Thumb Rules-14 ( Quick Reference Demand-Diversity Factor)


 

Diversity Factor (NBC)

Type of Load

Type of Building

Individual House Hold , Individual Dwelling of a Block Small Shops, Stores, Offices & Business Premises Small Hotels, Boarding Houses, etc
Lighting 66% of  total current demand 90% of total current demand 75% of total current demand
Heating and power 100% of total current demand up to 10 A+ 50 % of any current  demand in excess of 10 A 100% of full load of largest Appliance + 75% of Remaining appliances 100% of full load of largest appliance+ 80% of second largest appliance + 60% of remaining appliances
Cooking appliances 10 A +30 percent full load of
connected cooking appliances in excess of 10 A + 6 A if socket-outlet incorporated in the unit
100 % of full load of largest appliance + 80% of full load of second largest appliance + 60% of full load of Remaining appliances 100 % of full load of largest appliance + 80 % of full load of second largest appliance + 60% of full load of Remaining appliances
Motors (other than lift motors which are subject to special consideration)   100% of full load of largest Motor + 80% of full load of second largest motor 100 % of full load of largest Motor + 50%of full load of remaining motors
Water heater (instantaneous) 100 % of full load of largest Appliance + 100%of full load of second largest appliance + 25 %of full load of remaining appliances 100 % of full load of largest Appliance + 100%of full load of second largest appliance + 25 %of full load of remaining appliances 100 % of full load of largest Appliance + 100%of full load of second largest appliance + 25 %of full load of remaining appliances
Water heater (thermostatically controlled) No diversity    
Standard arrangements of final circuits in accordance with good practice 100 percent of the current demand of the largest circuit + 40 percent of the current demand of every other circuit 100 percent of the current
demand of the largest circuit + 50 percent of the current demand of every other circuit
 
Socket outlets other than above and stationary equipment other than those listed above 100% of the current demand of the largest point + 40%of the current demand of every other point 100% of the current
demand of the largest point+ 75 % of the current demand of every other point
100%of the current demand of the largest point
+ 75%of the current demand of every point in main rooms (dining rooms, etc) + 40 % of the current demand of every other point
After calculating the electrical load on the above basis, an overall load factor of 70 to 90 percent is to be applied to arrive at the minimum capacity of substation.

 

Demand Factors (As Per Table 220.42  NEC)

Type of Occupancy Electrical Load Demand Factor
Dwelling units First 3000 VA 100%
From 3001 to 120,000 VA 35%
Remainder over 120,000V A 25%
Hospitals First 50,000 VA or less 40%
Remainder over 50,000 VA 20%
Hotels and motels, including apartment houses without provision for cooking by tenants First 20,000 VA 50%
20,001 VA to 100,000 VA 40%
Remainder over 100,000 VA 30%
Warehouses storage First 12,500 VA 100%
Remainder over 12,500 VA 50%
All others Total volt-ampere 100%

 

Non-dwelling Lighting Loads Demand Factors (As Per 220.44  NEC)

Type of Occupancy Electrical Load Demand Factor
Non-dwelling Receptacle Loads First 10KVA 100%
Remainder over 10KVA 50%

 

Diversity (The Electricians Guide 5th Edition by John Whitfield)

Type of final circuit Type of premises
Households Small shops, stores, offices Hotels, guest houses
Lighting 66% total demand 90% total demand 75% total demand
Heating and power 100% up to 10 A + 50% balance 100%X + 75%(Y+Z) 100%X + 80%Y + 60%Z
Cookers 10 A + 30% balance + 5 A for socket 100%X + 80%Y + 60%Z 100%X + 80%Y + 60%Z
Motors (but not lifts)   100%X + 80%Y + 60%Z 100%X + 50%(Y+Z)
Instantaneous water heaters 100%X + 100%Y + 25%Z 100%X + 100%Y + 25%Z 100%X + 100%Y + 25%Z
Thermostatic water heaters 100% 100% 100%
Floor warming installations 100% 100% 100%
Thermal storage heating 100% 100% 100%
Standard circuits 100%X + 40%(Y+Z) 100%X + 50%(Y+Z) 100%X + 50%(Y+Z)
Sockets and stationary equip. 100%X + 40%(Y+Z) 100%X + 75%(Y+Z) 100%X + 75%Y + 40%Z
X = the full load current of the largest appliance or circuit
Y = the full load current of the second largest appliance or circuit
Z = the full load current of the remaining appliances or circuits

 

Diversity factor for Building (Horizon Power)

No of customer Diversity factor
1 3
2 2.57
3 2.2
4 2
5 1.89
6 1.8
7 1.74
8 1.71
9 1.69
10 1.64
11 1.61
12 To 14 1.57
15 To 17 1.5
18 To 20 1.46
21 To 23 1.42
24 to 26 1.4
27 To 29 1.38
30 To 59 1.37
≥60 1

 

Demand Factor (The Electricians Guide Fifth Edition) by John Whitfield)

Area Demand Factor
Office / School 40%
Technical Blocks / Hospital 50%
Air Port / Banks / Department Store / Shopping Center / Public Place 60%
Restaurants / Factories (for 8 Hours Shifts) 70%
Workshops / Factories (for 24 Hours Shifts) 80%
Arc Furnace 90 % TO 100%
Arc Welding 20 % TO 50%
Compressor 20 % TO 50%
Conveyor Crane 90 % TO 100%
Had tool 20 % TO 40%
Paper Mills 50 % TO 70%
Induction Furnace 80 % TO 100%

 

Demand Factor As per No of Appliances

No of Appliances (A) Less than 3.5 KW (B) 3.5 KW to 8.5 KW (C) Less 12 KW
1 80% 80% 8%
2 75% 655 11%
3 70% 55% 14%
4 66% 50% 17%
5 62% 45% 20%
6 59% 43% 21%
7 56% 36% 22%
8 53% 35% 23%
9 51% 34% 24%
10 49% 32% 25%
11 47% 32% 26%
12 45% 32% 27%
13 43% 32% 28%
14 41% 32% 29%
15 40% 32% 30%
16 39% 28% 31%
17 38% 28% 32%
18 37% 28% 33%
19 36% 28% 34%
20 35% 28% 35%
21 34% 26% 36%
22 33% 26% 37%
23 325 26% 38%
24 31% 26% 39%
25 30% 26% 40%
26 To 30 30% 24% 15KW+1KW for Each
31 To 40 30% 22%
41 To 50 30% 20% 25KW+0.75KW for Each

 

51 To 60 30% 18%
More Than 60 30% 16%
       

 

Lighting Demand for Building (As per NBC)

Lighting demand for buildings should be considered as per type of building.
Where nothing is specified, for lighting demand of any type of building a maximum of 13 W/m2 of all built-up areas including balconies.
Covered parking areas may be considered at 3.23 W/m2 including balconies, service areas, corridors, etc, may be considered with very basic diversity of 80 % to 100 %.
Power requirements shall be considered at least 55 W/m2 with an overall diversity not exceeding 50 %. These shall be excluding defined loads such as  lifts,  plumbing  system,  fire  fighting  systems, ventilation requirement, etc.
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