Table 3-1.—Types of Portable Generators Alternating  current Frequency Voltage 120/208 120 60-hertz 120/208 240/416 Phase 1 l & 3 3 Wires 2 4* 4 Fuel G D G D G D kW  Rating 5 X X X X 10 X X 15 X X 30 X X X 60 X 100 X X 200 X G—Gasoline driven. D—Diesel driven. *—Panel connections permit, at rated kW output: 120/208V 3-phase 4-wire, 120V 3-phase 3-wire, 120V single-phase 2-wire, 120/240V single-phase 3 wire. Before any part of the system can be designed, the amount of power to be transmitted, or the electrical load,  must  be  determined.  Electrical  loads  are  generally measured  in  terms  of  amperes.  kilowatts,  or kilovoltamperes.   In   general,   electrical   loads   are seldom constant for any appreciable time, but fluctuate constantly. In calculating the electrical load, you must determine the connected load first. The connected load is  the  sum  of  the  rated  capacities  of  all  electrical appliances, lamps, motors, and so on, connected to the wiring of the system. The maximum demand load is the greatest  value  of  all  connected  loads  that  are  in operation over a specified period of time. Knowledge of the maximum demand of groups of loads is of great importance: because it is the group maximum demand that determines the size of generators, conductors, and apparatus  throughout  the  electrical  system. The  ratio  between  the  actual  maximum  demand and  the  connected  load  is  called  the  DEMAND FACTOR. If a group of loads were all connected to the supply source and drew their rated loads at the same time, the demand factor would be 1.00. There are two main  reasons  why  the  demand  factor  is  usually  less than 1.00. First, all load devices are seldom in use at the same time and, even if they are, they will seldom reach maximum demand at the same time. Second, some load devices are usually slightly larger than the minimum size needed and normally draw less than their rated load. Since the maximum demand is one of the factors determining the size of conductors, it is important that the demand factor be established as closely  as  possible. 3-3