How to Calculate Electrical Load for a House NEC Article 220 Guide 2026
An electrical load calculation per NEC Article 220 determines the minimum service size (100A, 200A, or 400A) your home needs. The calculation adds up general lighting (3 VA per sq ft), small appliance circuits (3,000 VA), laundry (1,500 VA), then applies demand factors. Major loads like AC, range, dryer, water heater, and EV charger are added at their nameplate or NEC demand factor ratings.
Step 1: General Lighting and Receptacles
NEC 220.12 assigns 3 VA per square foot of living space for general lighting and receptacle loads. For a 2,000 sq ft home: 2,000 × 3 = 6,000 VA. This covers all general-purpose receptacles and lighting outlets. Garages, unfinished basements, and attics with outlets are included in the square footage. Note: this is a calculation value, not actual usage — demand factors applied later reduce the effective load significantly.
Step 2: Small Appliance and Laundry Circuits
NEC 220.52(A) requires a minimum of two 20A small appliance circuits for the kitchen, pantry, dining room, and similar areas. Each is calculated at 1,500 VA = 3,000 VA total. NEC 220.52(B) requires at least one 20A laundry circuit calculated at 1,500 VA. Add these to the general lighting: 6,000 + 3,000 + 1,500 = 10,500 VA before demand factors.
Step 3: Apply Demand Factors
NEC Table 220.42 provides demand factors for the combined general lighting, small appliance, and laundry loads: First 10,000 VA at 100% = 10,000 VA. Remainder at 40% = (10,500 - 10,000) × 0.40 = 200 VA. Subtotal after demand: 10,200 VA. These demand factors reflect the reality that not all lights and receptacles are used simultaneously — a huge reduction from the calculated load.
Step 4: Add Major Appliances
Add each major appliance at its nameplate rating or NEC demand factor: Central AC (5 ton): 6,000W at 100%. Electric Range (12 kW): 8,000W per NEC Table 220.55 (demand factor). Electric Dryer: 5,000W at 100% (or NEC 220.54 demand for multiple). Water Heater: 4,500W at 100%. EV Charger (48A): 11,520W at 100%. Dishwasher: 1,500W at 100%. Total major loads: approximately 36,520W. Note: NEC 220.60 says use the larger of AC or heat — not both.
| Load | VA/Watts | Demand Factor | Demand Load |
|---|---|---|---|
| General Lighting (2000 sf) | 6,000 VA | See below | — |
| Small Appliance (2 ckts) | 3,000 VA | See below | — |
| Laundry (1 ckt) | 1,500 VA | See below | — |
| Subtotal | 10,500 VA | First 10k: 100% | 10,200 VA |
| Central AC | 6,000W | 100% | 6,000W |
| Electric Range | 12,000W | NEC 220.55 | 8,000W |
| Water Heater | 4,500W | 100% | 4,500W |
| Dryer | 5,000W | 100% | 5,000W |
| EV Charger | 11,520W | 100% | 11,520W |
| TOTAL | — | — | 45,220W = 189A |
Step 5: Calculate Service Size
Total calculated load: 10,200 VA (Step 3) + 36,520 VA (Step 4) = 46,720 VA. Convert to amps at 240V: 46,720 ÷ 240 = 195A. This home needs a 200A service. Without the EV charger, the load would be 35,200 VA ÷ 240 = 147A — still requiring 200A but with more headroom. A home with gas heat, gas cooking, and no EV might calculate under 100A and be fine with 100A service. Use our Electrical Load Calculator for exact NEC calculations.
Disclaimer: For educational reference only. Consult a licensed professional.