Running power 4000 feet

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mbrooke said:
Thank you! Those numbers are a life saver! :happyyes::)

Then I will go with 3 phase.

Im however tempted to pick a 208 delta 600Y transformer just so I can have a mid point ground.


If I did choose 1000 volts, I would need cable other then typical THHN/THWN?
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Why?
You want a single phase not three phase supply.

UK cable costs are crazy, it’s cheaper for me to buy 25mm² 4c SWA than 50mm² 2c. 4c is “off the shelf” 2c would be to order. I would double up on the cores in a smaller cable and save money. The one proviso would be, they are correctly identified at the terminations.
 
Is there any chance of the user accepting poles?

You might also be able to find that you can get a second service a lot closer and a lot cheaper.

Being as it is outside maybe you could tap off the service conductors downstream of the meter to feed this building.
 
Tony S said:
IEC agree with <1000V AC <1500V DC as LV. They’d better do, they set the values.

I can’t say about your cable ratings without looking them up. Our BS2764 SWA is rated 600/1000V (600V to earth, 1000V Ph to Ph). I’ve tested them to many times that.

As I said earlier the cable jointing is going to have to be done by a skilled person. As always joints are the weak point. (My knees included.)
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Exaplain, don't typical terminations hold up?


Stress relief doesn’t come in to play with <1000V just common sense. Not putting sharp bends in the joint or termination conductors.
For MV it depends on the cable construction, screened need stress relief, unscreened extra insulation in the cable crutch, (this is sounding perverse now!)
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Here in the US I believe all cable in the MV range is screened minus temporary jumper cable but Big John will have to correct me on this. How are you cables? Can you get 5kv un-screened? 11kv un-screened?



I can work on up to 33KV cables, that is where stress relief really is needed. Now that I’m retired there’s no chance. Horrible muddy holes, rain, snow, etc. The jointers mate bailing the hole out with the pan I was planning to cook our breakfast in. To hell with that game!
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Oh yahhh! :eek: 12 kv is not to bad (compared to the latter), but when you get into the 25 and 35kv range there is no room for error. Corona is not to be taken lightly here.



Only once did I get a cable jointing job I really enjoyed. Four 11KV through joints at the side of a pasture, glorious summer days, beautiful Derbyshire dales scenery. The local farmer was bringing us eggs, home cured bacon, home made sausage and black pudding along with a Derbyshire specialty, oat cakes.
Strange how that job ran on for days longer than it should have done.
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:lol: I dont blame you, sounds like a job I would do anything for. Where there is food you will find me! :thumbsup:
 
Tony S said:
Why?
You want a single phase not three phase supply.

UK cable costs are crazy, it’s cheaper for me to buy 25mm² 4c SWA than 50mm² 2c. 4c is “off the shelf” 2c would be to order. I would double up on the cores in a smaller cable and save money. The one proviso would be, they are correctly identified at the terminations.
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I am getting the idea a single phase unit would cost more then a 3 phase, but then again anything custom is eye water lol.
 
petersonra said:
Is there any chance of the user accepting poles?

You might also be able to find that you can get a second service a lot closer and a lot cheaper.

Being as it is outside maybe you could tap off the service conductors downstream of the meter to feed this building.
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The cost of extending the service is massive, either a 120/208 conduit will have to be run 4000 plus feet to the existing pad mount or the POCO will charge to run an underground URD cable and a new pad on private property.


Of course there is a customer owner overhead system with pole pigs. I will look into that, but to be honest I have no idea how to wire overhead lines to the NEC. NESC yes, but no clue about the NEC.
 
Poles are probably cheaper then UG. You might want to find out who the POCO uses and chat with them.

My guess is that any entity with this kind of money can afford whatever they end up with. I find it odd though that there is not a closer set of utility lines than 4000 feet away. Another service might be the simplest answer.
 
petersonra said:
Poles are probably cheaper then UG. You might want to find out who the POCO uses and chat with them.

My guess is that any entity with this kind of money can afford whatever they end up with. I find it odd though that there is not a closer set of utility lines than 4000 feet away. Another service might be the simplest answer.
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Its a rural private property, hence the situation.
 
mbrooke said:
The cost of extending the service is massive, either a 120/208 conduit will have to be run 4000 plus feet to the existing pad mount or the POCO will charge to run an underground URD cable and a new pad on private property.


