Agricultural Electrical

Elite Agri Solutions strives to provide background information on topics which are hard to research. In cases where no reputable print resources were available for us to reference, we interviewed industry experts, so it is inevitable that the contents of this document will contain inaccuracies and bias. Use this as a resource to help you ask the right questions, not as a source of definitive answers. Elite Agri Solutions and its employee will not be responsible for the consequences of any decision made based on this guide. Where text or data has been copied directly, the sources have been noted, otherwise it can be assumed that all the information in this guide has only been curated by Elite Agri Solutions and is not our original property.

Information in this document has been gathered from interviews with electrical contractors, Hydro One, Equipment Manufacturers and OMAFRA Fact Sheets.

Responsibilities/Workflow

  • Verify electrical equipment with suppliers
  • Provide rough plan to electrician with loads and equipment locations
  • Contact Hydro One (or appropriate provider)

In order for any electrical system to be efficiently installed and of maximum value in the long term, the proper leg work must be put in by the farmer to ensure that the system meets the electrical needs of the operation today and allows for reasonable expansion in the future. The physical infrastructure requires adequate planning as well, poorly placed conduit can negatively affect airflow, and poorly placed equipment can negatively affect expansion or renovations in the future.

For best results, the farmer should put some serious thought into their electrical system early in the construction process.

Regardless whether you think you need a new service connection, a service upgrade, or you are just adding a couple branch circuits to an existing panel it is important to know what your electrical loads are going to be. This means that all ventilation, feeding, manure, lighting, water and other equipment should be finalized as early as possible. If possible, gather the name plate specifications for each electrical load.

The electrician should be made aware of any future plans. For example, if you are planning on switching to automated feeding with a stationary TMR in the future, the electrician needs to ensure the transformer and panel has enough capacity to allow for a high amp branch circuit to be wired in the future, or if the motors are large enough a three-phase connection will be necessary.

Conduit and fixture placement should be included in this written plan (electricians are not ventilation experts and need guidance on where conduit is best placed for air flow)

Make sure the electrician is aware of any future building plans so that the appropriate accommodations can be made. It is typically much cheaper to increase the capacity of the system now, than in the future.

It is always best if you can get manufacturer stats on all electrical loads being installed in a barn, but for cases where you might not know yet the exact equipment you are going to install, use a table like the one below to estimate electrical loads.

Table 1 Approximating Full Load Current of Single-Phase Electric Motors

Power

Full Load Current (amp)

(hp)

(kW)

115 V

208 V

230 V

1/6

0.13

4.4

2.4

2.2

1/4

0.19

5.8

3.2

2.9

1/3

0.25

7.2

4.0

3.6

1/2

0.38

9.8

5.4

4.9

3/4

0.56

13.8

7.6

6.9

1

0.75

16

8.8

8

1 1/2

1.1

20

11

10

2

1.5

24

13.2

12

3

2.3

34

18.7

17

5

3.8

56

30.8

28

Table 2 Various Electrical Loads Taken from Barn Equipment Manufacturers

Device

Max Amp Draw

Running Amp

Typical Supply Voltage

Flex Auger Drive (1.5 hp)

25

240V

Well Jet Pump (0.5hp to 1.5hp)

8.4 – 13.2

120V

4.2 – 6.6

240V

Submersible Well Pump (0.5hp to 1.5hp)

12

120V

6-12

240V

Incandescent 10-17 L/W

0.90A/1000Lumens – 0.53A/1000Lumens

110V

Compact Florescent 65 – 75 L/W

0.14A/1000Lumens – 0.12A/1000Lumens

LED 27 – 96 L/W

0.34A/1000Lumens –0.095A/1000Lumens

48” exhaust fan (1 – 1.5hp)

4.5-7.5

240V

36” exhaust fan (1/2 -3/4hp)

3-7

240V

24” exhaust fan (1/2hp)

2-5

240V

18” exhaust fan (1/3hp)

1.5-2.5

240V

Circulation fan (1/2hp)

2-5

240V

Inlet/Curtain Actuator

0.6-1.2

240V

1.2-2.4

120V

Milking Equipment

Variable, Confirm with equipment supplier.

Line Extensions

If there is not adequate service at the intended building site, Hydro One will either upgrade or install new service to meet your needs. The specifics of line extensions vary widely from case to case and must be discussed with Hydro One for more information. Though you must contact Hydro One for a site-specific quote, it is a rule of thumb that it will cost over $200 000 per mile to develop a three-phase power supply on a road where it doesn’t already exist.

Hydro One will come out to the site and measure the distance required. They will also stake the line, for which there is a fee. A Class C estimate will then be calculated, these have a variability of ± 50%. Hydro one will also consider a discounted cash flow calculation which gives the farmer credits towards the line construction based on their projected demands. A customer with higher demands will get more credits because, hydro one will make more profit off them in the long run.

A UCCP protects the farmer for five years if neighbours decide after the line is installed that they want to connect to it. Under this circumstance the parties making new connections to the line must pay those who paid for the line extension originally.

The work for new line extensions is split into two categories, work that is contestable and work that is non contestable. Contestable work can be completed by either Hydro One or by contractors provided it passes a line inspection done by Hydro One, when work is complete.

New Connections

For any connections larger than 400-amp single phase, a New Customer Connection Information form must be completed this form is typically completed with the aid of your electrical contractor and will outline your estimated loads based on:

  • Location
  • Panel size
  • Service entrance
  • Number and type of motors
  • Name plate data for large motors (e.g. grain dryer motor)

If a farmer’s draw is large enough, a system impact assessment will be undertaken to determine if the grid can support their needs. Restrictions can be imposed dictating that soft starting be installed on motors or that certain motors cannot all be started at the same time.

