WireGaugeCalc Free calculator · NEC cited · works offline
Solar NEC Wire Ampacity Calculator
Solar nec wire ampacity calculator is simple with WireGaugeCalc, since you enter the PV conductor and the tool reads its rated current from the NEC table.
It applies the termination column and material you select, so the ampacity matches what the inverter and combiner lugs can accept.
You get a clear value to check your PV source and output conductors against the overcurrent device.
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.
Ampacity For PV Source And Output Circuits
The calculator reads the rated current for copper or aluminum from the 75 or 90 degree column, since most PV equipment terminations are rated at those temperatures.
It applies ambient and rooftop conditions through correction factors, so conductors on hot roofs are not overrated.
What The PV Ampacity Result Uses
Several solar-specific inputs shape the ampacity figure:
- PV conductor size in AWG or kcmil
- Copper or aluminum material
- Termination temperature column, often 75 degrees C
- High rooftop ambient temperature for correction
- Number of current-carrying conductors in the run
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
Why are rooftop PV ambient temperatures so important?
Conductors on or near a roof can run far hotter than free air, which drops their corrected ampacity. The calculator applies the ambient factor so your PV conductors stay within their rating.
Does this cover the PV continuous-current sizing factor?
It returns table ampacity, and you still apply the continuous-load and PV multipliers before comparing to the overcurrent device. Verify the final sizing 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.