WireGaugeCalc Free calculator · NEC cited · works offline
Nec 220 Load Calculations
Nec 220 load calculations are simple with WireGaugeCalc, which totals general lighting, receptacle, and fixed appliance loads in volt-amperes.
It applies the Article 220 demand factors so the calculated load reflects what the service actually draws, not the raw sum.
You end up with a service or feeder size backed by the math, ready to defend on a plan review.
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.
From Connected Load To Demand Load
General lighting is figured at the volt-amperes per square foot from NEC Table 220.12, since that sets the base load.
Small-appliance and laundry circuits are added at the fixed 1500 VA each, then demand factors trim the lighting total.
Largest loads like ranges and dryers use their own demand tables, so the final service load stays realistic.
Steps In A Standard Dwelling Calculation
The app walks the standard method from NEC 220 Part III in order:
- General lighting at 3 VA per square foot
- Two small-appliance circuits plus one laundry at 1500 VA each
- Lighting and receptacle demand factor from Table 220.42
- Appliance, range, and dryer demand additions
- Largest motor load added at 25% per NEC 430.24
- Total divided by service voltage to get amps
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 difference between the standard and optional method?
The standard method in Part III sums loads with category demand factors. The optional method in 220.82 applies a single tier of demand to the total for a single dwelling. Verify which method your jurisdiction accepts against the current NEC and the local authority having jurisdiction.
Do I add the largest motor at 125 percent?
In a service or feeder calculation you add 25% of the largest motor load, since that motor is already counted once and NEC 430.24 requires the extra 25% for its contribution.
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.