WireGaugeCalc Free calculator · NEC cited · works offline
Cable Size For 500 Amps
Cable size for 500 amps is fast with WireGaugeCalc, since the tool reads NEC 310.16 ampacity and returns the conductor that carries the load.
You enter the amperage, the conductor material, and the termination temperature, so the result matches how the breaker and lugs are actually rated.
The payoff is a sized conductor you can take straight to the takeoff and the inspection.
Open the calculatorSmallest conductor whose ampacity meets the load, NEC Table 310.16. Field aid only, verify against the current NEC and your local authority having jurisdiction.
How The 500 Amp Conductor Is Sized
A 500 amp load needs a conductor rated at or above 500 amps in the correct termination column, so the calculator pulls that ampacity directly from NEC 310.16.
Copper and aluminum hit 500 amps at different sizes, so the tool adjusts the gauge as soon as you switch the material.
Large feeders at this current are often run in parallel sets, so the result shows whether a single conductor or paralleled runs fit.
What Drives The 500 Amp Result
Three inputs decide the conductor at 500 amps:
- Conductor material, since copper carries more amps per size than aluminum
- Termination temperature, since the 60C, 75C, and 90C columns give different ampacity
- Single run versus parallel sets per NEC 310.10
- The 500 amp load the conductor must carry continuously
- Insulation type tied to the temperature rating
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 copper size carries 500 amps?
In the 75C column of NEC 310.16, a 700 kcmil copper conductor reaches 500 amps. Many installers instead run parallel sets of smaller conductors to ease pulling. Verify the size against the current NEC and your local authority having jurisdiction.
Can I run parallel conductors for a 500 amp feeder?
Yes, NEC 310.10 allows paralleling conductors 1/0 and larger, so two sets of 250 kcmil copper can together carry 500 amps. Each parallel conductor must be the same length and material.
Does termination temperature change the 500 amp cable size?
Yes, since the breaker and lug ratings set which ampacity column you use. Most 500 amp terminations are rated 75C, so size from the 75C column unless the equipment is listed otherwise.
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.