NEC Article 220 — Automated Load Calculation

NEC Belastingberekenings Werkblad

NEC Artikel 220 is de referentienorm voor het berekenen van elektrische service- en voedingslijnbelastingen.

NEC Table 220.12

Verlichtingsbelasting — NEC Tabel 220.12

NEC Tabel 220.12 geeft benuttingsfactoren in VA per vierkante meter.

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

NEC 220.42 vereist contactdoosbelasting te berekenen.

First 10,000 VA at 100% + remainder at 50%

Receptacle VA	Demand Factor	Demand VA
0 – 10,000 VA	100%	VA × 1.00
> 10,000 VA	50%	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

De grootste motorbelasting wordt berekend op 125% van zijn vollaststroom.

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)

NEC 210.19(A) beveelt max 3% spanningsval op vertakkingscircuits.

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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