Maximum Demand - Calculation

Digital controls can interlock high-power appliances (e.g., preventing a water heater from running while an EV is fast-charging), artificially lowering the actual maximum demand of a facility. 7. Conclusion

For HVAC (often 40-60% of MD), make ice or chill water at night. Use that stored cooling during daytime peak hours. The chiller compressor runs at night (off-peak), reducing daytime MD by hundreds of kW.

Calculating Maximum Demand (MD) is essential for sizing electrical components like cables and circuit breakers without over-engineering the system. It represents the highest expected peak load, rather than just the sum of all connected equipment. Core Calculation Methods Electrical standards like AS/NZS 3000 (Australia/NZ) BS 7671 (UK) define four primary ways to determine MD: Calculation (Using Diversity Factors): maximum demand calculation

15,000 VA×1.0=15,000 VA15 comma 000 VA cross 1.0 equals 15 comma 000 VA

Example: For domestic lighting, you might apply a diversity factor of . This means you assume only two-thirds of the lights will be on at once during peak times. Digital controls can interlock high-power appliances (e

When designing distribution boards, the maximum demand is rarely the sum of all branch circuits.

This is the standard for design-stage calculations when no real load data exists. Use that stored cooling during daytime peak hours

Transformer size: 36.4 / 0.9 PF = 40.4 kVA → 50 kVA.

Calculated Group Demand=Connected Group Load×Demand FactorCalculated Group Demand equals Connected Group Load cross Demand Factor Step 5: Sum and Apply System Diversity