AN ENGINEERING SELECTION FOR SIZE OF LONG CONDUCTORS CONSIDERING FACTORS IN ADDITION TO NEC

Long power cables and large machines require different application techniques from most electrical wiring. Selection of conductor size must consider insulation temperature as well as voltage drop. The NEC is commonly used for determining conductor size. It is primarily based on current carrying capacity, since this impacts the temperature of the insulation.
However, operational considerations demand the consideration of other factors. The procedure is primarily a mathematical design practice that is seldom considered in manual calculations. We have applied numerous considerations to develop a simple relationship that can be readily applied in routine designing. It incorporates wire diameter, length, current, number of phases, and temperature correction, with permissible voltage drop.