Feeder and Branch Circuit Voltage Drop Calculator
Estimate cumulative voltage drop through separate feeder and branch circuit segments using each segment’s load and conductor data.
Enter conductor and load values
Cumulative circuit voltage drop
About this calculator
Estimate cumulative voltage drop through separate feeder and branch circuit segments using each segment’s load and conductor data.
This version models two single-phase segments at the same nominal voltage. It is a resistance-only estimate and does not check ampacity, conductor sizing, reactance, or code compliance.
Method and assumptions
Each segment voltage drop is calculated independently from current, one-way length, listed conductor resistance, and a single-phase round-trip factor of two. Segment drops are summed and compared with the shared source voltage.
Resistance values use the site’s listed 75°C AC conductor data. Temperature adjustment is a first-order estimate; measured or manufacturer values for the installed conductor take precedence.
FAQs
Are listed conductor resistance values exact for an installed circuit?
No. Actual resistance depends on conductor construction, operating temperature, installation, connections, and parallel arrangement. Use project-specific manufacturer or engineering data when available.
Does this verify conductor ampacity or code compliance?
No. These tools estimate resistance, I-squared-R loss, or cumulative voltage drop only. Ampacity, conductor sizing, protection, installation, and local requirements need separate review.
Sources
Conductor resistance data is attributed in the calculation registry to Southwire cable specifications; verify conductor-specific data for the installed cable.