Americas Generators
(800)434-0003(305)592-6800

FAQ

What type of fuel is best?
What size generator do I need?
How do I convert AMPS to kW or KVA?
How do I apply generator sets to motor loads?


Q: What type of fuel is best?

A: There are many advantages and disadvantages to different types of fuel. Nearly all Generators use either gasoline, diesel, natural gas or propane. The following information will hopefully answer any questions or concerns you may have concerning different fuel sources.

Gasoline:

  • Advantages:
    • Common fuel source - easily obtained
    • Increases portability of smaller generators
  • Disadvantages:
    • Highly flammable
    • Short shelf life (approximately 12 months)
    • Storing large quantities is hazardous
    • May not be available during power outages
    • Somewhat Expensive ($1.50 to $2.00 per Gallon)
    • Inefficient

Propane:

  • Advantages:
    • Long shelf life
    • Clean burning
    • Easily stored in both large tanks or in smaller 5 - 10 gallon cylinders
    • Obtainable during power outages - gas stations may be unable to pump fuel during an area wide outage
  • Disadvantages:
    • Pressurized cylinder of flammable gas
    • Fuel system is more complicated (increased possibility of failure)
    • Larger tanks are not aesthetically pleasing (unsightly)
    • Fuel system plumbing results in higher installation cost
    • Somewhat Expensive ($1.60 to $1.80 a gallon)

Natural Gas:

  • Advantages:
    • Unlimited fuel source - refueling not necessary
    • Clean burning
    • Available during power outages
  • Disadvantages:
    • May be unavailable during natural disasters (earthquakes, etc)
    • Lower power output (30% less BTU's per unit than gasoline)
    • Fuel system plumbing results in higher installation cost
    • Not available in many areas

Diesel:

  • Advantages:
    • Least flammable fuel source
    • Easily obtained
    • On site fuel delivery available
  • Disadvantages:
    • 18-24 month shelf life
    • Installing large storage tanks raises cost of system
    • May not be available during power outages

Back to top


Q: What size generator do I need?

A: Power requirements must be determined to properly size your generator. We are providing some steps to assist you in approximating the size generator for your power needs. Please keep in mind that unless you are qualified, you should use a certified electrician to determine your power needs. At Americas Generators it is our goal to assist our customers in any way possible. If you have any questions, please do not hesitate to contact us.

Steps to Determine Generator Requirements

  1. Determine your need. Do you want the generator to operate part or all of your home or office?
  2. Identify the appliances and/or tools the generator will need to power. The "Common Wattage Guide" below will help you determine your need.
  3. Determine the wattage for each appliance and tool you plan to use frequently.
  4. Identify motor and pump requirements. Use the motor and pump charts provided below.
  5. Calculate and total the wattage for the motors and pumps frequently used. Always use starting watts, not running watts, when determining the correct electrical load requirements.
  6. Total the wattage of the appliances & tools and the motors & pumps. Keep in mind that if you coordinate your power usage wisely you do not have to operate everything all at once. Therefore, for emergency use you don’t necessarily need to size the generator to operate everything simultaneously.
  7. Convert watts into kilowatts by dividing the watts in step VI. to determine the generator size required. Please note that it is suggested, although not absolutely necessary, to size the generator 20-25% over the size you determine your needs to be. This will allow room for future growth. For example, if you determine that you will need a 15 kW generator then it is advisable to purchase an 18 kW generator to accommodate future expansion.

Common Wattage Guide

ItemRunning WattsStarting Surge
100 watt light bulb100100
Radio AM/ FM stereo50-20050-200
Radio CB5050
Fan200200
Television300-400300-400
Microwave oven7001000
Air conditioner32505000
Furnace fan (1/3 HP blower)6001800
Vacuum cleaner600750
Sump pump (1/3 HP)7002100
Refrigerator/ Freezer8002400
Freezer5001500
6" circular saw8001000
Floodlight10001000
1/2" electric drill10001250
Toaster12001200
Coffee maker12001200
Electric skillet12001200
14" electric chain saw12001500
1/2 HP water well pump10003000
Hot plate15001500
Electric range1000010000
10" table saw20006000
Hot water heater50005000

 

Electric Motor Wattage Requirements

Electrical motors present special electrical startup considerations. They can require up to three times their rated running wattage to start. Motor nameplates generally will show starting watts, some as high as nine times the running wattage. Check the nameplate to be sure. Be certain to use the starting watts when figuring the correct electrical load requirements. Motor load requirements are listed below:

Motor Rating HPApproximate Running WattsUniversal Motors Small ApplianceReduction Induction MotorsCapacitor Motors
1/8275400600850
1/44005008501050
1/34506009751350
1/260075013001800
3/4850100019002600
11000125023003000
1 1/21600175032004200
22000235039005100
33000355052006800
** Motors of higher HP are not generally used.

 

Water Well Pump kW Requirements

Pump HP RatingExternally Regulated GeneratorInternally Regulated Generator
Min. KWMin. KVAMin. KWMin. KVA
1/31.51.91.21.5
1/22.02.51.51.9
3/43.03.82.02.5
14.05.02.53.125
1 1/25.06.253.03.8
27.59.44.05.0
310.012.55.06.25
515.018.757.59.4
7 1/220.025.010.512.5
1030.037.515.018.8

 

Notes:

  • It is recommended that the generator be started before the pump motor is turned on.
  • A majority of industrial generators are externally regulated. Generators must be sized to deliver at least 65% of the rated voltage during motor starting to ensure adequate motor starting torque.
  • Industrial generators typically produce 300+ percent of rated capacity for 15-20 seconds during electrical surges.
  • To convert KW into watts multiply KW (x) 1000.

Back to top


Q: How do I convert AMPS to kW or KVA?

A: Use the following conversion charts:

3 Phase Amperes - 80% Power Factor

KVA
KW
208V
220V
240V
380V
416V
440V
480V
6.3
5
17.5
16.5
15.2
9.6
8.6
8.3
7.6
9.4
7.5
26.1
24.7
22.6
14.3
13
12.3
11.3
12.5
10
34.7
33
30.1
19.2
17.3
16.6
15.1
18.7
15
52
49.5
45
28.8
26
24.9
22.5
25
20
69.5
66
60.2
38.4
34.7
33.2
30.1
31.3
25
87
82.5
75.5
48
43.4
41.5
37.8
37.5
30
104
99
90.3
57.6
52
49.8
45.2
45
36
125
118
108
68
62.5
59
54
56.3
45
156
147
135
85.5
78
74
68
62.5
50
173
165
152
96
86
83
76
75
60
208
198
181
115
104
99.6
91
93.8
75
261
247
226
143
130
123
113
100
80
278
264
240
154
139
133
120
125
100
347
330
301
192
173
166
150
156
125
433
413
375
240
217
208
188
187
150
520
495
450
288
260
249
225
219
175
608
577
527
335
304
289
264
250
200
694
660
601
384
347
332
301
312
250
866
825
751
480
434
415
376
375
300
1040
990
903
576
521
498
451
438
350
1220
1155
1053
672
607
581
527
500
400
1390
1320
1203
770
694
665
602
625
500
1735
1650
1504
960
868
830
752
750
600
2080
1970
1803
1141
1042
985
903
812
650
2257
2135
1958
1236
1129
1067
978
937
750
2605
2463
2257
1426
1303
1232
1128

 

Single Phase Amperes

KVA
120\240
5
20.8
8
33.3
10
41.6
15
62.5
20
83.3
25
104
30
125
35
145
40
166
45
187
50
208
60
250
65
270
76
312
80
333
100
416
125
520
150
625
175
729
200
833
225
937
230
958
260
1041
275
1145
300
1250
350
1458
400
1666
425
1770
450
1876
500
2083

 

Nema Codes for Starting KVA/hp 3 Phase Motors*

CODE
STARTING KVA/HP
TYPICAL SIZE RANGE
CODE
STARTING KVA/HP
TYPICAL RANGE
A
0 - 3.15
-
L
9.0 -10.0
1 HP
B
3.15 - 3.55
-
M
10.0 - 11.2
Less than 1 HP
C
3.55 - 4.0
-
N
11.2 - 12.5
-
D
4.0 - 4.5
-
P
12.5 - 14.0
-
E
4.5 - 5.0
-
R
14.0 - 16.0
-
F
5.0 -5.6
15 HP and up
S
16.0 - 18.0
-
G
5.6 - 6.3
10 HP
T
18.0 - 20.0
-
H
6.3 - 7.1
7.5 and 5 HP
U
20.0 - 22.4
-
J
7.1 - 8.0
3 HP
V
22.4 and up
-
K
8.0 - 9.0
2 and 1-1/2
   


Back to top


Q: How do I apply generator sets to motor loads?

A: Applying Generator Sets to Motor Loads
By Robert A. Barr, Product Specialist, Kohler Co., Generator Division © 1983 by KOHLER CO.

Motor starting is one of the major applications of both prime power and standby generator sets.