!!!! Hopefully it does, as opposed to blowing the fuck up. You see, any OCPD has a rating called its AIC (amps interrupting current). This is the amount that an OCPD can safely have flow through it before it blows the fuck up.

Gear has an SCCR rating (shirt-circuit current rating). Kinda the same but more specific to the bussing in the gear. The higher the rating the more, stronger the bracing for the bussing. I mentioned that heat is created when current flow but one more thing happens. A magnetic field is created when current flows. Copper is non-ferrous (can't be permanently magnetized) but can become an electro magnet. Basically to magnetize a material you need to align many many of the atoms within it. During current flow some of the atoms, specifically electrons, all flow the same direction and work together so that their individual magnetic fields add to each other. The higher the current, the stronger the magnetic field. High faults can easily cause wires to slap around in conduits or for bus bars to be physically attracted to each other (bent like a motherfucker) until they possibly touch each other and blow the fuck up!!! KA-FUCKING BOOM!!!!

I can get deeper into this, explain how transformers and motors work, what voltage, resistance & power are, how to bend conduit in every way, and a bunch of other shit but I need to stop typing so I can get back to chugging my Keystone Lights.

TL:DR OP doesn't understand electricity...

Yep.  Phase and a ground.   Not three phase.   Your are SOL.

For service, yes.  But you can get solid state phase adapters that are pretty efficient. Single/split phase in one side and three phase out the other.

I actually read all of this, and realised, you electricians are worth every cent.

If there’s only one pole mounted transformer then you will need to talk to your utility about three phase.  Is it single phase or three phase primary line that is feeding to your place?

  OP.....

My power company has a cost calculator on their website.  It put me at $6k-$8k estimate.

  I had  200ft run from the pole, into a trench (I paid my excavator guy to dig the trench)

Power company installed conduit, new transformer on pole, pulled wire, connected to temp power pole, installed new hand hole for future connections.

It wound up costing me $6K after everything was done.....but they sent me a $1K refund check which I was happy to accept.

This was June of 2020.

Not exactly the same but I spent 90k on a 50kva to 350 upgrade for 208v last year. I think the spool for the wire in the trench was 20k by itself.

What part of VA are you in, I am licensed in VA.

My honest answer would be to set a few poles, have them take high voltage to a new pole outside the barn and set a new 3 phase service. It will be a lot easier and really the only way you will get 3 phase there. You could try to get them to run it under ground, but the smallest transformers for 3 phase that are ground mount are a LOT bigger than you need. The fees from the power company will be based on how much power you use, the less power you use the more they will charge you up front. With any luck you have dominion power they are one of the cheapest to do this type of work, and honestly pretty damn flexible. ( also they tend to supply transformer pads for ground mount that cost 2500 if bought from pepco )

You can start a new service app with your power supplier and list your loads and required voltage. This will start the process with them and get a designer started on it. But be warned its not a fast process.

Yep, go drive down your road, you will probably see where your single phase neighbor hood service comes off the 3 phase lines.  That is where you would need to run 3 phase from, mine was 2 roads away on the state route, AEP only quoted me $210k to run high voltage 3 phase back to my property.

Needless to say that won't be happening, I got another quote for just a 480v single phase line dropped to my shop. That would just be a separate pole mounted tranny and a short run, $28k. With 480v I can run (inexpensive to me) VFDs to convert single phase into 3 phase for running any industrial machine.  This could be done with 208/230v

I see a phase converter in your future.

Take a picture of the utility pole feeding your transformer. If you have two or three primary phases carried on it, then it is possible to get 3 phase service. There are lots of two phase runs in my area, mostly to service farms. It's cheaper for the power company to run and will still provide an open 3 phase service.

There is plenty of theory & science behind it, no doubt...

Probably 20k

Id agree with that ballpark.  I'm having a ~300' 600 amp 480V delta feed ran overheard in conduit right now and im
roughly double that price.  Pulling from an existing transformer.



This.  Go 480V, stepping down is easy.

Two phase service?

Yep. It's really used for three phase, fed by two phases. Very common. Two transformers usually an open, high leg delta configuration.



ETA, notice there is no winding or connection between A and B phase, but there is a potential difference there. These systems can provide about 57% of the power that a full 3 phase closed bank can. For residential and light commercial they are just fine.

Here’s an example for you.

I have 3 phase at the front of my property. Have existing poles to a transformer 400 ft back to a transformer by the house. Shop is another 100 ft from that.  

I was quoted a starting number of $50k to run the 3 phase to where the existing transformer is.  Apparently 3 phase poles have to be taller. They would have to remove and replace all the poles.

I’ve decided to run a separate single phase 400 amp service to the shop and buy a phase converter.

