doing a new home with a underground service that is about 250 feet long,could anyone show me how to calculate wire size?
thank you,
patrick regan

Try this: http://www.electrician.com/vd_calculator.html

That very simple calculator is missing both ambient and terminal temperatures ,raceway types and power factor...all having a major factor in VD computation.

Try this one as it takes everything into consideration inclusive of raceway types and temperatures. Also the VD formula is not a simplistic 2KID but rather IEEE 141 exact formula.
http://www.dolphins-software.com/Volts_Setup.exe

[This message has been edited by DiverDan (edited 07-28-2005).]