redzilla
All tools

IP Addressing

Layer 2

Performance

Wireless

CCTV

Optical fiber

Power

Datacenter

AV

Voice

Diagnostics

Calculation

Security

Power

Voltage Drop

Enter the current, the one-way length and the source voltage and get the voltage drop (V and %), power loss and the minimum gauge that meets your target. Supports DC, single-phase and three-phase, in copper or aluminum. Resistive model: ignores reactance and temperature.

A
m

Distance from source to load (not the round trip). The calculation already doubles the conductor for DC/1φ.

V
System

DC and single-phase share the formula (round trip). In a balanced three-phase system the drop uses the √3 factor.

Conductor material
—

The label on the right shows the resistance of the chosen gauge in Ω/km at 20 °C.

Typical criterion: 3 % on branch circuits, 5 % overall (feeder + branch).

redzilla.cl — vdrop 
 
  
 
 
Voltage drop
 
—
 
—
 
 
 
Voltage at the load
 
—
 
—
 
 
 
Power loss
 
—
 
dissipated in the conductor
 
 
  
 
Recommended gauge
 
—
 
  
 
 Drop —  
 
 % —  
 
 Min. gauge —  
 
  
 
Drop by gauge 
 
 
  
GaugeΩ/kmDrop (V)Drop (%)
   
 
 
  meets the target
 exceeds the target

 
 
 How it is calculated · formulas and assumptions 
 
 1. DC and single-phase (1φ), accounting for
            the round trip: Vdrop = 2 · I · (L/1000) · R, with
R in Ω/km and L in meters.

 
 2. Balanced three-phase (3φ):
Vdrop = √3 · I · (L/1000) · R.

 
 3. Percentage:
%drop = Vdrop / Vsource · 100. Voltage at the load
= Vsource − Vdrop.

 
 4. Power loss:
P = I² · Rtotal, with Rtotal = 2·(L/1000)·R
for DC/1φ and ≈ √3·(L/1000)·R for 3φ.

 
 5. Aluminum is modeled as copper
× 1.64. Resistive model: it ignores the
            cable's reactance and the variation of R with
            temperature. For long runs or reactive loads, check your code.

 
 
 
 
 
Runs locally in your browser · no sign-up · nothing leaves your browser.