WireGaugeCalc Free calculator · NEC cited · works offline
Non-Current Carrying Conductor Sizing
Non-current carrying conductor sizing is fast with WireGaugeCalc, since the app reads the circuit overcurrent device and returns the matching equipment grounding conductor.
You enter the breaker rating and the conductor material, and the calculator pulls the size from the NEC 250.122 table so the ground keeps pace with the phase conductors.
The payoff is a grounding conductor that clears a fault quickly without a manual table lookup.
Open the calculatorAllowable ampacity from NEC Table 310.16 at the chosen termination temperature. Field aid only, verify against the current NEC and your local authority having jurisdiction.
How Equipment Grounding Conductor Sizing Works
The equipment grounding conductor is sized to the rating of the overcurrent device ahead of the circuit, not to the load current.
As the breaker rating goes up, the required ground gets larger so it can carry fault current long enough to trip the device.
Copper and aluminum read from different columns, so the calculator separates them to keep the size honest.
What Drives Non-Current Carrying Conductor Sizing
A few inputs set the result for a grounding or bonding conductor:
- Overcurrent device rating, which is the anchor for the NEC 250.122 lookup
- Conductor material, since aluminum runs a step larger than copper
- Upsized phase conductors, which require a proportional increase in the ground
- Parallel runs, where each raceway carries its own full-size grounding conductor
- Conductor type, so insulation and use match the installation
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 a non-current carrying conductor have to grow when I upsize the phase conductors?
Yes, when phase conductors are increased in size for voltage drop, the equipment grounding conductor is increased proportionally per NEC 250.122(B). The calculator flags this so the ground tracks the larger ungrounded conductors.
Is the ground sized to the breaker or to the load?
It is sized to the rating of the overcurrent device protecting the circuit, not the load current. Confirm the result against the current NEC 250.122 table and your local authority having jurisdiction before you pull wire.
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.