US utilities typically apply demand/diversity factors for single services, where that is a little unusual in NEC-land. Part of their rationale is that they use a shorter list of standardized ‘cookie-cutter’ construction materials, and can replace something of theirs that’s broken at 3AM if they ”need” to.
Some ‘engineering justification’ by utilities for small service-lateral conductors is not NEC 310-16 cable-insulation thermal problems contactors allow for, but 1.) Calculations are made so the customer won’t have a voltage-drop problem, and 2.) Conductor size is assigned by us to limit fault current at customer equipment.
Over time, if you get to know their estimators, you can deal with them a little. An argument I got into with a large utility a couple of decades ago was over their insistance on me installing 2-bolt ½-inch compression lugs in a 400-amp CT section…for 1/0 AWG AL. Their attitude can be: “Do it our way or no electric service. Case Closed—End Of Discussion.”
[This message has been edited by Bjarney (edited 10-05-2003).]
