Main electric service line too long?

bebster · Oct 20, 2005

To those who replied to my recent Cat5e pulling post -- thanks! I am also planning to run by main electric service line from the pole to the house. Total wire run is 400' from the pole to the main panel. My electrician is suggesting using "0000" gauge wire and burying it in 2 1/2" pvc conduit. Yesterday the electric company suggested that is too marginal and the voltage drop will be too high, and I should run a primary up close to the house and put a transformer pad there. Any suggestions? I was just about to begin digging the trench with my tractor next weekend!

RobS · Oct 20, 2005

I'd go with the electric company recommendation. Usually, that's their nickle anyway other than an upcharge for underground versus above ground wiring. Our house is about 500 feet from the utility lines and we have our own transformer box on the ground. Nice, bright lights all the time /forums/images/graemlins/cool.gif Neighbors are a bit closer and started with a pole hung transformer at the street. Had all sorts of problems with dimming lights and motor start ups. They got the electric co. to give them a transformer at the house and all is well /forums/images/graemlins/smile.gif

bebster · Oct 20, 2005

Here the electric company will give me a "2 pole" credit toward the transformer and 4' underground wiring. I suspect this isn't that much and the tab will be high. In addition to the cost, this will mean a 2 month delay since I'm sure they'll be slow on the design and construction etc.

I was able to find this voltage drop calculator.
Voltage Drop - Wire Size calculator

If I use copper 0000 gauge wire 400' long and drew the full 200 amps on the main panel, I'd get a 3.9% voltage drop. But I'm not sure if that's too much or not that bad.

LarryRB · Oct 20, 2005

I've done a fair amount of trenching for underground electric and have one question,, how are you getting away with 2 1/2" pipe when out in this side of Mass and CT for that matter, the electric companies require 4" schedule 40 at a minimum for anything over 200 feet... Also, the sweep to the poles now has to be in steel and no more PVC (just the 45 sweep)

Farwell · Oct 20, 2005

I would go with the power company's suggestion. Better to suffer a small inconvenience now over a large one later. Don't know if you have ever worked with 0000 cable, it is like trying to run three 3/4 inch steel water pipes into conduit. It can fit into 2-1/2 conduit but it will be a lot of work, require the right equipment to pull and someone that really knows what they are doing. I think three inch conduit minimum and probably better off with 4 inch if you decide to run your own wire.
Not sure of how the power company charges for installation in MA but in a lot of areas they charge for anything after the primary drop, if that is true in your case, you will save a big bunch of bucks. Check the price for 3ea 400 foot lengths of 0000 copper wire plus conduit and the hook up cost.
IMHP
Farwell

Tim_in_IA · Oct 20, 2005

definitely go with the power companies recommendation. You want that transformer as close to the house as you can stand it. I'm running 0000 at about 140' and this works well for 200amp service.

CTyler · Oct 20, 2005

</font><font color="blue" class="small">( I should run a primary up close to the house and put a transformer pad there. )</font>

Yes, that is what you want.

cmuncy · Oct 20, 2005

I have 1400' of primary running to my transformer pad 100' away from my house and 100' away from my shop. Best investment I ever made. I had to pay $4.00 per foot after the first 1000' of primary and that was it. All underground btw. That and nothing but 12 gauge wire and hire in my house and I don't EVER have a dimming problem. /forums/images/graemlins/cool.gif

bebster · Oct 20, 2005

My electrician is going to thread 10' lengths of pvc conduit 2 1/2" in diameter onto the 4-ought wire, and then glue them together. Kind of like making a beaded necklace on the ground, and then placing it into the trench that's 2' deep. He's an experienced guy so I want to give him the benefit of the doubt.

midlf · Oct 21, 2005

two thoughts:

Electric co. will have to spend more of their $ to do what they recommend. You will have a shorter run, thus less $. Electrician wants you to make a long run thus more $ to them. Think about it.

Second point. All conduit is to be installed as a complete system per NEC or NESC and then the wire pulled into it. If conduit is being threaded onto the wire something is wrong with this installation. Again, think about it.