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Generator Load Charts

Basic Standby Power Requirements

To design a standby emergency power system for your home or farm, begin by tabulating all of the loads that may operate at one time. The best way is to record the actual loads from nameplates of the electrical equipment directly . If this is not possible, the tables and charts at the end of this chapter will provide a reasonable estimate of loads of the various machines on farms.

When sizing loads for motors on the farm, both the running load and the start up load must be considered. Table 2 lists typical loads for a range of motor horsepower. The start up load may be much higher than listed if the motor must typically start under load. For example, a start up load of 4 times running load may be reasonably accurate if the silo unloader is raised off the surface of the silage but, if it must start when buried in the frozen silage face, the load could be 12 to 20 times normal running load. A good management technique is to minimize the situations where motors need to start under load.

The pie charts were developed from a survey of 177 livestock farms in eastern Ontario. They depict averages and therefore should only be used as a general reference in estimating your farm conditions. The graphs show several things. First of all, the total average electrical load is shown and varies by both farm type and farm size. Secondly, the charts portray the portion of that load that is demanded by each part of the farm operation. For instance, the utility load, which is primarily the farmhouse, averages about 11 kW for all of farms. However, on a percentage basis, it is 76% of the load on sheep farms but only 15% on layer farms because the difference in total demand load.

It is important to also realize that load does not equate to usage. Tables 3 through 8 give an indication of annual consumption of electricity by various farming operations. Consumption is the combination of load and duration. The demand load (kW) is important in determining the size of the emergency generator. Consumption (kWh) is important from the standpoint of energy management and only comes into play in designing the emergency power supply when time of use is a factor. Use Tables 3 -8 to compare power use among various types of loads. For example, in Table 3, a direct expansion bulk tank milk cooler with a heat exchanger uses about 82 kWh of electricity per cow per year as compared to the same unit, without a heat exchanger, uses about 154 kWh per cow per year. Therefore, one way to save energy is to install a unit with a heat exchanger.

To illustrate demand load, a farming operation contains of a number of electrical loads. If none of these loads were ever operated together, the generator size would be based on the largest load only. However, there are two constraints on that design. Firstly, there may not be enough hours in the day to perform each operation in sequence. Secondly, it is typical that a number of loads must operate at the same time in order to accomplish a task. Feeding, for example, may require that a silo unloader, a feed mixer, and a feed conveyor, all operate at once. At the same time, some lights may be on and ventilation fans may be operating. Therefore, the generator size must be based on the sum of all the loads that must operate at one time. If some of those loads are motors then the start up load of the largest motor must also be included. The next consideration is the loads you want to operate at the same time. For instance, you may want to perform both milking and feeding, at the same time, for the sake of convenience or time management. Of course, the ultimate scenario is where all of the farm operations may occur together, as would happen with grid power. Farms that have automatic standby systems will have generators sized for that condition. Most farms will choose an option somewhere between the extremes, based on the specific demands and constraints of that farm. Chapter 3 provides a template that can be used to consider the best options for your farming operation.



Table 1: Typical Equipment Wattage (Farm Equipment)

Farm Equipment Typical Wattage
Bulk Milk Cooler 1500-12,000
Electric Fencer 7-10
Feed Conveyor 800-5,000
Feed Grinder 1,000-7,500
Feed Mixing 800-1,500
Gutter Cleaner 3,000-5,000
Infrared Lamp 250
Milking Machine Vacuum Pump 800-5,000
Milking Parlour Heater 2,000-10,000
Shop Tools 300-1,500
Silo Unloader 2,000-7,500
Space Heater 1,000-5,000
Ventilation Fans 300-800
Water Heater 1,000-10,000
Water Pump 500-2,500
Yard Light 100-500


Table 1: Typical Equipment Wattage (Essential Home Equipment)
Essential Home Equipment Typical Wattage
Electric Heater 600 & up
Freezer 600-1,000
Furnace Blower 400-600
Furnace Oil Burner 300

Furnace Stoker

Refrigerator 400-800


Table 1: Typical Equipment Wattage (Optional Home Equipment)
Optional Home Equipment Typical Wattage
Central Air Conditioner 2,000-5,000
Coffee maker 1,000-1,500
Dishwasher 300 + 1,500 for heater
Electric Clothes Dryer 500 + 4,000 for heater
Electric Fan 75-300
Electric Iron 500-1,500
Electric Range 3,000-4,000
Electric Skillet 1,150-1,500
Kitchen Ventilator 150
Mixer 150
Sewing Machine 200-500
Sweeper 400-1,500
Television 200-500
Toaster 1,200-1,500
Washing Machine 400
Water Heater 1,000-5,000
Water Pump 800-2,500
Window Air Conditioner 1,000-2,500


