WireGaugeCalc Free calculator · NEC cited · works offline
Gauge Wire For 240 Volt
gauge wire for 240 volt is quick with WireGaugeCalc, since you enter the load amps and it returns the smallest gauge that carries them.
It checks the load against NEC 310.16 ampacity for your material and terminal temperature, so the conductor matches the breaker.
The payoff is a 240 volt circuit sized once, with no second-guessing at rough-in.
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 Load Amps Drive The 240 Volt Conductor
A 240 volt circuit still sizes off amperes, so the volts set the appliance and the current sets the wire.
Copper and aluminum split here, since aluminum needs a larger gauge for the same amps.
The 75 degree C column usually governs, as that is the rating on most 240 volt equipment terminals.
What The 240 Volt Wire Sizing Needs
Feed the tool the circuit basics and it returns the gauge:
- Load in amperes, or the appliance nameplate rating
- Conductor material, copper or aluminum
- Terminal temperature, 60, 75, or 90 degrees C
- Sizes against NEC 310.16 ampacity
- Confirms the gauge supports the matching breaker
- Flags small-conductor limits on 14, 12, and 10 AWG
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 gauge runs a 30 amp 240 volt circuit?
A 30 amp 240 volt circuit usually takes 10 AWG copper at the 75 degree C rating, since that gauge carries 30 amps. Verify the load and continuous-use factors against the current NEC and your local authority having jurisdiction.
Do I size differently for 240 volt versus 120 volt?
The gauge follows the amperes, not the voltage, so the same load amps need the same wire on either system. Voltage only changes which equipment and breaker pole count you use.
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.