NEC Table 220.55 Column C Calculator

What this NEC 220.55 range-demand calculator covers

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 quick reference

This section is meant for searches around demand factors for household electric ranges and Column C values for number of ranges. Use the basis count first, then apply any rating adjustment notes before converting the selected demand to feeder or service current.

Worked 3-phase, 4-wire example

Suppose a multifamily feeder serves 10 single-phase household ranges and the heaviest phase pair carries 4 of them.

1. Twice the maximum connected between any two phases = 8.
2. Table 220.55 Column C for 8 gives 23 kW.
3. Per-phase demand basis = 23 kW / 2 = 11.5 kW.
4. Equivalent 3-phase load = 11.5 kW x 3 = 34.5 kW.
5. At 208 V, line current = 34,500 / (208 x sqrt(3)) = about 95.8 A.

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 route intentionally stays on the Column C workflow because that is the dominant search intent for this page.
• 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.