Desa Determining Electrical Load for Generator, Typical Electric Appliance Wattages Chart

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PORTABLE GASOLINE GENERATORS

DETERMINING ELECTRICAL LOAD FOR GENERATOR

You must decide what electrical load your generator can power. Do this before us- ing generator. Use the following four-step method. It will help you select a load that is not too large. Make sure total wattage of all electrical loads does not exceed rated wattage of generator. For rated wattage of your generator, see Specifications, page 5. Electric motors present a special problem when figuring load. Read Step 3 carefully.

1.Make two lists of items you want pow- ered by generator. List all motors and motor powered appliances in one. List all lights, small appliances, etc. in the other. For standby service to home or building, only include items you must power.

2.Enter running watts of each item except motors. The light bulb or appliance nameplate lists its wattage. Remem- ber, 1KW = 1000 watts. Note: The nameplate may not list wattage. It may only list volts and amps. The formula for finding wattage is: Volts x Amps = Watts. For example: An appliance nameplate states 3 amps at 120 volts. 3 amps x 120 volts = 360 watts.

3.Electric motors present a special prob- lem. They require up to three-times their rated wattage to start. Chart 2, below, shows starting watts for different size motors. For example: an electric motor nameplate states 5 amps at 120 volts. 5 amps x 120 volts = 600 watts running. Multiply this figure by 3. This will show the starting watts needed. 600 watts x 3 = 1800 watts to start. When figuring the generator load for motors, you must use the starting watts figure.

Do not use the running watts figure. Note: Some motors require nearly the same wattage to run as to start. These items include saws, drills, hair dryers, and food mixers. See Chart 1 for typical appliance wattage examples.

4.Add watts and starting watts of all items. This total must not be larger than the rated wattage of your generator. It is a good idea to have up to 25% extra capacity for future needs or extra equipment.

Typical Electric Appliance Wattages

Chart 1

	Running	Starting
Equipment	Watts	Watts
Light bulb (100W)	100	100
Radio	150	150
Fan
	200	600
Television
	400	400
Furnace fan (1/3 hp)
	600	1800
with blower
Vacuum cleaner
	600	750
Sump pump (1/3 hp)
	700	2100
Refrigerator/freezer
	800	2400
6" Circular saw
	800	1000
Floodlight
	1000	1000
1/2" Drill
	1000	1250
Toaster
	1200	1200
Coffee maker
	1200	1200
Skillet
	1200	1200
14" Chain saw
	1200	1500
Water well pump
	1000	3000
(1/2 hp)
Hot plate/range
	1500	1500
(per burner)
10" Table saw
	2000	6000
Water heater
	5000	5000
(storage-type)

Chart 2

		Approximate Starting Watts*
Motor	Approximate	Universal	Repulsion		Split
HP	Running	Motors	Induction	Capacitor	Phase
Rating	Watts	(small appliance)	Motors	Motors	Motors
1/8	500	625	1100	1500	2250
1/4		875	1550	2100	3150
	700
1/3		1000	1750	2400	3600
	800
1/2		1375	2400	3300	4950
	1100
3/4		1750	3100	4200	x
	1400
1		2125	3750	5100	x
	1700
1 1/2		2625	4620	6300	x
	2100
2		3075	5400	7350	x
	2450
3		x	7900	10800	x
	3600

*– Always use starting watts, not running watts, when figuring correct electrical load. x – Motors of higher horsepower are not generally used.

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