Diversity Factor

Diversity is the recognition that individual electrical loads within an installation do not all operate at their maximum rating at the same time. Consider a house with 10 kW of lighting, 12 kW of cooking, 20 kW of heating, and 10 kW of socket outlets — the total connected load is 52 kW, but the actual peak demand might be only 20 kW because the oven, all lights, and all heaters are never running simultaneously. Standards provide diversity allowances as multipliers or percentages: BS 7671 Table 1A suggests 66% for the first 10A of lighting, then 100% of the remainder; for cooking, 10A + 30% of the remainder + 5A if the socket outlet is on the same circuit. For large commercial installations, AS/NZS 3000 provides diversity tables based on building type. The after-diversity maximum demand (ADMD) concept applies to multi-unit developments — each additional dwelling adds a diminishing contribution to the total demand because the statistical probability of simultaneous peak use decreases with more units. Diversity factors are always less than or equal to 1.0.