NEC 220.82 Optional Method5,000 Sq Ft • Luxury Custom EstateCode Compliant
400 Amp Service Load Calculation for 5,000 Sq Ft Luxury Home
Complete electrical demand load breakdown following NEC Article 220.82. Formally verified for electrical permit submissions, service disconnect sizing, and utility service drop requirements.
Calculated Demand342.7 Amps@ 240V Single Phase
Recommended Panel400 AmpsNEC Standard Rating
Service Feeder (Al)Dual ParallelTable 310.12 (75°C)
Minimum ConduitDualEMT / PVC Sch 40
Connected Appliance Profile & Nameplate Loads
Specific mechanical equipment ratings evaluated for this residential dwelling unit
Cooking EquipmentCommercial Range, Warming Drawers, Steam Oven (22,000 VA)
Clothes DryerDual Electric Dryers (10,000 VA)
Water HeatingCommercial-Grade Heat Pump + Storage System (8,000 VA)
HVAC Primary Heating/CoolingThree Heat Pump Zones: 3-Ton, 3-Ton, 2.5-Ton (16,000 VA total)
Electric Vehicle Supply (EVSE)Dual 48A EV Chargers (23,040 VA continuous)
Auxiliary Fixed AppliancesHeated Pool & Spa (16,000 VA), Snow Melt System / Detached Garage (10,000 VA), Dual Dishwashers (3,000 VA)
NEC 220.82 Step-by-Step Demand Worksheet
Official calculation table matching municipal electrical permit application format
| Calculation Step • NEC Section | Connected VA | Demand Factor | Demand VA |
|---|---|---|---|
| General Lighting & Receptacles3 VA/sq ft • NEC 220.82(B)(1) | 15,000 VA | Subtotal Group | — |
| Small Appliance Circuits2 Circuits @ 1,500 VA • NEC 220.82(B)(2) | 6,000 VA | Subtotal Group | — |
| Laundry Branch Circuit1 Circuit @ 1,500 VA • NEC 220.82(B)(2) | 3,000 VA | Subtotal Group | — |
| Fixed & Fastened-in-Place AppliancesRange, Dryer, WH, DW, Disposal • 220.82(B)(3) | 69,000 VA | Subtotal Group | — |
| General Connected Load Subtotal | 93,000 VA | — | — |
| • First 10,000 VA of General Load | 10,000 VA | 100% | 10,000 VA |
| • Remainder above 10,000 VA | 83,000 VA | 40% | 33,200 VA |
| General Demand Load Subtotal | — | 220.82(B) | 43,200 VA |
| Heating & Air Conditioning (HVAC)Largest Non-Coincident Load • NEC 220.82(C) | 16,000 VA | 100% | 16,000 VA |
| Electric Vehicle Charger (EVSE)Continuous Load • NEC 625.42 | 23,040 VA | 100% / 125% | 23,040 VA |
| TOTAL CALCULATED DEMAND LOAD | — | Total / 240V | 82,240 VA • 342.7 A |
Service Conductor & Grounding Sizing Schedules
Minimum wire gauges and raceway sizes compliant with NEC Table 310.12 and Table 250.66
Service Entrance Conductors
Copper Conductor (THHN/XHHW):Dual Parallel Sets of 3/0 AWG Copper THHN
Aluminum Conductor (XHHW-2):Dual Parallel Sets of 250 kcmil Aluminum XHHW-2
Minimum Raceway / Conduit:Dual 2-1/2" Conduit Runs
Temperature Rating:75°C Terminations
Grounding & Bonding Electrode System
GEC to Water Pipe / Intersystem:1/0 AWG Bare Copper
Ground Rod System:Dual 5/8" × 8ft Rods (6ft Spaced)
GEC to Ground Rods (Max):#6 AWG Copper
Main Bonding Jumper:Installed at Main Disconnect Only
Master Electrician Inspection & Installation Notes
- Calculated demand is 342.7A, utilizing 85.7% of a 400A service rating.
- Electrician specification: Two 200A main service panels, each fed with 250 kcmil aluminum or 3/0 copper conductors.
- CT (Current Transformer) metering may be mandated by certain municipal utility providers for residential services exceeding 320A continuous.
Frequently Asked Code Questions
When is CT metering required for 400 amp residential services?
Many electric utility providers require CT (Current Transformer) metering cabinets once continuous calculated load exceeds 320A or when using a single 400A panel rather than dual 200A panels.