Electrical Load Calculation: Step-by-Step Guide
Step-1: Connected Load: Sum of all power ratings
Step-2: Demand Factor: Not all loads run simultaneously
Step-3: Diversity Factor: Groups don’t run max at same time
Step-4: Maximum Demand: Connected Load × Demand Factor
Step-5: Current Calculation: Single Phase: I = P / (V x PF) Three Phase: I = P / (√3 x V x PF)
Step-6: Transformer Size: Transformer kVA = Total kW / PF + 25% margin
Step-7: Generator Size: Generator kVA = Total kW / (PF × 0.8)
Step-8: Cable Size: Cable current ≥ Load current x 1.25
Step-9: Breaker Selection: Breaker rating ≥ Load current x 1.25
Step-10: Voltage Drop Check: VD = 2 x L x I x R / 1000, Max 3% lighting, 5% power
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