WireGaugeCalc Free calculator · NEC cited · works offline
What Gauge Wire To Ground A Generator
What gauge wire to ground a generator is simple with WireGaugeCalc, since you enter the circuit rating and conductor material and it returns a grounding gauge.
It sizes the equipment grounding conductor from the overcurrent device ahead of the circuit, so the bonding path matches the fault current it must carry.
You get a defensible gauge in seconds, so the grounding and bonding work passes 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 generator grounding conductor is sized
The equipment grounding conductor is sized to the rating of the protective device, so a 50A circuit and a 100A circuit return different gauges.
Copper and aluminum carry fault current differently, so the tool returns a larger aluminum gauge to match the same copper rating.
What the generator grounding calculator needs
Provide these and it returns the gauge:
- Rating of the overcurrent device feeding the circuit
- Copper or aluminum grounding conductor
- Whether it is an equipment ground or electrode conductor
- Conductor type such as bare or insulated
- Number of poles on the supply circuit
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
Is the grounding conductor the same size as the circuit conductors?
Usually no, since the equipment grounding conductor is sized to the overcurrent device rather than the load amps. It is often smaller than the supply conductors but never below the minimum the rating requires.
Does a portable generator still need a grounding conductor?
It depends on how the generator is connected and whether it is a separately derived system. Confirm the setup against the current NEC and your local authority having jurisdiction, since bonding rules change with cord-and-plug versus transfer-switch installs.
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.