HOW MUCH POWER DO YOU NEED?
Generators produce AC voltage, very similar to the voltage available in your home, however while your electric utility company produces sufficient power for all your electric powered devices, a portable generator is limited in power output directly relational to the engine horsepower. The amount of power that a generator can produce is rated in watts. Rated power is generally 90% of maximum power as certain components lose efficiency as they are heated from use.

To determine wattage requirements you should determine which devices need to be powered simultaneously and what the starting requirement of the device is. A Wattage Calculator is provided to assist you. Remember that with simple "Power Management" techniques, a small generator can provide adequate power for home or recreational applications.

GENERATOR WATTAGE CALCULATOR
Depending on how you will use your generator, there are different categories to meet your needs. This can include recreation, home standby and construction. If you want a generator for home standby, for example, if you want to run your refrigerator, you'll need at least 3000 watts or more, and are REQUIRED to use a Transfer Switch so that power can go directly into your home.

Consider the maximum and rated power of the generator. This is important depending on what items you want to run off of your generator. Items such as toaster, lamps, and coffee makers are resistive, or constant loads and their total load can be calculated at amps x 1. Items such as saws and drills are reactive loads and while the running load may be small, the starting load should be calculated at running amps x 3. Remember, after the initial start less power is required for actual operation.

Always remember that simple power management will allow a smaller generator to do a big job. Very seldom are all tools or appliances operating simultaneously. When calculating power requirements, consider the starting requirements are only for the initial start and then additional tools may be operated in addition.

Remember Ohms Law from High School Physics?
Watts = Volts x Amps
Amps = Watts/Volts
So if you have two of the numbers (e.g. volts, amps) then you can find out the other (e.g. watts). This can help you to determine the rated power that you'll need from your generator.

AVERAGE WATTAGE REQUIREMENT GUIDE (AMPS X VOLTS = WATTS)
Household	Approximate Wattage Required For Starting	Approximate Running Wattage Requirements
Coffee Maker	600	600
Dishwasher Cool Dry	540	216
Electric Fry Pan	1500	1500
Electric Range 8-inch element	2100	2100
Microwave Oven 650 watts	1000	1000
Refrigerator or Freezer Energy Star	1200	132-192
Automatic Washer	1200	1200
Clothes Dryer Electric	6750	5400
Furnace Fan, gas or fuel oil
1/8 Horsepower	500	300
1/6 Horsepower	750	500
1/4 Horsepower	1000	600
1/3 Horsepower	1400	700
1/2 Horsepower	2350	875
Incandescent Lights	as indicated on bulb	as indicated on bulb
Radio	50 to 200	50 to 200
Sump Pump
1/3 Horsepower	1300	800
1/2 Horsepower	2150	1050
Television - Color	300	300
Air Conditioner 10,000 BTU	2200	1500
Contractor	Approximate Wattage Required For Starting	Approximate Running Wattage Requirements
Air Compressor 1 Horsepower	4500	1600
Bench Grinder 8 inches	2500	1400
Hand Drill 1/2 inch	900	600
High-pressure Washer 1 Horsepower	3600	1200
Circular Saw, Heavy Duty 71/4 inches	2300	1400
Electric Chain Saw 14 inches, 2 Horsepower	1100	1100
Table Saw 10 inches	4500	1800
Drills
3/8 inch 4 amps	600	440
1/2 inch 5.4 amps	900	600
Industrial Motors	Approximate Wattage Required For Starting	Approximate Running Wattage Requirements
Split Phase
1/4 Horsepower	1700	400
1/2 Horsepower	2600	600
Capacitor Start Induction Run
1/3 Horsepower	975	450
1 Horsepower	2300	1000
Capacitor Start Capacitor Run
1 1/2 Horsepower	4200	1600
Fan Duty
1/4 Horsepower	1200	650
Farm Equipment	Approximate Wattage Required For Starting	Approximate Running Wattage Requirements
Electric Fence, 25 miles	250	250
Milk Cooler	1800	1100
Milker (vacuum pump), 2 Horsepower	2300	1000
Portable Heater (kerosene, diesel fuel)
50,000 BTU	600	400
90,000 BTU	725	500
150,000 BTU	1000	625
Battery Charger
15 amp	380	380
60 amp with 250-amp boost	1500/5750	1500/5750
100 amp with 300-amp boost	2400/7800	2400/7800
Electric Welder
200 amp AC	9000	9000
230 amp AC, at 100 amp	7800	7800
Air Compressors	Approximate Wattage Required For Starting	Approximate Running Wattage Requirements
1/2 Horsepower	1600	975
1 Horsepower	4500	1600
Computers	Approximate Wattage Required For Starting	Approximate Running Wattage Requirements
Desktop	600 to 800	600 to 800
Laptop	200 to 250	200 to 250
Monitor (CRT)	200 to 250	200 to 250
Fax	600 to 800	600 to 800
Printer	400 to 600	400 to 600

