WireGaugeCalc Free calculator · NEC cited · works offline
Grounding Wire Size
Grounding wire size is quick with WireGaugeCalc, since the calculator matches the equipment grounding conductor to the overcurrent device protecting the circuit.
You enter the breaker or fuse rating and the conductor material, and the tool returns the minimum ground size.
So you can size the ground without second-guessing the table on the truck.
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 Ground Wire Size Is Set
The equipment grounding conductor is sized from the rating of the overcurrent device ahead of the circuit, so a larger breaker means a larger ground.
Conductor material changes the answer, since aluminum grounds run a size larger than copper for the same breaker.
What Decides the Equipment Ground Wire Size
A few inputs drive the minimum ground:
- Rating of the overcurrent device protecting the circuit
- Conductor material, copper or aluminum
- Whether the conductors were upsized for voltage drop
- Whether the ground is for a branch circuit or a feeder
- Any minimum size set for the application
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 ground wire size do I need for a 50 amp breaker?
The equipment grounding conductor is sized from the 50 amp overcurrent device rating. Enter 50 amps and your conductor material and the calculator returns the minimum ground size.
Does the ground wire size change if I upsize the circuit conductors?
Yes, since when conductors are increased in size for voltage drop the equipment ground is increased proportionally. Verify the result 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.