The NEC Optional Method, defined in NEC 220.82, provides a streamlined and realistic approach for calculating residential electrical loads. When applied correctly, it reflects modern residential usage patterns and often results in a lower calculated demand than the Standard Method—while remaining fully compliant with the National Electrical Code.

This method is widely used for one-family dwelling units and individual dwelling units in multifamily buildings, provided the conditions of applicability are met and accepted by the Authority Having Jurisdiction (AHJ).

Below is a step-by-step breakdown of the Optional Method exactly as it is applied in practice, aligned with NEC 2023.

Per NEC 220.82(A) this method applies to a dwelling unit where the total connected load is supplied by a single set of service or feeder conductors having an ampacity of 100 amperes or greater.

The supply system must be one of the following:

• 120/240-volt, 3-wire, single-phase, or
• 208Y/120-volt, 3-wire system

When these conditions are satisfied, the Optional Method may be used to determine the minimum required service or feeder size, subject to AHJ approval.

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STEP 1 — General Lighting, Small-Appliance & Laundry Loads
NEC 220.82(B)(1)

Begin by calculating and combining the following lighting-related loads:

• General lighting load at 3 VA per square foot
  • Two required small-appliance circuits at 1,500 VA each
  • One required laundry circuit at 1,500 VA

STEP 2 — Fastened-in-Place Appliances
NEC 220.82(B)(2)

Add all fixed (fastened-in-place) appliances at 100% of nameplate rating, including but not limited to:

• Dishwashers
  • Garbage disposals
  • Water heaters
  • Built-in microwaves
  • Trash compactors

STEP 3 — Cooking Equipment
NEC 220.82(B)(3)

Add cooking equipment at 100% of nameplate rating, including:

• Electric ranges
  • Wall ovens
  • Cooktops

Under the Optional Method Table 220.55 is not used

STEP 4 — Electric Clothes Dryer
NEC 220.82(B)(4)

Add the electric clothes dryer load at 100% of the nameplate rating.

Under the Optional Method Table 220.54 is not used

STEP 5 — Apply Optional Method Demand Factor
NEC 220.82(B)

After Steps 1 through 4 are added together, apply the Optional Method demand factor to the combined load:

• 100% of the first 10,000 VA
  • 40% of the remaining load

⚠️ Important:
This demand factor is applied after lighting, small-appliance, laundry, fixed appliance, cooking, and dryer loads are combined.

STEP 6 — HVAC Loads (Noncoincident)
NEC 220.82(C)

Heating and cooling loads are treated as noncoincident loads.

Rules:
• Include only the larger of the heating or cooling load
• Added at 100% of nameplate rating
• Motor demand factors in NEC 220.50 do not apply

STEP 7 — Electric Vehicle (EV) Charger Loads
NEC 625.41

Electric vehicle chargers are treated as continuous loads and are added after the Optional Method demand calculation.

Rule:
• EV charging load = 125% of the rated load

STEP 8 — Final Total Load (Service & Feeder Size)

Add the HVAC and EV loads to the demand-reduced total to determine the final calculated dwelling unit load.

This value establishes:
• Required service size (100A, 200A, 400A, etc.)
• Feeder sizing
• Utility and transformer coordination

The NEC Optional Method Calculator

Zigtech provides an easy-to-use NEC Optional Method load calculator, designed to follow NEC 2023 requirements step by step.

Try the Optional Method Load Calculator here:
https://zigtech.ai/single-family/