01 General Load Diversity
NEC 220.82(B) applies a two-stage demand factor to general lighting, small appliances, and laundry circuits.
| Load Portion (VA) | Demand Factor | Calculation Method |
|---|---|---|
| First 10,000 VA | 100% | Add at full nameplate rating. |
| Balance over 10,000 VA | 40% | Multiply remainder by 0.40. |
Total Load = 10,000 + ((General Loads - 10,000) × 0.40)
Need the mandatory circuit counts used in this math?
NEC 210.11(C) Required Circuits
02 The Rule of Four
Fixed appliances such as dishwashers, water heaters, and disposal units qualify for a secondary diversity factor when grouped.
75% Demand Factor
Applies only if 4 or more fixed appliances are present on the same service.
03 The HVAC Winner Rule
Per NEC 220.60, you do not sum heating and cooling loads. Only the largest load is calculated, as they cannot operate simultaneously.
| Equipment Type | Demand Factor | NEC Reference |
|---|---|---|
| Central Air Conditioning | 100% | 220.82(C)(1) |
| Heat Pump (Compressor + Supp.) | 100% | 220.82(C)(3) |
| Electric Space Heating (3+ units) | 65% | 220.82(C)(5) |
Crucial Calculation Note
If using the Optional Method, the HVAC load is added at 100% of its nameplate value (unless applying the 65% multi-unit heater rule) AFTER the 40% diversity factor is applied to the general loads.
04 Continuous Loads & EVSE
Electric Vehicle Supply Equipment (EVSE) is a continuous load. It does not receive a diversity "discount" and requires a safety buffer.
125% Multiplier
EV Chargers must be calculated at 1.25x the circuit rating to prevent breaker nuisance tripping during long charging cycles.
Summary of Factors
| Load Category | Optional Method (220.82) | Standard Method (220.40) |
|---|---|---|
| General Lighting | 100% of first 10kVA, then 40% | 100% of first 3kVA, then 35% |
| Fixed Appliances | Included in 40% General | 75% (if 4+ units) |
| Dryer / Range | Nameplate (in 40% Pool) | Table 220.54 / 220.55 |
| HVAC | Largest (Heat vs Cool) @ 100% | Total Summed @ 100% |
Apply These Factors Now
Use our multi-year engine to calculate your total demand using these exact standards.