NEC General Demand Factor Calculator

Calculate demand factors for general lighting (§120.42), electric clothes dryers (Table 120.54), and cooking ranges (Table 120.55) per NEC 2026 Art. 120.

NEC edition

Inputs

VA
units

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⚡ Test your knowledge
NEC Article 220 was renumbered in the 2026 code cycle. What is the new article number?
  • A. Art. 100
  • B. Art. 120
  • C. Art. 200
  • D. Art. 230
💡 NEC 2026 renumbered Article 220 (Branch-Circuit, Feeder, and Service Calculations) to Article 120.
Energy Management Systems were moved from Article 750 to which article in NEC 2026?
  • A. Art. 100
  • B. Art. 125
  • C. Art. 130
  • D. Art. 150
💡 NEC 2026 moved Energy Management Systems from Article 750 to Article 130.
Which NEC standard size overcurrent device comes after 90A?
  • A. 95A
  • B. 100A
  • C. 110A
  • D. 105A
💡 Per NEC §240.6(A), the standard sizes are …90, 100, 110, 125… There is no 95A standard size.

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How it works & the NEC rules behind it

Electrical systems are sized on diversity rather than total connected nameplate wattage. NEC 2026 Article 120 Part III (formerly Article 220) provides specific demand factor reduction tables for services and feeders.

Three Core NEC Demand Tables:

  • 1. General Lighting Demand (§120.42 / formerly §220.42):
    • Dwelling Units: First 3,000 VA @ 100%; 3,001 to 120,000 VA @ 35%; remainder @ 25%.
    • Hospitals: First 50,000 VA @ 40%; remainder @ 20%.
    • Hotels / Motels: First 20,000 VA @ 50%; next 80,000 VA @ 40%; remainder @ 30%.
    • Warehouses: First 12,500 VA @ 100%; remainder @ 50%.
  • 2. Electric Clothes Dryers (Table 120.54 / Table 220.54):
    • 1 to 4 dryers: 100% (min 5,000 VA per dryer)
    • 5 dryers: 85% | 10 dryers: 50% | 20 dryers: 35% | 30 dryers: 30%.
  • 3. Household Cooking Appliances (Table 120.55 / Table 220.55 Column C):
    • 1 Range: 8.0 kW (regardless of 8.75–12 kW rating)
    • 2 Ranges: 11.0 kW | 3 Ranges: 14.0 kW | 5 Ranges: 20.0 kW
    • 6 to 40 Ranges: 15 kW + (1 kW × Number of Ranges).

Formulas & equations

Dwelling Lighting Demand = Min(VA, 3000) + [Max(0, Min(VA, 120000) − 3000) × 0.35] + [Max(0, VA − 120000) × 0.25] Dryer Demand (VA) = Total Connected VA × Table 120.54 % Factor Cooking Range Demand (kW) = Table 120.55 Column C Lookup

NEC reference table

Occupancy / Load Type NEC 2026 Section Portion of Connected Load Demand Factor (%)
Dwelling Unit Lighting§120.42First 3,000 VA100%
Dwelling Unit Lighting§120.42From 3,001 to 120,000 VA35%
Dwelling Unit Lighting§120.42Remainder over 120,000 VA25%
Hospitals§120.42First 50,000 VA / Remainder40% / 20%
Dryers (5 units)Table 120.54Total connected nameplate85%
Dryers (10 units)Table 120.54Total connected nameplate50%
Cooking Ranges (1 unit)Table 120.55Single 12 kW range8.0 kW (66%)
Cooking Ranges (10 units)Table 120.55Ten 12 kW ranges (120 kW total)25.0 kW (20.8%)

Worked example, step by step

Example: Sizing Multi-Family Feeder for 12 Electric Cooking Ranges

Building: 12-unit apartment building, each unit has a 12 kW electric cooking range (144 kW total connected).

  • 1. Table 120.55 Column C Formula: For 6 to 40 ranges, demand is 15 kW + (1 kW × Number of Ranges).
  • 2. Calculation: 15 kW + (1 kW × 12) = 27.0 kW Demand.
  • 3. Diversified Amps @ 240V 1-Phase: 27,000 W ÷ 240V = 112.5 Amps (vs 600A non-diversified!).

Frequently asked questions

In the 2026 NEC reorganization, all Branch-Circuit, Feeder, and Service Load Calculations were renumbered from Article 220 to Article 120. Table 220.42 became Table 120.42, Table 220.54 became Table 120.54, and Table 220.55 became Table 120.55.

NO. Under NEC §120.42, office buildings, retail stores, and commercial occupancies must calculate general lighting at 100% demand with NO demand factor reduction, because all office lights operate continuously during business hours.

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