Free Peak Demand calculator with clear step-by-step results.
Connected load is never all running at once. A demand factor reduces it to what each load actually draws, a diversity factor accounts for loads peaking at different times, and dividing by power factor converts real power into the apparent power that transformers, cables and tariffs are all sized on.
Maximum demand
kW = connected load x demand factor / diversity factor
Apparent power and current
kVA = kW / power factor; three-phase amps = kVA x 1000 / (V x root 3)
Maximum demand assessment for supply sizing must follow the applicable wiring regulations and utility connection rules. Have the design verified by a qualified electrical engineer.
Because network equipment must carry the apparent current, including the reactive component that does no useful work. Poor power factor raises kVA without raising kWh, which is why correction pays for itself.
It depends on load type - lighting can be near 100%, motor groups often 50-70%, and welding or intermittent plant far lower. Metered history is far better than a rule of thumb.