WireGaugeCalc Free calculator · NEC cited · works offline
Sizing Ground Wire
Sizing ground wire is simple with WireGaugeCalc, since you enter the breaker rating and conductor material and it returns the size.
The tool reads the NEC grounding tables for you, so the equipment grounding conductor matches the overcurrent device.
You get the correct gauge to land in the panel without guessing from memory.
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.
Grounding Wire Conductor Size By The Overcurrent Device
The equipment grounding conductor is sized by NEC Table 250.122 against the breaker rating, so a 20 amp circuit and a 60 amp circuit need different grounds.
If you upsize the ungrounded conductors for voltage drop, the ground must be upsized in proportion, since the code ties the two together.
WireGaugeCalc applies that rule automatically so the grounding wire conductor size stays compliant.
What Goes Into Sizing The Ground Conductor
A few inputs return the right ground for the circuit:
- Overcurrent device rating in amps
- Copper or aluminum conductor material
- Equipment grounding conductor per NEC 250.122
- Upsize factor when phase conductors are increased
- Grounding electrode conductor per NEC 250.66 for services
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
Does the ground wire size change if I increase the phase conductors?
Yes, when you upsize the ungrounded conductors for voltage drop or other reasons, NEC 250.122 requires the equipment grounding conductor to be increased proportionally. The calculator handles that ratio for you.
Is the grounding wire conductor size the same for copper and aluminum?
No, aluminum needs a larger gauge than copper for the same circuit. Pick the material in the tool, and verify the final size against the current NEC and your local authority having jurisdiction.
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.