Electrical Load Calculator for NYC Buildings
ANA›Life Services Authority›National Calculator Authority›Electrical Load Calculator for NYC Buildings
.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }
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).
Building Type
Residential (1-2 Family) Multifamily (3+ Units) Commercial / Retail
Total Conditioned Floor Area (sq ft)
Number of Dwelling Units
Number of Small Appliance Circuits (min 2)
Number of Laundry Circuits (min 1)
Electric Range Rating (kW, 0 if none)
Electric Dryer Rating (kW, 0 if none)
Air Conditioning Load (kW, 0 if none)
Electric Heat Load (kW, 0 if none)
Electric Water Heater (kW, 0 if none)
EV Charger Load (kW, 0 if none)
Service Voltage
120V (Single Phase) 240V (Single Phase) 208V (3-Phase) 480V (3-Phase)
Service Phase
Single Phase Three Phase
Total Floor Area (sq ft)
Occupancy Type
Offices (3.5 VA/sq ft) Banks (3.0 VA/sq ft) Auditoriums (3.0 VA/sq ft) Churches (2.0 VA/sq ft) Garages (1.0 VA/sq ft) Hospitals (2.0 VA/sq ft) Hotels/Motels (3.0 VA/sq ft) Industrial (3.0 VA/sq ft) Restaurants (3.0 VA/sq ft) Retail Stores (3.0 VA/sq ft) Warehouses (1.0 VA/sq ft)
HVAC Load (kW)
Largest Motor Load (kW, for 125% rule)
Other Fixed Loads (kW)
Service Voltage
120V 208V (3-Phase) 240V 277V 480V (3-Phase)
Service Phase
Single Phase Three Phase
Calculate
function eleToggleFields() { var type = document.getElementById('ele-bldg-type').value; document.getElementById('ele-res-fields').style.display = (type !== 'commercial') ? '' : 'none'; document.getElementById('ele-com-fields').style.display = (type === 'commercial') ? '' : 'none'; document.getElementById('ele-units-group').style.display = (type === 'multifamily') ? '' : 'none'; }
function eleVal(id) { return parseFloat(document.getElementById(id).value) || 0; }
function eleCalc() { var resultDiv = document.getElementById('ele-result'); var type = document.getElementById('ele-bldg-type').value; var html = '';
if (type === 'residential' || type === 'multifamily') { // ---- NEC Article 220 Standard Method for Dwellings ---- var sqft = eleVal('ele-floor-area'); var units = (type === 'multifamily') ? eleVal('ele-units') : 1; var smallAppl = eleVal('ele-small-appliance'); var laundry = eleVal('ele-laundry'); var rangeKw = eleVal('ele-range-kw'); var dryerKw = eleVal('ele-dryer-kw'); var acKw = eleVal('ele-ac-kw'); var heatKw = eleVal('ele-heat-kw'); var waterKw = eleVal('ele-water-heater-kw'); var evKw = eleVal('ele-ev-kw'); var voltage = eleVal('ele-voltage-res') || 240; var phase = eleVal('ele-phase-res') || 1;
if (sqft 0) { if (type === 'residential') { // Single range: use Column C of Table 220.55 if (rangeKw 0) { dryerVA = Math.max(dryerKw * 1000, 5000); if (type === 'multifamily') { // NEC Table 220.54 demand factors for multifamily var dryerFactor = 1.0; if (units '; html += 'Load ComponentVAkW'; html += 'General Lighting (3 VA/sq ft × ' + sqft + ' sq ft)' + lightingVA.toFixed(0) + '' + (lightingVA/1000).toFixed(2) + ''; html += 'Small Appliance Circuits (' + Math.max(smallAppl,2) + ' × 1,500 VA)' + smallApplVA.toFixed(0) + '' + (smallApplVA/1000).toFixed(2) + ''; html += 'Laundry Circuits (' + Math.max(laundry,1) + ' × 1,500 VA)' + laundryVA.toFixed(0) + '' + (laundryVA/1000).toFixed(2) + ''; html += 'Subtotal Before Demand Factor' + subtotal1.toFixed(0) + '' + (subtotal1/1000).toFixed(2) + ''; html += 'After NEC 220.42 Demand Factor' + demandVA.toFixed(0) + '' + (demandVA/1000).toFixed(2) + ''; if (rangeVA > 0) html += 'Electric Range (NEC Table 220.55)' + rangeVA.toFixed(0) + '' + (rangeVA/1000).toFixed(2) + ''; if (dryerVA > 0) html += 'Electric Dryer (NEC 220.54)' + dryerVA.toFixed(0) + '' + (dryerVA/1000).toFixed(2) + ''; if (hvacVA > 0) html += 'HVAC (Larger of AC/Heat — NEC 220.60)' + hvacVA.toFixed(0) + '' + (hvacVA/1000).toFixed(2) + ''; if (waterVA > 0) html += 'Water Heater' + waterVA.toFixed(0) + '' + (waterVA/1000).toFixed(2) + ''; if (evVA > 0) html += 'EV Charger (NEC 625.42)' + evVA.toFixed(0) + '' + (evVA/1000).toFixed(2) + ''; html += 'Total Calculated Load' + totalVA.toFixed(0) + ' VA' + totalKW + ' kW'; html += ''; html += ''; html += 'Calculated Current: ' + ampsRounded + ' A @ ' + voltage + 'V ' + (phase == 1 ? 'Single' : 'Three') + '-Phase
'; html += 'Minimum Service Size (NYC): ' + minService + ' Amperes
'; html += 'Note: NYC requires minimum 100A service per dwelling unit. 200A recommended for modern all-electric homes.
'; html += '';
} else { // ---- Commercial Load Calculation (NEC Article 220 Part IV) ---- var comArea = eleVal('ele-com-area'); var vaPerSqft = parseFloat(document.getElementById('ele-com-occupancy').value) || 3.5; var hvacKw = eleVal('ele-com-hvac-kw'); var motorKw = eleVal('ele-com-motor-kw'); var otherKw = eleVal('ele-com-other-kw'); var comVoltage = eleVal('ele-com-voltage') || 208; var comPhase = eleVal('ele-com-phase') || 3;
if (comArea '; html += 'Load ComponentVAkW'; html += 'General Lighting & Receptacles (' + vaPerSqft + ' VA/sq ft × ' + comArea + ' sq ft)' + comLightingVA.toFixed(0) + '' + (comLightingVA/1000).toFixed(2) + ''; html += 'After NEC Table 220.44 Demand Factor' + demandComVA.toFixed(0) + '' + (demandComVA/1000).toFixed(2) + ''; if (hvacVA > 0) html += 'HVAC Load (100%)' + hvacVA.toFixed(0) + '' + (hvacVA/1000).toFixed(2) + ''; if (motorVA > 0) html += 'Largest Motor (125% per NEC 430.24)' + motorVA.toFixed(0) + '' + (motorVA/1000).toFixed(2) + ''; if (otherVA > 0) html += 'Other Fixed Loads (100%)' + otherVA.toFixed(0) + '' + (otherVA/1000).toFixed(2) + ''; html += 'Total Calculated Load' + comTotalVA.toFixed(0) + ' VA' + comTotalKW + ' kW'; html += ''; html += ''; html += 'Calculated Current: ' + comAmpsRounded + ' A @ ' + comVoltage + 'V ' + (comPhase == 1 ? 'Single' : 'Three') + '-Phase
'; html += 'Minimum Service Size (NYC): ' + comMinService + ' Amperes
'; html += 'Note: NYC commercial buildings typically require 3-phase 208V or 480V service. Consult a licensed NYC Master Electrician for final design.
'; html += ''; }
resultDiv.innerHTML = html; }
#### 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)
- HVAC: Larger of AC or Heat load used (NEC 220.60 Non-Coincident Loads)
- EV Charger at 100% (NEC 625.42)
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)
#### 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
- NYC requires a minimum 100-ampere service for all dwelling units (NYC EC 230.79)
- 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
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