WireGaugeCalc Free calculator · NEC cited · works offline
150 Amp Service Wire Size
150 amp service wire size is fast with WireGaugeCalc, since you pick the conductor material and it returns the gauge.
The tool reads NEC ampacity at the 75 degree C termination column, so the result matches how breakers and lugs are rated.
You get a copper or aluminum size that carries the service safely to the panel.
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.
Minimum Wire Size For A 150 Amp Breaker, By Material
A 150 amp service commonly uses 1/0 copper or 2/0 aluminum, since those land on the 150 amp row at the 75 degree C termination column.
Aluminum runs larger than copper for the same amperage because it carries less current per size, so the tool shows both options.
Long underground or overhead runs may need an upsize for voltage drop, and the calculator flags that when distance grows.
Inputs Behind The 150 Amp Service Conductor Size
Set the service details and the gauge follows:
- Service rating of 150 amps
- Copper or aluminum conductor material
- Termination temperature column at 75 degrees C
- NEC 310.16 ampacity lookup
- Run length for voltage drop on long feeders
- Minimum wire size for the 150 amp breaker
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 is the minimum wire size for a 150 amp breaker?
It is commonly 1/0 copper or 2/0 aluminum at the 75 degree C termination column under NEC 310.16. Confirm the final size against the current NEC and your local authority having jurisdiction, since service entrance rules can differ.
Why does aluminum need a larger size for 150 amp service?
Aluminum has higher resistance than copper, so it carries less current at the same gauge and must be sized up to reach 150 amps. The calculator gives both the copper and aluminum numbers.
Do long service runs need bigger conductors?
Yes, a long run can drop too much voltage, so you may upsize the conductors to stay near the 3% guideline. Enter the distance and the tool will indicate when an upsize helps.
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.