A Maximum Demand Table is a structured record or calculation tool used in electrical engineering to determine the maximum power load an electrical installation draws from the supply over a specified period (typically 15, 30, or 60 minutes). It helps avoid overloading the supply transformer, cables, and switchgear.
| Load Type | Diversity Factor | |-----------|------------------| | Lighting (general) | 90% of total connected | | Socket outlets (general) | 50% of total connected | | Cooking appliances | 80% of total | | Water heaters (thermostatic) | 100% of largest + 50% of remaining | | Air conditioners (non-coincident) | 100% of largest + 40% of others | | Motors (non-continuous) | 100% of largest + 50% of next largest | | EV chargers | 100% (no diversity allowed often) | Multiply connected load by the diversity factor. Step 4: Sum Demands Add the individual demands to get total maximum demand (in kW or kVA). For mixed single & three-phase loads, convert to a common base (e.g., kVA). Step 5: Compare with Supply Capacity Ensure MD ≤ supply transformer/fuse rating. If MD exceeds 80% of supply rating, consider load shedding or upgrading supply. Example Table (Small Office) | Circuit / Load | Connected (kW) | Diversity Factor | Demand (kW) | |----------------|----------------|------------------|--------------| | Lighting (LED) | 3.0 | 0.9 | 2.70 | | 13A Sockets (10 outlets) | 13.0 | 0.5 | 6.50 | | Air Conditioning (2 units) – largest | 2.5 | 1.0 | 2.50 | | Air Conditioning (2 units) – second | 2.5 | 0.5 | 1.25 | | Water Cooler | 0.5 | 1.0 | 0.50 | | Photocopier (standby + print) | 1.2 | 0.8 | 0.96 | | Total Maximum Demand | 22.7 kW | – | 14.41 kW | maximum demand table