What is a residential electrical load calculation?

A residential load calculation determines the total electrical demand of a dwelling and the minimum service size needed. NEC Article 220 Standard Method applies demand factors to general lighting, small appliance circuits, appliances, HVAC, and other loads to calculate the required ampacity at 240V.

What does NEC Article 220 say about service sizing?

NEC Article 220 requires a minimum of 3 VA per square foot for general lighting (Table 220.12), at least two 1,500 VA small appliance circuits, and one 1,500 VA laundry circuit. Demand factors from Tables 220.42, 220.54, and 220.55 reduce the total calculated load for service sizing.

How do I use this NEC residential load calculator?

Enter your dwelling's square footage, number of small appliance and laundry circuits, then add fixed appliances, ranges, dryers, HVAC, and heating loads using the + Add buttons. Click Calculate Service Size to get the total demand in VA, minimum service amps, and recommended panel size per NEC Article 220.

How are demand factors applied to general lighting loads?

NEC 220.42 applies tiered demand factors to the combined general lighting, small appliance, and laundry load: the first 3,000 VA at 100%, the next 117,000 VA at 35%, and amounts above 120,000 VA at 25%. This substantially reduces the calculated service size below the raw connected load.

What is the difference between 100A and 200A electrical service?

Homes with only basic loads may qualify for 100A service, but modern dwellings with electric ranges, dryers, HVAC, and EV chargers typically require 150A or 200A. Running this NEC Article 220 load calculation tells you exactly which service size is required and what panel to install.

How are ranges and dryers calculated under NEC Article 220?

Electric ranges are calculated using NEC Table 220.55 Column C demand schedule based on the number of units. Clothes dryers use NEC Table 220.54 — each unit is a minimum of 5 kW, with demand factors applied when 5 or more dryers are present.

Do I need a 200 amp service for a modern home?

For most single-family homes, 200A is the recommended standard. While NEC Article 220 may calculate less than 200A for smaller dwellings, practical load growth, EV charging, and local AHJ requirements typically make 200A the minimum recommended service size for new construction.

⚡ Electrical Calculator

NEC Residential Load Calculator

NEC Article 220 Standard Method — Dwelling service sizing with demand factors for lighting, appliances, HVAC & EV chargers

🏠 Dwelling Unit

Living Area (sq ft)

Finished living area only — NEC Table 220.12 (3 VA/ft²). Exclude garages, unfinished basements, open porches.

Small Appliance Circuits

Min. 2 required — NEC 210.11(C)(1). Each = 1,500 VA.

Laundry Circuits

Min. 1 required — NEC 210.11(C)(2). Each = 1,500 VA.

🔌 Fixed Appliances

QtykW Each

No appliances added — click + Add for dishwashers, water heaters, garbage disposals, etc.

NEC 220.53 — 75% demand factor applies when 4 or more fixed appliances total.

🍳 Cooking / Range Load

QtykW Each

No ranges added — click + Add for electric ranges or cooktops.

Calculated per NEC Table 220.55 Column C demand schedule.

🌀 Clothes Dryers

QtykW Each

No dryers added — click + Add for electric clothes dryers (min 5 kW each).

NEC Table 220.54 — minimum 5.0 kW per unit. Demand factors apply at 5+ units.

❄️ Air Conditioning / HVAC

QtykW Each

No A/C units added — click + Add for central A/C, mini-splits, heat pumps.

🔥 Electric Heating

QtykW Each

No heating added — click + Add for electric furnaces, baseboard heaters.

NEC 220.60 — non-coincident loads. Only the larger of total A/C or total heating is counted.

⚡ Other Specified Loads

QtykW Each

No other loads — click + Add for EV chargers, pool pumps, workshop panels, hot tubs, etc.

EV charger tip: enter nameplate kW × 1.25 for continuous load factor (NEC 210.19).

Please enter the living area in square feet to calculate.

NEC Article 220 — Residential Load Calculation Result

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Total Demand

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Min. Service

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Recommended Panel

NEC 220.42 / 220.52 / 220.53 / 220.54 / 220.55 / 220.60
General lighting demand: first 3,000 VA @ 100%, next 117,000 VA @ 35%, balance @ 25%. Non-coincident A/C vs. heating — larger used. Results at 240V single-phase service.

💡

Need NEC code lookup on the job site?

VoltageLab's AI Code Lookup has every NEC article explained in plain English — including Article 220 demand factors, service sizing, branch circuit rules, and more. Searchable from your phone in seconds. Used by journeymen, masters, and exam candidates across the USA.

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General lighting: 3 VA/ft² — NEC Table 220.12. Small appliance and laundry circuits: 1,500 VA each — NEC 220.52. Demand factors: first 3,000 VA @ 100%, next 117,000 VA @ 35%, balance @ 25% — NEC 220.42. Fixed appliances: 75% demand if 4+ units — NEC 220.53. Ranges: Column C demand — NEC Table 220.55. Dryers: 5 kW min/unit — NEC Table 220.54. HVAC: non-coincident loads — NEC 220.60. Total VA ÷ 240V = minimum service amps. Results are indicative — always verify with a licensed electrician before permit submission.

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NEC Residential Load Calculator

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