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Discussion Starter · #1 · (Edited)
Right now at my pole barn I have a 12 gauge wire running from my house to my pole barn. It says 600 volts on the wire. It is 300 ft from the house.
The wire has 3 strands and runs underground.
My house has 200 amp service ........fwiw

So I built a pole barn addition. I need to upgrade electric. The old barn has a 30 amp box.
It's old it's orignal, like mid 70's. At least the pole barn. I assume service is the same.
So I bought a 100 amp box. My original plan was to add a 2nd meter as the power company has a transformer nearby. However, this will cost $30 / month in perpetuity.

2 other choices here:
1) Hook new 100 amp box into the existing wire/ power source.....and what do I get for power?

2) Trench it and run the lines necessary from house to get sufficient power. What would that power line look like?
p.s.--- not trying to steal work from anyone. Just making plans, and satisfying my curiosity. I will not do this work myself.
 

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Although I am not a sparky, running #12 300ft you don't have much power at your barn now,

#1 a new 100 amp box is not going to give you any more power, still should only be using a 20 amp breaker any thing else and you will have problems.

#2 Would be the best way to go if you don't want the $30 a month bill. What the power will look like depends on what all you are going to run in the barn . Pretty much need a electrician to do the load calculation and voltage drop that far so things end up right.

I would think that some electricians will have some to add to this.
 

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Well here I am..lol. First I need to know what the total load for the barn will be. Then I can calculate the voltage drop and let you know the size wire you need to run. It also need to be a 4- wire feeder, if you want to have 240 volts at the barn.
 

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Discussion Starter · #5 ·
I've been told to figure in a 240 circuit.
Load? You mean outlets and uses?
If so, there's no mechanical s. No heat.
Although there is a well pump in the floor I'd like to get going again. (I've owned the place 3 yrs. Well was in already)

Just lights and out lets. I was figuring 15 / 20 amp outlets.
the new addition will have 2 rows of 5 lights each. The old barn has three overhead

I'll have some fluorescent here and there, like over the work bench, brake area.
At some point there'll be some Marshall & Fender amps...........

So when you figure the load, is that based on everything being on at once?
( I Know nothing!)
 

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Need to figure up the worse case scenario. That is what you may possibly have on at the same time. Ill need the amp or wattage load for each of those items.
 

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You could do a load calc but if you have gotten away with 12ga for the few items you are running then i would say run 100amp "2ga" 4wire from your home to the barn and feed a 100amp 20slot panel. You are going to have some voltage drop so either increasing wire size or switch to copper would help. Personally i would just increase the size wire for cost.
 

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I would go ahead and install that 100A panel and feed it with a 2 pole 60A breaker.

Run PVC conduit from house to barn and pull in: 3 #4 CU conductors and 1 #8 CU ground

That should do you for your voltage drop. You are allowed 3% for load, but make sure you have the right voltage at the panel before finding out you lost 5%, which is allowable.
 

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That should do you for your voltage drop. You are allowed 3% for load, but make sure you have the right voltage at the panel before finding out you lost 5%, which is allowable.
There is NO such thing as "allowable" voltage drop.
Voltage drop consideration is NOT a code requirement, it is a "fpn" suggestion in the code book.
 

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Need to figure up the worse case scenario. That is what you may possibly have on at the same time. Ill need the amp or wattage load for each of those items.
How can he give you specific amperages/wattages when he does not know what'll be used?

In cases like this I normally just wing it. After all these years it's not hard to figure what size feeder to run to certain residential outbuildings based in the building's intended use.
 

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There is NO such thing as "allowable" voltage drop.
Voltage drop consideration is NOT a code requirement, it is a "fpn" suggestion in the code book.
Yes, you are correct and thanks for correcting me. The "allowable" voltage drop is just a suggestion and voltage drop is not a fire hazard safety issue, it is a performance issue. Which I did not quote anything from the code book.

I will re-phrase my "Suggestion"

You are suggested to not loose more than 3% voltage from a load and total suggested voltage drop should not exceed 5% from service to load overall.
 
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