Of course there is a customer owner overhead system with pole pigs. I will look into that, but to be honest I have no idea how to wire overhead lines to the NEC. NESC yes, but no clue about the NEC.
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Have you asked the utility what it would cost to run primary to new transformer? The last one we did that was 2900' feet away, we had the utility extend their overhead lines 1600' closer and then set a 480 3 phase service. We then ran an underground feeder from the service for the last 1300' to a 480-240/120 trans to step it down.
 
Cow said:
Have you asked the utility what it would cost to run primary to new transformer? The last one we did that was 2900' feet away, we had the utility extend their overhead lines 1600' closer and then set a 480 3 phase service. We then ran an underground feeder from the service for the last 1300' to a 480-240/120 trans to step it down.
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How much did they ask for? Were they willing.
 
mbrooke said:
That would make sense in way since anything over 600 volts goes into the medium voltage range. But, I saw somewhere in the NEC where 600 volts was changed to 1000 volts recently, what does this change?

Edit: I found this, hence my confusion:


http://www.ieci.org/newsroom-and-insights/600-volts-to-1000-volts
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I have cogitated on using PV wire for a long run like this. That would get you up to 2kv. It's kinda seems like a loophole for getting into MV territory. With the right arrangement, i think you could get away with no other MV gear other than the transformers. I doubt anyone makes al PV wire, but at 2kv your wire and conduit would be nice and small.
 
mbrooke said:
That would make sense in way since anything over 600 volts goes into the medium voltage range. But, I saw somewhere in the NEC where 600 volts was changed to 1000 volts recently, what does this change?

Edit: I found this, hence my confusion:


http://www.ieci.org/newsroom-and-insights/600-volts-to-1000-volts
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Didn't check into your link, but NEC did replace 600V with 1000V in several sections - but I don't think they have done a complete change of all places that once said 600V to 1000V - yet, but may be coming eventually. I think it has some to do with aligning with other standards that do essentially call anything below 1000V low voltage and above is medium or high voltage.

If POCO runs single phase medium voltage they will run a single coaxial type cable. If you run it (per NEC) you need separate grounded and equipment grounding conductors. Maybe see if anything POCO will let you install raceway and let them pull their cable through it and connect a new service. Some POCO around here require that anyway - they assume maintenance of it down the road, they just don't want to trench the raceway in. Standard for single phase MV cable from them is 2 inch conduit - your choice of PVC, or HDPE - which is easily plowed in if there are no obstacles to cross or rocky conditions.

petersonra said:
4000 feet is the better part of a mile. Very few places where there is not electric service run along every road in rural areas and few places that are more than 4000 feet from a road.
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You must not come out to God's country very much. What you said is fairly true around where I live, but you don't have to go too much further west to find places that are several miles away from the nearest electric utility. Even those places I mention are easy to get power to compared to many places in the Rocky Mountain range.
 
Tony S said:
Being metric I had to work the length to understandable figures for myself

4000Ft = 1.2Km.

I definitely wouldn’t want anything to do with that drum of cable!
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I thought all Brits were conversant with Imperial measurements. After all, you invented them.
 
Cable stress relief is a whole new subject and needs a new thread.

At 1000V cable joints will be sealed. The transformer terminations are likely to be in free air and moisture then causes problems. Tracking distances are tabulated for various types of insulation medium, temperature and relative humidity.
 
kwired said:
You must not come out to God's country very much. What you said is fairly true around where I live, but you don't have to go too much further west to find places that are several miles away from the nearest electric utility. Even those places I mention are easy to get power to compared to many places in the Rocky Mountain range.
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True. In some cases private home owner's find it more economical to go with solar and a back up generator instead of paying the amount the utility charges to put them on the grid.

Interestingly, the heart of the Rockies was where AC power got its start in the hard rock mines. The fact that the terrain was tough didn't matter, it was cheaper and safer to build an AC power plant than it was to haul coal to make steam. Check out this link.....http://www.coloradocountrylife.coop/this-is-what-grit-looks-like-tough-men-in-hard-places/
 
If the decision is made to go step-up:run at 600V:step-down, then would it be reasonable to use a boost transformer arrangement rather than an isolation transformer?

If you use single phase 208:120 transformers (standard, off the shelf units), and connect them in a wye boost arrangement, then you would get 568V, close enough to 575V.

-Jon
 
ActionDave said:
Can you do that? Use a transformer above its listed applied voltage? Legally??
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Forget legally. If you apply that high an overvoltage you would saturate the core and blow the OCPD. If it did not it would burn out instead.
But in this case the suggestion was to wire it/them in a boost arrangement.
However, for three phase it would take three separate transformers if you could not separate the windings at the wye point.
And the voltage to ground would exceed the design level.
 
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