[ MD = (Load_1 \times DF_1) + (Load_2 \times DF_2) + ... + (Load_n \times DF_n) ]
In the world of electrical engineering and facility management, Maximum Demand (MD) is a critical metric. It isn't just about keeping the lights on; it directly impacts your capital expenditure (cable/transformer sizing) and operational expenditure (electricity bills).
Disclaimer: This guide provides estimation methods. Always consult a licensed electrical engineer for final design and safety compliance.
Where is the Demand Factor (or Diversity Factor). Standard Demand Factors (Reference Guide) | Load Type | Typical Demand Factor | Notes | | :--- | :--- | :--- | | Lighting (Office) | 0.75 – 0.90 | Fluorescent/LED | | Lighting (Warehouse) | 0.95 – 1.00 | High bay, always on | | General Power Outlets | 0.10 – 0.50 | Varies heavily by occupancy | | HVAC (Cooling) | 1.00 | Worst-case summer day | | HVAC (Heating) | 0.80 – 1.00 | Electric heat is high demand | | Lifts / Elevators | 0.40 – 0.60 | Largest motor only | | Motors (Continuous) | 1.00 | Pumps, compressors | | Motors (Intermittent) | 0.40 – 0.60 | Conveyors, cranes | | Kitchen Equipment | 0.40 – 0.70 | Not all used at once | The "Pro" Calculator Tool (Manual Method) If you don't have a power analyzer, use this systematic approach to estimate your MD.
Why average? A motor starting up might draw 600A for 2 seconds, but that doesn't melt the cables. The 15-minute average is what heats the transformer. Why does it matter? Utilities size their transformers for your MD. If you have a 5-minute spike once a month, you are paying for infrastructure you use 0.01% of the time. You cannot simply add up the nameplate ratings of all breakers. That is Connected Load , not Maximum Demand. Diversity saves you.
In most commercial tariffs, the electricity bill is split into two parts: and Demand Charges (kVA/kW) . The Demand Charge is often the larger shock—it is based on the highest average load recorded during a billing window.
To take control of this, you need a . What is Maximum Demand? Maximum Demand is the highest average load (usually measured over 15, 30, or 60-minute intervals) that a system draws during a billing period.
Apply the factors from the table above.