Demand, Load and Diversity Factor Formulas

Maximum demand, demand factor, load factor and diversity factor formulas with a worked example and a table of maximum demand by demand factor.

The formulas

The connected load is the sum of the ratings of everything installed. The demand factor is at most 1, the load factor is at most 1 and the diversity factor is at least 1. Demand factors in practice come from your code or from measured data, so the values below are examples.

Worked example: a 500 kW connected load

The demand factor is 0.7. Over 30 days (720 h) the site used 168,000 kWh. The individual maximum demands of its feeders add up to 420 kW.

1. Pmd = 500 × 0.7 = 350 kW
2. Pavg = 168,000 / 720 = 233.3 kW
3. Load factor = 233.3 / 350 = 0.6667
4. Diversity factor = 420 / 350 = 1.2

Maximum demand for a 500 kW connected load

Frequently asked questions

Why is the maximum demand lower than the connected load?

Not every load runs at once or at full power. The demand factor allows for that, and it sizes the supply and the transformer.

What does a low load factor mean?

The average use is small against the peak, so the supply is sized for a peak that is rare. A tariff with a demand charge penalises that.

What is the difference between demand factor and diversity factor?

Demand factor compares the peak with the connected load. Diversity factor compares the sum of separate peaks with the peak of the group, because the peaks do not occur together.

Where do I get the demand factors?

Use the table in your wiring code or the guidance of the utility, or use measured data from similar sites.

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