Maximum demand is the highest level of electrical power aggregate required by a facility over a short, defined interval—typically 15, 30, or 60 minutes. It is not simply the sum of the power ratings of all connected equipment, because not every appliance or machine operates simultaneously or at full capacity. Instead, maximum demand accounts for the reality of operational diversity. Why is Maximum Demand Calculation Essential? 1. Equipment Sizing

The sum of the power ratings (in Watts or Amps) of all electrical points in the building.

Maximum demand = 400 kW x 0.8 = 320 kW

Demand Factor=Maximum DemandTotal Connected LoadDemand Factor equals the fraction with numerator Maximum Demand and denominator Total Connected Load end-fraction A residential home with

Numerical example: 15‑min averages [120, 150, 200, 180] kW → MD = 200 kW. If PF = 0.9, MD_kVA = 200/0.9 ≈ 222.2 kVA.

Maximum demand calculation is not merely a formula to pass an exam; it is a direct lever for operational cost control and electrical reliability. Whether you are using the NEC diversity method for a new building, analyzing a month of SCADA data for a factory, or programming a demand controller to shed loads, the principles remain:

For each group, multiply connected load by its demand factor.

By mastering maximum demand calculation, you transform from a passive bill-payer to an active energy manager. The savings – often 20–40% on the demand portion of your bill – go straight to the bottom line.

Using standard tables and formulas provided by regulatory bodies. This is standard for new builds.

Electricians typically use standardized tables provided by regulatory bodies (like the NEC in the US or AS/NZS 3000) that dictate exactly what percentage of each load type must be included in the calculation. Real-World Example In a small home, the calculation might look like this:

This article provides an exhaustive look at maximum demand calculation—from fundamental formulas and regulatory standards (IEC, NEC, IS) to practical software-based load profiling and Power Factor (PF) correction.