WireGaugeCalc Free calculator · NEC cited · works offline
150a Wire Size
150a wire size is simple to confirm with WireGaugeCalc.
You enter the 150 amp load, conductor material, and termination temperature, and the calculator returns the conductor that meets NEC ampacity.
So your 150 amp feeder or subpanel is sized right before the pull.
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.
Common Conductors For A 150 Amp Feeder
At 75 degrees C, 1/0 copper carries 150 amps, so it is the usual copper pick for a 150 amp feeder.
Aluminum runs larger, since 2/0 aluminum reaches 150 amps under the 75 degrees C column.
The calculator confirms the size against your exact material and column.
What Sets The 150 Amp Conductor Size
The calculator weighs these to land the gauge:
- Conductor material, copper versus aluminum
- Termination temperature column at the breaker and lugs
- Insulation type such as THWN-2 or XHHW-2
- Run length where voltage drop pushes the size up
- Ambient heat or conduit fill that triggers derating
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 1/0 copper enough for a 150 amp feeder?
Yes, 1/0 copper is rated 150 amps in the 75 degrees C column, so it usually fits a 150 amp feeder with standard terminations. Verify the terminal ratings on both ends.
What aluminum size do I need for 150 amps?
2/0 aluminum carries 150 amps at 75 degrees C and is the common aluminum choice. Confirm the size and any derating 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.