Engineering
Electrical Load Demand Calculator
Apply independent demand factors to lighting, receptacle, and motor groups. Compare connected and diversified kW by group, then calculate continuous-adjusted demand, planned capacity, and the overall demand factor.
Lighting diversified demand (kW)-
Receptacle diversified demand (kW)-
Motor diversified demand (kW)-
Total connected load (kW)-
Diversified demand before allowances (kW)-
Demand after continuous multiplier (kW)-
Capacity including spare allowance (kW)-
Decision view
Group demand dumbbells and capacity stack
Group demand dumbbells and capacity stackConnected and diversified group loads are compared before continuous and spare allowances build the final planning capacity.
Exact scenario comparisonMotor demand factor (%) changes while all other entered assumptions remain constant.
| Motor demand factor (%) | Lighting diversified demand (kW) | Receptacle diversified demand (kW) | Motor diversified demand (kW) | Total connected load (kW) | Diversified demand before allowances (kW) | Demand after continuous multiplier (kW) | Capacity including spare allowance (kW) |
|---|
How to use Electrical Load Demand Calculator
- Enter connected kW for each load group.
- Enter a demand factor for each group.
- Set the continuous multiplier and spare percentage.
- Compare group dumbbells and the final capacity stack.
Calculator guide
Understanding Electrical Load Demand Calculator
Connected load is the sum of nameplate loads; diversified demand estimates how much of each group operates coincidentally. This calculator keeps those concepts separate before applying continuous-load and spare-capacity allowances.
Calculation method
How the calculation works
Apply separate entered demand factors to three named load groups before adding continuous-load and spare-capacity allowances. Multiply each connected group by its demand factor, sum the diversified groups, apply the continuous multiplier, then add the selected spare-capacity percentage.
Detailed calculation process
Diversify each load group before adding design allowances
The defaults combine 45 kW lighting, 70 kW receptacles, and 120 kW motors with demand factors of 90%, 65%, and 80%.
General formula: D_i = L_i f_i; L_total = sum(L_i); D = sum(D_i); D_c = D m_c; C_plan = D_c(1+s); DF = D/L_total Demand factors apply to named groups before aggregation. The continuous multiplier and spare allowance are separate, sequential capacity adjustments rather than additional connected loads.
What each symbol means
Worked substitution with the default inputs
The defaults reduce 235 kW connected load to 182 kW diversified demand, then raise the planning basis to 227.5 kW continuous-adjusted and 273.0 kW with spare capacity.
Demand bridge
See diversity and allowances as different operations
A group comparison and capacity stack prevent double counting.
Worked situations
Practical examples
- Receptacle demand falls from 70 to 45.5 kW at 65%.
- The overall diversified demand factor is 77.447%.
- Allowances raise the planning capacity to 273 kW.
Better inputs
Useful tips
- Apply demand factors to the correct occupancy and equipment group.
- Keep continuous-load rules separate from diversity.
- Document whether spare is applied before or after other allowances.
Before relying on the result
Limitations and common mistakes
- Applicable factors and multipliers depend on jurisdiction and system purpose.
- Motor starting, phase balance, harmonics, emergency loads, and coincidence studies are excluded.
- The result is not a code-compliant feeder or transformer selection by itself.
Reference
Key terms
- Connected load
- Sum of installed or nameplate load.
- Diversified demand
- Modeled coincident operating load.
- Spare capacity
- Selected planning allowance above adjusted demand.
Important note
Calculated from the entered values using the displayed engineering relationship. Confirm design values, load cases, safety factors, standards, and field conditions with a qualified professional.
Frequently asked questions
Why not multiply the total by one demand factor?
Different load groups can have different operating patterns and entered factors.
Is spare capacity a demand factor?
No. It is an allowance added after the modeled demand.
Can planned capacity exceed connected load?
Yes, depending on continuous and spare multipliers.
Does this size conductors?
No. Electrical code, voltage, current, protection, and installation conditions remain separate.