Voltage Drop Calculator

Inputs

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Single-phase/DC uses a two-conductor path. Three-phase uses the balanced line-to-line shortcut.
Uses 75 C resistance constants: copper K=12.9, aluminum K=21.2 ohm-cmil/ft.
Conductor circular-mil area used for voltage drop. This is not an ampacity selection.
One-way distance from source to load, not round-trip length.
ft
Use direct amps when known, or derive balanced load current from kVA and voltage.
Load current in amperes.
A
Line-to-line voltage for three-phase, or source voltage for single-phase/DC.
V
Used for the max-length and suggested-area outputs. Common design screens use 3% for branch or feeder and 5% total.
%

Results

Default result
Edit inputs
Voltage drop(VD)
2.63%
Pass

At or below the 3% target.

Also computed

Voltage lost(V_drop)3.161V

Load-end voltage(V_load)116.84V

Load current used(I)16A

direct current input

Direct input current, or derived from kVA and phase.

Max one-way length(L_max)56.95ft

For the selected wire and target percent drop.

Suggested conductor area(CM_min)Pass6.53kcmil

nearest listed size: #12 AWG

Selected conductor area(CM)6.53kcmil

#12 AWG

Method notes 3 notes
  • single-phase shortcut using copper conductor constant and one-way length.
  • Load current is used directly as entered.
  • This screens voltage drop only. It does not check ampacity, insulation temperature, conduit fill, derating, equipment grounding conductors, termination ratings or local code requirements.

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