Residential Electrical calculator
NEC Table 220.55 Column C Calculator
This NEC Table 220.55 Column C calculator is intentionally narrower than a full NEC Article 220 calculator. Enter range count, rating basis, service configuration, phase-pair information when applicable, and line-to-line voltage to read the Column C demand, Note 1 adjustment, per-phase basis, and line current for the selected installation.
Updated August 17, 2026
NEC Table 220.55 Column C lookup: choose the range count or 3-phase, 4-wire basis count first, then apply Note 1 and convert the demand to line current. For 3-phase feeders, the calculator uses twice the maximum number connected between any two phases.
Method path: range count + rating basis -> Column C and Note 1 review -> 3-phase 4-wire basis if selected -> line-current conversion
Enter the range count, rating basis, and service configuration below to screen NEC Table 220.55 Column C demand and line current without turning this page into a full Article 220 service calculator
Source: NFPA 70, National Electrical CodeOpens in a new tab | Last reviewed: 2026-08-04
Final installation decisions must use the adopted NEC edition, equipment listings, and AHJ requirements.
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Field kit
Tools for demand worksheet notes
Use the range-demand result as a worksheet value, then compare simple documentation and verification tools.
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How to Use
NEC 220.55 range demand calculator scope
Use this calculator when the job is to screen household range or cooking-appliance demand under NEC Table 220.55. If the query is NEC Table 220.55 Column C values, apartment feeder checks, or a 3-phase, 4-wire range-demand screen, this page is the right owner. It does not replace a full dwelling service calculation under the rest of Article 220.
1. Enter the appliance count and the rating basis
- Number of Cooking Appliances is the actual number of household ranges or equivalent cooking appliances being served.
- Individual Rating or Note 2 Average should be the common appliance rating. If the appliances are unequal and fall in the Note 2 range, first calculate the required average rating and enter that averaged value here.
- Line-to-Line Voltage is used only to convert the screened demand to current. It does not change the Table 220.55 lookup itself.
2. Choose the right feeder or service basis
- Single-Phase Household Cooking Load uses the actual appliance count for the Table 220.55 lookup.
- 3-Phase, 4-Wire Feeder or Service uses twice the maximum number connected between any two phases. If you do not know the actual phase distribution, the calculator assumes the most balanced arrangement allowed by the appliance count and tells you that assumption in the warning text.
3. Read the demand results in the right order
- Base Column C Demand is the published Table 220.55 demand before any Note 1 increase.
- Adjusted Table 220.55 Demand applies the Note 1 increase when the entered rating basis is above 12 kW.
- Calculated Line Current converts that demand into current using the voltage you selected.
- On the 3-phase, 4-wire path, the calculator also shows the per-phase demand basis and equivalent 3-phase load used for the line-current conversion.
Table 220.55 Column C reference and calculator match
The selected result depends on range count, rating basis, service configuration, phase-pair information, and voltage. The rows below are a reference for the Table 220.55 method after you identify the correct basis count.
| Basis count | Column C demand | Why it matters |
|---|---|---|
| 1 | 8 kW | Common single range screen |
| 4 | 17 kW | Typical small multifamily feeder check |
| 8 | 23 kW | Common 3-phase equivalent basis count in Annex D examples |
| 25 | 40 kW | Last direct lookup row before the published formulas start |
| 26-30 | 15 kW + 1 kW for each range | Use the published formula instead of inventing a straight-line extension |
| 31 and over | 25 kW + 0.75 kW for each range | Applies once the basis count moves above 30 |
Use the 3-phase, 4-wire preset for a worked comparison
To review a multifamily feeder with a known heaviest phase pair, choose the 3-phase preset above or enter your own range count, phase-pair count, rating basis, and voltage. The calculator will show the basis count, Column C demand path, per-phase basis, equivalent 3-phase load, and line current together so the method is tied to your inputs.
Important limits to keep in mind
- This page stays on the Table 220.55 household cooking load problem. It does not calculate lighting demand, receptacle demand, dryers, water heaters, HVAC, or optional-method dwelling loads.
- For household cooking appliances over 1.75 kW through 8.75 kW, Note 3 permits alternate Column A or Column B demand-factor methods. This calculator is designed for the Column C range-demand path.
- For mixed appliance ratings above 8.75 kW through 27 kW, calculate the Note 2 average first. The screen does not build that average for you.
Common Applications
Frequently Asked Questions
How do you handle 3-phase, 4-wire range demand under NEC 220.55?
For the adopted NFPA 70 edition, verify the Table 220.55 notes that apply to a 3-phase, 4-wire feeder or service. This calculator screens the common method by using twice the maximum number connected between any two phases as the table basis count, then showing the per-phase demand basis, equivalent 3-phase load, and line-current conversion so the source-table step remains visible.
Does this page calculate all Article 220 demand factors?
No. This route is intentionally narrowed to Table 220.55 household cooking demand. It does not calculate the rest of a dwelling service, optional-method load calculations, lighting demand, receptacle demand, or major fixed appliance demand outside the range-load problem.
What should I enter when appliances have different ratings?
Use the adopted NFPA 70 edition and the appliance nameplate ratings to confirm whether Table 220.55 Note 2 applies. The calculator expects the already-reviewed average rating as the input, then applies its Column C/Note 1 screen; it does not decide whether a local amendment, appliance listing, or broader Article 220 method changes the final demand basis.
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