2025-07-15 00:00:00 leaDCalc Application is based on the Western Electric, Bell Laboratories, Bell System DC Power Lead Calculator which is in a circular slide rule format. Using allowable voltage drops specifically designed for telephone company central office direct current power plants and distribution wiring. The application references 48 volt battery systems but also works for other direct current voltages such as 24 volt. When using for 24 volts or other, choose by the required loop voltage drop instead of the specific section of the circuit. Notes: 51. Voltage drop and wire size calculations are based on 2.00 volt LOOP drop from the power plant battery to the load equipment and return. 1.75 Final Volts Per Cell or 40 volts min. operating volts at the equipment for nominal 48V systems.
 (40 + 2 = 42 / 24 = 1.75fvpc) 

 52. LOOP length is used in the calculations, often the battery and returns are unequal. The result VD is shown as ONE WAY.