k Constant For Voltage Drop

Centigrade Fahrenheit Square Inches Circular Mils Cost kwH Circular Mils
k Constant Voltage Drop 1 Phase Voltage Drop 3 Phase Voltage Drop Percent
Voltage Drop Multiple Legs Transformers 1 Phase Transformers 3 Phase AC Refrigeration 1 Phase
AC Refrigeration 3 Phase Conversion Home Electrician Math Home Electrician Education Home

k Constant for Voltage Drop

Time was when 10.4 ohms per circular mil foot was the constant for copper conductors. In an effort to be more accurate for various sizes of conductors, k is now calculated with this formula:

k = R (resistance of the conductor based on size from the NEC) times circular mils
divided by 1000.
(Be sure to use the R for uncoated conductor values since that is what is used for building wire.)

The result is the correct k for a specific conductor.

Here is a sample table of k values as provided in Reference Formulas Appendix

Find practice problems HERE.

Find audio support HERE.


Many electrician workbooks and practice exams are now available 
as digital downloads for immediate use. 
Click HERE to see what is available.

Products For Sale
2006-2011 David U. Larson
Companion Website to ElectricianEducation.com ,
2011NEC.com and
Other websites by David U. Larson which may be of interest: