Master Generators - Selection

Chosing The Correct Generator

Determining Electrical Load

You must decide what electrical load your generator can power. Do this before using 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 generator, see Specifications. Electric motors present a special problem when figuring load. Read Step 3 carefully.

Make two lists of items you want powered by generator. List all motors and motors 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.
Entering running watts of each item except motors. The light bulb or appliance nameplate list is wattage. Remember, 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 electrical name plate states 3 amps at 120 volts. 3 amps x 120 volts = 360 watts.
Electric motors present a special problem. They require up to three times their rated wattage to start. Chart 2 below shows starting wattage for different motors. For example: an electric motor nameplates 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 need. 600 watts x 3 = 1800 watts to start. When figuring the generator load for motors, you must use the starting 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 below for typical appliance wattage examples.
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 Wattage – CHART 1
Equipment	Running Watts	Starting Watts	Equipment	Running Watts	Starting Watts
Light Bulb (100W)	100	100	1/2" Drill	1000	1250
Radio	150	150	Toaster	1200	1200
Fan	200	600	Coffee Maker	1200	1200
Television	400	400	Skillet	1200	1200
Furnace Fan (1/3 hp) with blower	600	1800	14" Chain Saw	1200	1500
Sump Pump (1/3 hp)	700	2100	Water Well Pump (1/2 hp)	1000	3000
Refrigerator/Freezer	800	2400	Hot Plate/Range Per burner	1500	1500
6" Circular Saw	800	1000	10" Table Saw	2000	6000
Floodlight	1000	1000	Water Heater (Storage Type)	5000	5000
*Approximate Starting Watts - CHART 2**
Motor HP Rating	Approximate Running Watts	Universal Motors (Small Appliance)	Repulsion Induction Motors	Capacitor Motors	Split Phase Motors
1/8	275	400	600	850	1200
1/4	400	500	850	1050	1700
1/3	450	600	975	1350	1950
1/2	600	750	1300	1800	2600
3/4	850	1000	1900	2600	x
1	1000	1250	2300	3000	x
1 1/2	1600	1750	3200	4200	x
2	2000	2350	3900	5100	x
3	3000	x	5200	6800	x
* 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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