NEC Article 220 — Automated Load Calculation

NEC Load Calculation Worksheet

NEC Article 220 is the reference standard for calculating electrical service and feeder loads. FrameAI automates the whole workflow — from your panel schedule Excel to a complete load calculation worksheet covering all demand categories required by AHJs.

NEC Table 220.12

Lighting Load — NEC Table 220.12

NEC Table 220.12 gives demand factors in VA per square foot for different building area ranges. FrameAI applies the correct VA/sqft for your building square footage and generates a per-panel lighting demand figure.

Demand VA = Building sqft × VA/sqft (from Table 220.12)
Example — 8,000 sqft Office
Building area 8,000 sqft
VA/sqft (Table 220.12) 3.0 VA/sqft
Gross lighting VA 24,000 VA
Demand factor 100%
Lighting demand 24,000 VA
NEC 220.42

Receptacle Load — NEC 220.42

NEC 220.42 requires receptacle loads to be computed at 180 VA per strap (single-phase) or per yoke. FrameAI applies the two-tier demand factors: first 10,000 VA at 100%, remainder at 50% (for non-dwelling occupancies).

First 10,000 VA at 100% + remainder at 50%
Receptacle VADemand FactorDemand VA
0 – 10,000 VA100%VA × 1.00
> 10,000 VA50%10,000 + (VA−10,000) × 0.50
Example — 36,000 VA receptacles
First 10,000 VA 10,000 VA × 1.0 = 10,000 VA
Remaining 26,000 VA 26,000 VA × 0.5 = 13,000 VA
Receptacle demand 23,000 VA
NEC 430.24

Motor Load — NEC 430.24

The largest motor load is computed at 125% of its full-load current. Additional motors are computed at 100%. FrameAI identifies the largest motor per panel and applies the correct multiplier.

Largest motor: VA × 1.25  |  Other motors: VA × 1.00
Example — MDB with 3 motors
Largest (elevator): 7,500 W / 0.75 PF 10,000 VA × 1.25 = 12,500 VA
HVAC motor: 12,000 W / 0.80 PF 15,000 VA × 1.00 = 15,000 VA
Pump motor: 3,700 W / 0.80 PF 4,625 VA × 1.00 = 4,625 VA
Motor demand total 32,125 VA
NEC Chapter 9 · 210.19(A)

Voltage Drop — NEC Chapter 9

NEC 210.19(A) Informational Note No. 4 recommends a maximum of 3% voltage drop on branch circuits and 5% total from service to furthest point. FrameAI calculates drop per circuit from watts, length, voltage, and conductor size.

VD% = (k × I × L × 2) ÷ (V × kcmil × div) k = 12.9 (Cu) | 21.2 (Al)   div = 1 (3φ) or 2 (1φ)
Example — 22m, #12Cu, 230V, 18.3A
Current 18.3 A
Length (one-way) 22 m
#12 AWG kcmil 6.53 kcmil
Voltage drop (1φ) (12.9 × 18.3 × 22 × 2) ÷ (230 × 6.53)
Voltage drop 4.8 V = 2.1%
Pass / 3% limit? ✓ Pass
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