Electrical Load Calculator for NYC Buildings

Estimates the minimum electrical service load for NYC residential and commercial buildings per NEC Article 220 and NYC Electrical Code (based on NYC Building Code Title 27 / Local Law 39).

Formulas Used

Residential (NEC Article 220 Standard Method):

  • General Lighting Load = Floor Area (sq ft) × 3 VA/sq ft (NEC Table 220.12)
  • Small Appliance Load = Number of Circuits × 1,500 VA (NEC 220.52(A), min 2 circuits)
  • Laundry Load = Number of Circuits × 1,500 VA (NEC 220.52(B), min 1 circuit)
  • Demand Factor: First 3,000 VA @ 100%; Next 3,001–120,000 VA @ 35%; Remainder @ 25% (NEC Table 220.42)
  • Range Demand per NEC Table 220.55 (Column C)
  • Dryer Demand per NEC 220.54 / Table 220.54
  • HVAC: Larger of AC or Heat load used (NEC 220.60 Non-Coincident Loads)
  • EV Charger at 100% (NEC 625.42)
  • Service Amps (1φ) = Total VA ÷ Voltage
  • Service Amps (3φ) = Total VA ÷ (Voltage × √3)

Commercial (NEC Article 220 Part IV):

  • Lighting Load = Floor Area × VA/sq ft per occupancy type (NEC Table 220.12)
  • Demand Factor: First 12,500 VA @ 100%; Remainder @ 50% (NEC Table 220.44)
  • Largest Motor × 125% added to total (NEC 430.24)
  • HVAC and other fixed loads at 100%

Assumptions & References

  • Based on NEC 2020 (NFPA 70) Articles 220, 430, and 625, as adopted by NYC
  • NYC Electrical Code is based on NEC with local amendments per NYC Building Code Title 27 / Local Law 39
  • Power factor assumed at 1.0 (unity) for VA calculations; actual PF may reduce kW demand
  • NYC requires a minimum 100-ampere service for all dwelling units (NYC EC 230.79)
  • 200A service strongly recommended for new construction and all-electric buildings per NYC LL97 electrification goals
  • Non-coincident loads (AC vs. Heat): only the larger load is counted per NEC 220.60
  • EV charger loads calculated at 100% continuous per NEC 625.42 and NYC EV-ready requirements
  • Multifamily demand factors per NEC Tables 220.42 and 220.54 applied to combined unit loads
  • Commercial occupancy VA/sq ft values from NEC Table 220.12
  • This calculator provides an estimate only. All electrical designs in NYC must be prepared and filed by a licensed NYC Master Electrician (ME) and may require PE/RA sign-off
  • Con Edison service entrance requirements and utility coordination not included

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