WireGaugeCalc Free calculator · NEC cited · works offline
480 Voltage Drop Calculator
480 voltage drop calculator is simple to use with WireGaugeCalc.
Enter the load amps, the one-way run length, and the conductor size, and it returns the volts dropped and the percent for your 480-volt circuit.
You see at a glance whether the run stays inside the 3% branch-circuit target.
Open the calculatorUses Vd = (phase factor × K × I × L) / circular mils, K = 12.9 copper, 21.2 aluminum. Field aid only, verify against the current NEC and your local authority having jurisdiction.
What This Electrical Voltage Drop Calculator Shows
Long runs add resistance, so voltage falls before it reaches the load, and at 480 volts a small percentage still amounts to several volts.
This electrical voltage drop calculator reports the drop in both volts and percent so you can judge it against the 3% guideline.
Since copper and aluminum carry different resistance, the tool lets you switch material and watch the result change.
Inputs For The Line Voltage Drop Calculator
Give the calculator a few field values and it does the rest:
- Load current in amps
- One-way run length in feet
- Conductor size and copper or aluminum
- Single-phase or three-phase 480-volt system
- Result in volts and percent of 480
- A flag when the drop passes 3%
One app for every NEC calculation
WireGaugeCalc keeps the calculations you reach for most in one place:
- Voltage drop and wire sizing for any run
- Conduit fill for EMT, PVC, and RMC
- Box fill and junction box sizing
- Ampacity and temperature derating
- Motor circuit and load calculations
- Conduit bend offsets and saddles
Built for the field, works offline
The whole app runs on your phone, so it keeps working in a basement, an attic, or a job site with no signal.
There is no account to create and nothing to load. Open it, run the number, and get back to work.
- No signup and no signal needed
- Answers in a tap, not a spreadsheet
- Same tool on phone, tablet, and desktop
Every result cites the NEC article
Each answer shows the table or formula it came from, so you can check the method and learn the code as you go.
That makes the app useful on the job and during exam prep, since the reasoning is right next to the number.
Switch the code year your job runs on
Jurisdictions adopt the NEC at different times, so you can match the calculation to the code in force:
- NEC 2017, 2020, and 2023 tables
- Copper and aluminum conductors
- 60, 75, and 90 degree C terminations
- Single-phase and three-phase systems
Run the number, then get back to work
Stop flipping through a paper book or hopping between calculator sites. Enter your values, read the code-cited answer, and move on. Free to use, no signup.
Open the calculatorFrequently asked questions
What voltage drop is acceptable on a 480-volt circuit?
The NEC recommends keeping branch-circuit drop near 3% and the combined feeder and branch drop near 5%. These are informational guidelines, so verify the limits with the current NEC and your local authority having jurisdiction.
Does copper or aluminum drop more voltage on a 480 run?
Aluminum has higher resistance per foot, so it drops more voltage than copper of the same size. The line voltage drop calculator lets you compare both and upsize the aluminum to match.
How do I cut the drop on a long 480-volt feeder?
Increase the conductor size, shorten the run, or reduce the load. Upsizing one size at a time usually brings the percent back under target.
Is WireGaugeCalc free to use?
Yes. Every calculator is free to run with no signup. A paid tier adds saved projects, PDF reports, and extra code years, but the core math stays free.
Does it work without internet?
Yes. The app runs on your device, so it keeps working with no signal on a job site, in a basement, or in an attic.
Are the results code accurate?
Results follow published NEC tables and standard formulas, and each answer shows the article it came from. It is a field aid, not a stamp of approval, so verify against the current code and your local authority before you wire anything.
Which NEC code year does it use?
You can switch between NEC 2017, 2020, and 2023, since jurisdictions adopt the code at different times. Pick the year your job runs on.