Table 2: Motor Wattage - Starting and Full-load Running Wattage Required for Single Phase Electric Motors
Motor Horsepower Watts Required
To Start To Run
1/4 1000 215
1/4 1500 300
1/3 2000 400
1/2 2300 575
3/4 3345 835
1 4000 1000
1.5 6000 1500
2 8000 2000
3 12,000 3000
6 18,000 4500
7.5 28,000 7000
10 36,000 9000


Table 3: Electricity used for performing dairy farm operations
(A) Task or operation (B) Loads or area involved
(C) Electricity used
(kWh/year per cow)
Milk cow preparation Washers with sprinkler boosters
18.4 to 19.6
Milking system (by type) Bucket milker
  Bucket milker and transfer
  Parlor – pipeline
  Can cooler
  Direct expansion bulk tank with precooler
  Direct expansion bulk tank without precooler
  Direct expansion bulk tank with heat exchanger
  Direct expansion bulk tank without heat exchanger
Ice bank cooler without heat exchangers
182 to 222
Milking operation Vacuum pump
74 to 76
Water heating Fast recovery without heat exchangers
  Fast recovery with heat exchangers
Feeding Silo unloaders
  Silo unload and silage feeding (system)
  Above unload, feeding plus hammer mill
  Grain grinding/ feed mixing, auto
6.5 to 8.2
Water supplies Well pump
  Livestock watering (outside)
5 to 7
  Livestock watering (inside)
Manure handling Gutter cleaner
  Liquid waste
Space conditioning (lighting) Lighting for milking operations
Space conditioning (ventilation) Milk parlor and milk room
10 to 20

Table 4. Electricity used for performing beef cattle farm operation
(A) Task or operation (B) Loads or area involved (C) Electricity Used
Feeding Silo unloaders
2.1 kWh per lot
  Silo unload and bunk feeders
4.4 kWh per lot
Watering Cattle waterer (outside)
300 kWh per lot
  Cattle/hog waterer (outside)  
  Cattle/hog waterer (inside)
200 kWh per lot
  Pumping and distribution
0.35 kWh per 100 kg
Lighting Feeders/feedlot  
0.33 kWh per 100 kg


Table 5. Electricity used for performing swine farm operations
(A) Task or operation (B) Loads or area involved (C) Electricity Used
Breeding house Air conditioning 3.6-t (4-ton) unit 150 to 220 kWh per sow
  Fan ventilation with foggers 13.5 kWh per sow
Farrowing house Air conditioning 3.6-t (4 ton) unit 93 kWh per sow
  Fan ventilation 41 to 47 kWh per sow-litter
Brooding Cable, in-floor 50 to 100 kWh per sow-litter
  400 W per pen  

Cable, in-floor 300 W per pen

19 kWh per sow-litter

Commercial pads 300 W per pen

40 to 120 kWh per sow-litter
  Heat lamps 250 W per pen 6 kWh/day per sow-litter
Nursery building All uses 16.8 kWh per pig housed
Finishing operation Ventilation of confinement house 10.4 kWh per hog marketed
  Feed augers and lights 0.3 kWh per hog marketed
Watering Outside location 5 to 10 kWh per hog marketed
  Inside location 2 to 3 kWh per hog marketed
  Pumping/distribution 3 kWh per hog marketed
Feed handling Grinding/mixing 2.2 kWh per hog marketed


Table 7. Electricity used for performing poultry farm (layer) operations
(A) Task or operation (B) Loads or area involved (C) Electricity used
(kWh/year per 100 birds)
Production lighting Controlled incandescent lamps
  Controlled light in windowless house
  Controlled light in solar house
  Controlled light in conventional house
Ventilation Fan size and number unknown
Water heating One heater
Feeding Auto-feeders
Egg collection Automatic unit
Egg processing Automatic unit
Egg washer Automatic unit


Table 8. Electricity used for performing poultry (brooding) operations.
(A) Task or operation (B) Loads or area involved C) Electricity used
(kWh/year per 100 birds)
Brooding broilers 1560-W hover units
18 to 44
Whole-house brooding unit Quartz heat brooders
  Space heaters (supplemental)


Table 9. Electricity used for on-farm feed grinding and processing
(A) Task or operation
(B) Primary loads
(C) Electricity used
(kW) (hp)
Feed grinding (hammer mill)
3 (15% corn)
1.8 to 2.7 kWh/t
3 (25% corn)
2.4 to 12 kWh/t
3 (dry oats)
1.9 to 22 kWh/t
1.5 to 5.5 kWh/t
Auto feed grinding systems (mill motor)
9.43 kWh/year per cow
2.13 kWh/year per hog
2.02 kWh/year per bird


This information is provided as a public service, but we cannot guarantee that the information is current or accurate.
Readers should verify the information before acting on it. This information provided and maintained by the Government of Ontario, Canada

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