new underground service connection

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  #1  
Old 05-14-06, 01:54 PM
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new underground service connection

I am putting in an underground service cable to my new house.
From the meter pedestal to the point of entry to the house is approximately 225 feet. I am told that 4/0 aluminum will be ok for this, but I am concerned about the drop over that distance.
Immediately below the service meter I have to install a 200 amp breaker then run the 225 feet of wire to the house.
1.) Will the voltage drop be too much?
2.) If so, then what size should I use and aluminum? or copper?.

Obviously dont want to spend more than I have to spend, or work harder than I have to work, but I do want to have it correct in the end.
Thanks for the advice.
 
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  #2  
Old 05-14-06, 03:20 PM
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Underground Service

Steve
I can not answer your question. You need to caculate the voltage drop based on the load in the house as given in NEC 220. If this is not something you do daily, you need to get someone to do the caculations for you.
 

Last edited by wareagle; 05-14-06 at 04:51 PM.
  #3  
Old 05-14-06, 05:19 PM
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Originally Posted by wareagle
Steve
I can not answer your question. You need to caculate the voltage drop based on the load in the house as given in NEC 220. If this is not something you do daily, you need to get someone to do the caculations for you.
That's OK WarEagle, I cant answer it either. I hope that someone out there can answer it, and enlighten us both!
Thanks.
 
  #4  
Old 05-14-06, 09:18 PM
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Steve
The reason it can not be answered is because we do not know
what the house load will be. You use Section 220 and the installed
electrical load to caculate the voltage drop.
 

Last edited by wareagle; 05-15-06 at 08:50 AM.
  #5  
Old 05-16-06, 12:20 PM
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Is the extra cost worth it?

Originally Posted by stev703
That's OK WarEagle, I cant answer it either. I hope that someone out there can answer it, and enlighten us both!
Thanks.
You would not be unwise to size the main dwelling feeder in accordance with the maximum load that it may eventually carry even if the present load does not draw that much. The main breaker must be sized to the ampacity of the Service Lateral conductors which we already know are to be two hundred ampere. That means that the main dwelling feeder would need to be at least that large. Size the main dwelling feeder for the full 200 amperes at a voltage drop of 3% or less to get an acceptable efficiency of operation. Since you pay for any power consumed by voltage drop on the load side of the meter limiting the voltage drop in that feeder will limit your cost for wasted power. That having been said however the difference in voltage drop between 4/0 and 250MCM AL is half a percent and the difference in cost between the two cables is huge 250 SER Al was $27 a foot verses less then half of that for 4/0 SER AL. I'd check the price of individual UF conductors in 250 MCM Al. Remember also that it is generally a bad idea to use AL conductors uninsulated in earth so direct burial of Quadplex AL would not work. Pulling it into PVC conduit would work well if the price works out better.

On a separate issue you will want to exercise special care in grounding the pedestal service. The minimum acceptable electrode system is two eight foot rods driven six feet apart. Let me suggest that you run twenty feet of bare number two in the bottom of the feeder trench with the ground rods driven through the bottom of the trench that full twenty feet apart. That and the installation of a secondary surge arrestor within the pedestal service enclosure will markedly improve your homes surge protection.
 
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