# Wire size?



## dcc (Mar 19, 2007)

I use Voltage Drop Calculator.

At 400' using copper it suggests 600 kcmil.


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## brian john (Mar 11, 2007)

Thats the service size what is the actual calulated load?

I have monitored houses for kwh usage and seldom do we see anywhere near the calulated load, unless there is electric heat.


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## RCG (Mar 11, 2007)

Thanks for the reply guys. He has a house with an exsiting service up at the front of his yard. He built another house in the back of his property. That house is 1200 sf downstairs but, he will be finishing in the attick later on (900 sf). That is what the 200 amp service is about. I think the only thing he has is an electric range. So, probably not much of a load on the service. Also, I gave you false info. It is only about 300 foot back.
Another question is, if the meter is going to stay at the front of the property, do i need a disconnect with it? And then run from the disconnect (300') to the panel at the house in the back?


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## faber307 (Jan 22, 2007)

why two houses with 1 meter?:blink:


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## brian john (Mar 11, 2007)

One meter, one service charge. SAVINGS. meter at house might make the utility pick up the cable charge. SAVINGS.

Is the meter location the service location, I would guess yes and then the answer is yes.


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## RCG (Mar 11, 2007)

No no.. he is building an additional house in the back. He would like to keep both meters at the front of the property. Is that even legal?


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## dcc (Mar 19, 2007)

So he's going to have a second service with it's own meter and he wants to keep the meter in the front of the property with the other...no problem. As I recall you will need to have a means of disconnect at that point.

As for the size of the conductor, the size of the panel being installed will determine the size of the conductor, the voltage drop is the only other consideration.


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## RCG (Mar 11, 2007)

Thanks for your reply dcc. Yes, he does want the meters at the front of the property. I would assume that there should be a disconnect there of some sort. I Think that I will run 4/o inside of 4" schedule 40. I am not sure if I should use schedule 80 instead? Any ideas.... code wise? oh yea, I am in California...


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## dcc (Mar 19, 2007)

Your main breaker should be in that panel and that would be the disconnect.

At three hundred feet with 4/0 you are going to have a voltage drop of 3.5%, you will need to go to 350 kcmil (mcm).

What part of Ca. are you in?


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## RCG (Mar 11, 2007)

Thanks dcc. I am in the bay area (Contra Costa County). This kinda puzzles me. I am trying to convince the customer to put the meter on the back house. Its kinda dumb if he dont...


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## dcc (Mar 19, 2007)

Not knowing the circumstances I can only speculate, but if the property can be split and the owner is considering selling the second house and property obviously the service should be brought to the new house. If the property can't be split then there are determining factors like the location of the utility pole where the service is coming from and the distance to the house. Another consideration is the location in regards to the line of travel from the pole to the new house. If the distance is great enough PG&E may require a second utility pole for an overhead service, this could become expensive compared to running underground from the existing house. If the utility pole is on the owners property then another option would be to run the service underground form the pole to the new house. I'm guessing that the property isn't in a newer subdivision where the utilities are underground.


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## HCECalaska (Mar 21, 2007)

200 amps is the service size but not the load. actual load if the service is sized properly wont be above about 160amps generaly any load drop less than 5% is acceptable i normally design around 4% max. without looking at a code book or using my calculator i would imagine a 4/0 is sufficent for this load


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## jproffer (Mar 24, 2007)

Don't mean to butt in somewhere I may, or may not belong. But I changed a service here and the POCO (ameren) doesn't care if you're putting 2-20A breakers in a 200A panel. You have to size your side of the meter to the panel capacity, not the load. Their side is on them, and it's their specs, so they can do whatever they want. When starting this that's pretty much what they said. "Our side is going to be small (we went from 100A to 200A), but we're not going to change it unless it becomes a problem...but you don't have to worry about that, that's our problem and our expense if it's ever necessary"


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## RCG (Mar 11, 2007)

Thank y'all very much for the replys. Come to find out, the property cant be divided. So, I decided to run two 350kmcl and one 250kmcl underground about 380 feet. I am going from a diconnected meterbase to the back house sub-panel. It as all ran in sched 40 with a 2'X3' pull box at 200 feet.
And to agree with jproffer, I too have always ran wire size according to panel size. That load deal is not were I am from. haha..


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## Dembones (Mar 24, 2007)

HCECalaska said:


> 200 amps is the service size but not the load. actual load if the service is sized properly wont be above about 160amps generaly any load drop less than 5% is acceptable i normally design around 4% max. without looking at a code book or using my calculator i would imagine a 4/0 is sufficent for this load


3% for feeders, 5% from the point of service to the farthest outlet served.


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## brian john (Mar 11, 2007)

> 3% for feeders, 5% from the point of service to the farthest outlet served


Not code only a FPN.


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## Speedy Petey (Jan 10, 2007)

Exactly. Accounting for voltage drop is a suggestion, NOT a requirement.

dcc, what parameters are you using? You're not using 200 amps are you? 
What about service sizing? You went from 4/0 to 350. What about 250's? 

The voltage drop calculators do not take 310.15(B)(6) into account. 
You cannot use regular VD calculators for services. If you did most services would be undersized regardless of length.

Using a regular VD calc with the following:
2/0cu
150'
240v
160 amps

The drop is 4.64%, yet we all know this is an absolutely typical installation.


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## Dembones (Mar 24, 2007)

brian john said:


> [quot]3% for feeders, 5% from the point of service to the farthest outlet served


Not code only a FPN.[/quote]
Thanks for the correction, remember reading it but I left the good book in the job trailer:whistling2:


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