WireGaugeCalc Free calculator · NEC cited · works offline
Hp To Flc
Hp to flc is simple with WireGaugeCalc, which converts motor horsepower to full-load current using the NEC motor tables.
You pick the horsepower, the voltage, and single or three phase, and the tool returns the full-load current value used for sizing.
So you have the FLC needed to size conductors and overloads without flipping through code tables.
Open the calculatorEnter any two values and read the rest.
Ohm’s law: V = I × R and P = V × I. Field aid only, verify against the current NEC and your local authority having jurisdiction.
Why Full-Load Current Comes From The Tables
Motor branch circuits are sized from the NEC full-load current tables, not the nameplate amps, since 430.6 directs you to use those listed values for conductor and device sizing.
Horsepower, voltage, and phase together fix the table value, so a 15 hp three phase current draw at 230 volts lands near 42 amps in the standard table.
The tool reads the matching row so the conversion is consistent with the code basis inspectors use.
What The FLC Number Feeds Into
Once you have full-load current, it drives the rest of the motor circuit:
- Conductor sizing at 125% of FLC for a single continuous motor
- Overload protection sized from the nameplate, checked against FLC
- Branch circuit short-circuit and ground-fault device sizing
- Three phase versus single phase, since phase changes the current draw
- Voltage, because higher voltage lowers current for the same horsepower
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
Why not just use the motor nameplate amps for sizing?
NEC 430.6(A) says to size conductors and overcurrent devices from the table full-load current, while overloads are sized from the nameplate. Always verify the method against the current NEC and your local authority having jurisdiction.
What is the current draw of a 15 hp three phase motor?
At 230 volts the NEC table lists about 42 amps, and at 460 volts it drops to roughly 21 amps. Use the table value for your actual voltage rather than a calculated estimate.
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.