WireGaugeCalc Free calculator · NEC cited · works offline
70 Amp Service Wire Size
70 amp service wire size is simple to confirm with WireGaugeCalc.
Enter the 70 amp rating, conductor material, and termination temperature, and the tool returns the conductor that carries the load under NEC 310.16.
So you can spec the feeder before you cut a single length.
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.
Sizing The Feeder For A 70 Amp Service
The tool reads the smallest conductor that carries 70 amps in the column set by your terminations.
Since copper and aluminum differ, the calculator holds the material you picked and reports the matching AWG or kcmil.
It also flags when grounded and grounding conductors need their own sizing review.
What Goes Into The 70 Amp Result
The calculator weighs each of these:
- The 70 amp service rating
- Conductor material, copper or aluminum
- Termination temperature, usually 75 degree C
- Run length, since long runs may add voltage drop
- The conductor size that satisfies the ampacity table
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 size copper wire fits a 70 amp service?
A 70 amp load typically calls for a conductor read from the 75 degree C column of NEC 310.16. Confirm the exact size against the current NEC and your local authority having jurisdiction, since service rules can vary.
Should I upsize for voltage drop on a long service run?
If the run is long, voltage drop can push you to a larger conductor than ampacity alone requires. The tool lets you check the run length so you can decide before ordering 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.