WireGaugeCalc Free calculator · NEC cited · works offline
150 Amp Motor Ground Wire Size
150 amp motor ground wire size is fast with WireGaugeCalc, since you pick the overcurrent device rating and conductor material and read the equipment grounding conductor result.
The calculator uses the NEC 250.122 table so the ground matches the breaker protecting the motor circuit.
You get the right copper or aluminum gauge in seconds, so the install passes inspection.
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 150a EGC By Breaker Rating
The equipment grounding conductor is sized from the rating of the overcurrent device, not the load current.
For a 150 amp breaker, NEC 250.122 calls for 6 AWG copper or 4 AWG aluminum.
If you upsize the phase conductors for voltage drop, the ground must be increased in proportion.
What WireGaugeCalc Checks For The Motor Ground
Enter a few facts and the tool returns the grounding conductor size for the motor:
- Overcurrent device rating set to 150 amps
- Copper or aluminum conductor material
- NEC 250.122 table value for the breaker size
- Proportional increase when phase conductors are upsized
- Clear gauge result for copper and aluminum
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 the motor ground wire sized from the breaker or the motor FLA?
The equipment grounding conductor is sized from the overcurrent device rating per NEC 250.122. For a 150 amp breaker that is 6 AWG copper or 4 AWG aluminum.
Do I need to upsize the 150a EGC if I increase the phase conductors?
Yes. When the ungrounded conductors are increased in size, the equipment grounding conductor must be increased in proportion to their circular mil area. Verify the result 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.