Applying PEC Demand Factors to Lighting, Receptacle, and Appliance Loads
Demand factors capture the reality that not every load runs at once. Applied correctly they shrink the service size — and the cost — without compromising safety.
Connected load first
Build the connected load from the plans: general lighting at the code VA-per-square-metre figure for the occupancy, small-appliance and laundry circuits at their fixed allowances, then each fixed appliance and motor at its nameplate rating.
The demand-factor tables
| Load category | Demand factor |
|---|---|
| General lighting — first 3 kVA | 100% |
| General lighting — 3 kVA to 120 kVA | 35% |
| Small-appliance & laundry circuits | included with lighting above |
| Fixed appliances, 4 or more | 75% |
| Electric range (single, ≤12 kW) | 8 kW demand |
| Largest motor | 125% |
Percentages follow common PEC residential practice; commercial occupancies use their own tables.
Worked residential example
House: 180 m² general lighting at 24 VA/m² = 4320 VA; two small-appliance circuits + laundry = 4500 VA; fixed appliances (water heater 4500, dishwasher 1200, exhaust 300, disposer 600) = 6600 VA; range 10 kW; aircon (largest motor) 3500 VA.
First 3000 @ 100% = 3000
Remaining 5820 @ 35% = 2037
Fixed appliances 6600 @ 75% = 4950
Range = 8000 (table demand)
Aircon 3500 @ 125% = 4375
Total demand = 22 362 VA
The connected load was over 30 kVA; the demand load justifies a 100 A service instead of 150 A.
EngEst Pro applies the correct demand factor to every load category as you enter it — the running total shows connected load and demand load side by side, and the service and main breaker size update live.
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