"MAXIMUM" AND "RATED" POWER
A generator should never be operated at its MAXIMUM power output for more than 30 minutes. RATED power, or the power that a generator can produce for long periods of time, is a more reliable measure of generator power. Typically the rated power is 90% of the maximum power. For Example, a 2500 watt generator produces a maximum 2500 watts of power. This means at maximum power this generator could light up 25 100-watt light bulbs at the same time. The rated wattage of this generator would be 2300 watts and should only be used to power 23 - 100 watt light bulbs. When considering your power needs, first determine the highest power application such as a well pump for home power or air compressor for the job site. The power required to start the capacitor motor on these applications will determine the rated power of the generator you should choose for your application.

TYPES OF LOADS:
RESISTIVE LOADS = 1 x Power
The light bulb example is called a RESISTIVE type load and the power it requires is pretty easy to understand. Other resistive types of load are things like toasters, convection ovens, hot plates, curling irons, coffee makers, stereos and tv's. Resistive loads are usually appliances that do not have electric motors. Resistive Loads - Volts x Amps = Watts

The equation shows the relationship between watts, volts and amps in a purely resistive load. If you know any of the two variables, the third can be calculated. Example: You want a generator to power a 1000 watt flood light. The light is 120V and requires 1000 watts of power. Using the equation, we can calculate that the floodlight will draw 8.3 amps of electrical current. For reactive loads, the equation shows only a general relationship between watts, volts and amps. That's because the power requirements for reactive loads changes with operating conditions.

REACTIVE LOADS = 3 x Power
A REACTIVE load contains an electric motor. Some household appliances like a furnace or refrigerator have internal fans that come on intermittently, so extra wattage/power is needed to start the fan. Another example is power tools. An appliance or tool with a reactive load may require up to three times as much power (wattage) to start as it does to keep it running. Examples of reactive type loads:

• Refrigerators / freezers
• Furnace fans
• Well pumps
• Air conditioners
• Bench grinders
• Air compressors
• Power tools

When determining the proper generator for REACTIVE type loads, you must consider three modes of operation:

STARTING - The electric motor requires more power to start. The starting power required can be up to three (3) times the running amount.
RUNNING - The power required to run the electric motor once it has been started.
LOADED - When the electric motor begins to work (saw begins cutting wood, drill begins drilling thru a wall), its power requirement will increase. This is not applicable for most household appliances.

LOAD CODE:
Is a letter which represents the amps per horsepower (HP) to start the motor. Multiply the CODE (amps) times HP of motor to determine starting amps. For example: The data tag on our electric motor shows a code of L. Our motor is 1/3 HP. An L code is 84 amps per HP x 1/3 (motor HP) = 28 amps to start the motor.

CODE	AMPS PER HP TO START	CODE	AMPS PER HP TO START
A	26.0	L	83.3
B	29.5	M	93.3
C	33.3	N	104.0
D	37.4	P	116.6
E	41.6	R	133.3
F	46.6	S	133.3
G	52.4	T	166.6
H	59.0	U	186.6
J	66.6	V	more than 186.6

The law requires that customers with a permanently installed or portable generator do not connect it to another power source, such as Firelands Electric Cooperative's power lines. If you own and operate a generator, you are responsible for making sure that electricity from your unit cannot "back feed," or flow into Firelands' power lines. For safety's sake, be sure to use your generator correctly. If you do not, you risk damaging your property and endangering your life and the lives of Firelands' line workers who may be working on power lines some distance from your home.

Transfer Safety Switch

Home Generator Systems