18
102206
DETERMINING
ELECTRICAL
LOAD FOR
GENERATOR
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
5000 watts. Electric motors present a special problem when figuring load. Read
Step 3 carefully.
1. Make two lists of items you want powered 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. Remember, 1KW = 1000 watts.
Note:
The name-
plate 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 name-
plate states 3 amps at 120 volts. 3 amps x 120 volts = 360 watts.
3. Electric motors present a special problem. They require up to 3-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 5000 watts.
It is a good idea to have up to 25% extra capacity for future needs or extra equipment.
* – Always use starting watts, not running watts, when figuring correct electrical load.
x – Motors of higher horsepower are not generally used.
Approximate Starting Watts*
Motor
Approximate
Universal
Repulsion
Split
HP
Running
Motors
Induction
Capacitor
Phase
Rating
Watts
(small appliance)
Motors
Motors
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
x
x
Chart 2
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
Vacuum cleaner
600
750
Sump pump (1/3 hp)
700
2100
Refrigerator/freezer
800
2400
6" Circular saw
800
1000
Floodlight
1000
1000
Running Starting
Equipment
Watts
Watts
1/2" Drill
1000
1250
Toaster
1200
1200
Coffee maker
1200
1200
Skillet
1200
1200
14" Chain saw
1200
1500
Water well pump
(1/2 hp)
1000
3000
Hot plate/range
(per burner)
1500
1500
Water heater
5000
5000
Chart 1—Typical Electric Appliance Wattages
Chart to be used as reference. Data may vary with size, make, and/or model.
Summary of Contents for MGY5000C
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