I'm at 25kish for the service, and not knowing the size of the building or anything can't really shoot a number off the hip. I didn't do a VD calc so assuming 350kcmil quad aluminum in 4" PVC with steel sweeps.

get four phase.  WAAAY bettter  (at least a quarter better)

Exactly this. See if the power company can revenue justify this. But they are going to want a bunch of info from you.

hell, at this point, he may as well ask for 5 phase!

That's not two phase power. That's open delta three phase. Two phase is pretty limited to the Philly area. I guess Hartford Connecticut too from wiki. Regardless in two phase the two phases are only 90 degrees apart not 120 like an open three phase.

https://en.m.wikipedia.org/wiki/Two-phase_electric_power?

its fed by two phases but provides three phase power. I thought my picture and explanation was clear on that. Maybe not?

Here it is from the GE Distribution manual.  

Attached File

Yep. Just did one of these for a machinists that bought a bunch of 3 phase equipment for his house shop and had no 3 phase at the poCo. I want to say it cost his him about 20k just for the machine but it’s doable if 3 phase is a must.

This is the Scott connection from a 3 phase service.  This is the old 2 phase service that is 90 degrees out that is referenced above.  

Attached File

String Spaghetti overhead. You can get away with murder in free air, but probably won't get 3 phase without a converter or $$$$$$$.

Yep. Thats exactly what rhe transformer configurations look like for the open systems around here. We have wye primary that is 12.5kv phase to phase and 7,200 phase to ground.

ETA, here is what one looks like on the pole except with with two cans, one center tapped to ground.. It's down the road from me and used to feed a barn that is no longer there. Notice it has only two of the primary phases availale and the grounded coonductor.........

Feed by two phases of a three phase system is still called single phase. Two phase is a specific term for a specific system and what you are describing is not it.

My coop dropped a pole 20 feet from my barn, hoisted a transformer, tied into the overhead service lines and told me to call them back when I had the meter box and panel installed and inspected.

Cost me nothing from them.

Underground is nice, but you might be damn close to breaking even by building a new barn closer to the power!

Damn dude...you typed a term paper.

Uh, no. It is an open 3 phase system. The two phases are 120 degrees apart and all the math for the volitages and etc works out on the square root of three.

ETA, you can derive single phase out of it (like any other three phase system), but it functions as a three phase system as a whole.

Its like deja vu all over again

Terminology is everything here.

There is an actual 2-phase system design that was/is in use nowadays. A couple previous comments made mention that it is still in use in PA somewhere. Shoot, there is also some sort of a 6-phase system I've seen on paper, don't recall its specifics though (voltage, connections, winding config, phase angle, etc...).

An open-delta is a 3-phase secondary that doesn't have that third winding to connect A-C, as you stated earlier. Its available power is lower than a closed delta of equal winding size/ratings, also as you stated earlier, due to the lack of the third winding.

Terminology gets a bit loose here: A 3-phase system has (3) ungrounded conductors (wye, 4-wire deltas, ungrounded 3-wire delta). If (2) of those (3) phases of said 3-phase system are utilized to supply a load that requires only two hots, that is considered a single-phase load and is supplied by single-phase.
  To further elaborate: If its a 3-phase 480v system, then those (2) of (3) ungrounded conductors would be called single-phase 480v, even though they are derived from a 3-phase system.
  Suppose you could call is 2-pole 480v as it'll be protected by a 2-pole breaker, but nobody does.

The term '2-phase' is bad, should feel bad & isn't used in most-any theory discussions unless it is in regards to that rare 2-phase system mentioned earlier. Ain't no 2-way toggle switch either, but thats not pertinent right now.

That's how its spoken everywhere I've traveled and by everyone I've spoken to.

I've used the word 'phase' to describe the system itself as well as a circuit and load supplied from it...



...clear as mud, ain't it

Yeah, there is a lot of terminology afloat. The imaginary phase of the open system still has a potential difference across it and that's how they take advantage of it and end up with a real 3 wire system (usually with grounded neutral) at the user end.

A lot of pepole mistakingly think that a single/split phase system (such as your typical, average residential service in North America) is two phases. While it is true that the 2 legs are 180 degrees apart with respect to neutral, thay are in fact the same phase, just opposite polarity.

Yeah I know of it.  At least in theory.  I think they're separated by 90 degrees instead of 120.  I've just never seen it.  Never even talked to anyone who has seen it and mentioned it.  I'm not a master sparky though.

I was going to call shenanigans, since most people mean single/split when they say two phase, but these threads tend to draw people who know what they're talking about.

Most people don’t advertise online like this when they plan to construct a grow house

What is the name of that book you have?

Here you go.   It is a great reference.

Attached File

How are you making 3 phase power?

is your barn a musty metal 2 car garage?

Attached File