Q:
What Is the Formula for Calculating Cable Size?
A:
Quick Answer
The formula for calculating cable size for single phase circuits is wire circular mils = (conductor resistivity)(2)(amps)(one way distance in feet) / allowable voltage drop. This formula is based on Ohm's Law.
Continue ReadingFull Answer
For three-phase circuits, the formula varies. It is wire circular mils = (conductor resistivity)(2)(amps)(one way distance in feet)(.866) / allowable voltage drop. In standard formulas, the conductor resistivity for copper is 11.2 and for aluminum, it is 17.4 when the temperature is 127 degrees Fahrenheit. The National Electric Code only allows a maximum voltage drop of 3 percent on a main circuit branch, and this should be taken into account when determining cable size.
Learn more about MeasurementsSources:
Related Questions
-
Q:
What Is the Distance of One City Block?
A: The standard distance of one city block is typically 311 feet long. The length varies based on the city and the specific street. Full Answer >Filed Under: -
Q:
How Do You Convert Feet Into Linear Feet?
A: Assuming a distance is measured in a straight line in feet, the number of feet equals the number of linear feet. If the number of feet traveled is not in a... Full Answer >Filed Under: -
Q:
What Are the Different Units Used to Measure Distance?
A: Common units for measuring distance include meters, feet, inches, yards and miles. The metric system uses the word "meter" along with a prefix that designa... Full Answer >Filed Under: -
Q:
How Many Feet Does 1 Yard Equal?
A: A 1-yard distance is equivalent to 3 feet. If a driveway is 15 yards long, simply multiply 15 by 3 to find the number of feet. The length of a 15-driveway ... Full Answer >Filed Under:
