About
This app calculates direct current power lead sizes for telephone company central office power plants. It uses a circular slide rule format to determine allowable voltage drops and wire sizes based on specific system parameters.
What's New in leaDCalc
26.1
April 18, 2026
Version 26.1 Update new icon otherwise same old great power lead calculator.
Developer apps
FAQ
What is leaDCalc used for?
leaDCalc is used to calculate direct current (DC) power lead sizes and allowable voltage drops specifically for telephone company central office power plants. It's based on the historical Western Electric Co. Inc. Bell System DC Power Lead Calculator.
Does leaDCalc work with different DC voltages?
Yes, leaDCalc references 48-volt battery systems but also works for other DC voltages such as 24 volts. When using for other voltages, you select by the required loop voltage drop rather than a specific circuit section.
How does leaDCalc calculate wire size?
The application uses a formula that considers loop length, fuse or breaker size (at a specified percentage, e.g., 66% or 80%), and the desired voltage drop (VD) to determine the required wire size in circular mils (CM).
Is leaDCalc affiliated with T-Mobile or the Bell System?
No, leaDCalc explicitly states it is NOT affiliated with any person, company, or entity, including T-Mobile or the Bell System. It is meant as an informational guide based on historical calculations.
What is the voltage drop basis for leaDCalc?
Voltage drop and wire size calculations are typically based on a 2.00-volt loop drop from the power plant battery to the load equipment and return. This aligns with 1.75 final volts per cell for nominal 48V systems.
What does 'loop length' mean in leaDCalc?
Loop length refers to the total length of the conductor path from the power source to the load and back. The application uses this value because battery and return paths are often of unequal length.
Is leaDCalc suitable for AC systems?
No, leaDCalc is strictly for direct current (DC) systems, including charging and storage battery telephone systems. It is not intended for use with alternating current (AC) systems.
What is the update frequency for leaDCalc?
The latest version, 26.1, was last updated on April 18, 2026. This indicates a very infrequent update cycle, with the last known update being in the future.
