wire size

[cesenergy]

I have an underground service 575 feet long from utility transformer to home underground 120/240 volt 200 Amp can anyone tell me what size aluminum wire and what type I should run in conduit. I ran a 4" PVC Conduit so sky is the limit but worried about voltage drop. Customer refused a primary due to cost I know bad call but could not convince him and utility ok'd secondary Any help out there I am thinking 250

[iwire]

It is a difficult question to answer and it is as much a guess as anything else.

Two factors must be decided on.

1) How much voltage drop will the customer be willing to live with.

2) What is the actually load on the service today and in the future.

[infinity]

As Bob pointed out there are variables. Here is a link to a voltage drop calculator. You can play around with the numbers. For kicks I plugged in 400kcmil AL with 120 amp load and came up with a voltage drop of 2.7%.

http://www.electrician2.com/calculators/vd_calculatoradv.htm

[celtic]

I came up with 500's

http://www.elec-toolbox.com/calculators/voltdrop.htm

EDIT:
I arrived at the 500's by entering ONLY the information given.

FWIW, here's anothercalculator...compliments of this very website:
http://www.mikeholt.com/studies/vd.htm

[iwire]

I got sidetracked but I was going to add that it may be good to run the numbers a few ways.

Less than 3% drop with a full 200 amps.

Less then 3% drop with the calculated load.

Less than 5% drop with the calculated load.

Price the job each way and bring it to the customer let them see what it will cost them. Let them make the decision and than sign for it.

[cesenergy]

It is a difficult question to answer and it is as much a guess as anything else.

Two factors must be decided on.

1) How much voltage drop will the customer be willing to live with.

2) What is the actually load on the service today and in the future.

1800 square foot home not much load would take a 100 amp service if transformer was closer

[cesenergy]

its a friends house so I just want to do whatever I can to help its a small house and most of the appliances are propane so there is not much load. He already had the secondary planned so It was to late to help him with the correct decision for a primary

[haskindm]

Why does everyone try to avoid doing a load calculation????!!!!!!
Sit down with Article 220 and do a load calculation on the entire house. If it is a small home with mostly gas appliances it should take you less than 20 minutes to do a complete calculation. Once you have the calculated load, do a voltage drop calculation. Then there will be no guessing, no "it probably should be OK", and you can tell your friend exactly what he needs to have installed with the calculation to back you up.

[bkludecke]

I agree with haskindm. Do the load calc. There is an easy form on this MIKE holt website that even does the math for you! I usually bump the final number up 10% or at least one wire size to accomdate future loads.

Bob on the left coast.

[cesenergy]

97 Amps with load calc

[haskindm]

Looks like 250 kcmil will give you abot 2.4% voltage drop. As long as your branch circuits aren't too long you should be in great shape.

[cesenergy]

Thank You haskindm

[iwire]

1800 square foot home not much load would take a 100 amp service if transformer was closer



Your installing a 200 amp service over a 100 amp service because of the distance?

[cesenergy]

No future expansion is the reason for the 200 amp I am more concerned with my reduced neutral if I use Triplex all my suppliers sell Triplex 25mcm al with a 3/0 reduced neutral Do you think this will effect the voltage drop

[cesenergy]

sorry 250mcm aluminum

[hardworkingstiff]

No future expansion is the reason for the 200 amp I am more concerned with my reduced neutral if I use Triplex all my suppliers sell Triplex 25mcm al with a 3/0 reduced neutral Do you think this will effect the voltage drop

If you had all of your 120-volt loads on one phase, yes. But since I feel confident you will balance them on the two phases the neutral will only carry the unbalanced load which should be significantly less and not cause any problems.