If a new connection must be made to a Hydro One distribution network, the following check list must be adhered to:

Step 1: Foundation

The foundation of your site must be complete before a connection can be made. Upon completion of the site foundation, contact Hydro One to schedule an assessment.

Step 2: Site Assessment

A crew will visit your site to complete a comprehensive assessment. Hydro One will create a technical drawing, outlining responsibilities for work required to complete the connection.

Step 3: Contract Package

Hydro One will develop a contract package for your business after the site assessment. You’ll be asked to review the package and return a signed copy to them in order to move onto the next step.

Step 4: Payment

Upon receiving payment and the signed contract package, Hydro One will initiate the pre-work required to establish a connection.

Step 5: Pre-Work

Depending on the connection requirements, your project may require additional electrical work. If this is the case, Hydro One will provide a quote for electrical services for your approval before they continue work.

Step 6: Electrical Safety Authority Inspection

When the pre-work is complete, the ESA will inspect the work. Once the ESA has inspected the property and approved the completed work, Hydro One will connect your business within five days.

Municipal building inspectors have no jurisdiction on electrical other than for emergency exits, emergency lighting etc. The Electrical Safety Authority is responsible for inspection of all other electrical work. The electrician will be adhering to the ESA code and are required to obtain permits from the ESA as well.

Phase

All power in North America, regardless of phase, is 60hz alternating frequency. This means that the polarity of the power is reversed 60 times every second.

Both single and three-phase supplies are available in the following phase increments (provided that distribution can cope meet the demand): 100A, 200A, 400A, 800A, 1200A, 1600A & 2000A. 400A is most common while up to 1600A is seen for larger farms. Your electrician will work through a Hydro One form called the “New Customer Connection Information Form” with you that will be used to determine the capacity of the service required.

Single Phase

Single phase power is supplied to 120V devices via ground, neutral and power wires. The electrons are alternatingly “pushed” or “pulled” into and out of the neutral wire by the power wire.

Split phase power is supplied to 240V devices via a ground and two power wires. The electrons are alternatingly “pushed” or “pulled” from one power wire into the other. The two wires are 180 degrees out of phase with each other meaning their polarities are always opposite. When one wire is “pushing” electrons, the other one is “pulling” them. Some household appliances with high power requirements such as stoves and dryers run on 240V. Most ventilation products operate on 240V because half the amperage is required to do deliver the same amount of power compared with 120V. Amperage is what determines the gauge of the wiring, so lower amperage means less copper in the barn and lower line losses.

Using a 167kVA capacity which is the standard for single phase power distribution the maximum amp supply is 700A. It is possible to overload up to 200% of capacity for short periods of time.

Three-Phase

Three-phase power has three supply lines and a neutral line. The three supply lines each provide 120V each 120 degrees out of phase with each other. The system is always balanced as each phase is cycled through, meaning that at any given time electrons are being delivered by one (or two) wires and being taken away by two (or one) wires. As a result, three-phase power has 1.7 times more power than the equivalent voltage single phase source making it more efficient. Depending on the size of your loads either a 347/600 V three-phase or a 120V/208V three-phase service can be installed, the smaller of the two is enough for most farms.  As a rule of thumb, three-phase motors smaller than 1hp are more expensive than their single-phase counter parts, while larger motors cost less in three-phase configurations. Wiring costs in the barn are reduced in three-phase systems because the amperage required to provide the same amount of power is reduced. With a 120V/208V three-phase supply, 120v circuits are simply wired off any one of the supply lines and the neutral line.

Benefits of Three-phase:

  • Lower wiring cost
  • Lower capital cost for large motors
  • Capability of running larger motors than single phase
  • Efficient operation of large motors
  • Lower stray voltage (electrons are returned on supply lines instead of a grounded neutral line)

If readily available, it is generally accepted that three-phase power is a requirement for any facility that is running motors over 5hp or if there is major expansion on the horizon that would utilize large hp motors.

Efficiencies are dramatic with large three-phase motors but can be gained on smaller motors as well, such as ventilation fans using 1.5hp motors. Efficiencies on the small scale might be marginal, so the cost benefit should be weighed.

For example, using data from two models of 48” exhaust fans from one manufacturer that are identical except for the motor. If both run continuous for half the year and using a hydro rate of $0.1 a kW/h, the difference in operating cost is $4/year. With the same conditions for a different manufacturer, the savings are $15/year. In either case the long-term savings are probably not worth the cost of upgrading to a three-phase hook up. You compare costs of operating different fan combinations for yourself by using the formulas in the ventilation section.

Things to know before calling Hydro One to ask for a “ballpark” estimate for a three-phase connection.

  • Approximate proposed location of building (what road)
  • Approximate distance from building site to roadway.
  • If any special ground conditions are present (bed rock near surface, marsh, etc.)
  • Estimated Capacity needed (amp draw of major motors)

Knowing this information, Hydro One will be able to return to you an estimate for the cost of

  • Line extension or upgrade
  • hook up
  • transformer and equipment
  • delivery fee
  • metering & billing

If having access to three-phase electricity at the road is a major factor when considering whether to purchase a property, a visit to the sight or google street view can be used to infer the type of service available. If the poles only have two wires (1 ‘live’ and 1 neutral) it is likely that the service is single phase), while if there are four wires (3 ‘live’ and 1 neutral) it is likely three-phase. Keep in mind that even if there are three-phase wires at the road the grid might not have enough capacity to support your hook up. Unfortunately, Hydro One does not have any general mapping available regarding what type of services they provide. It is up to you to call in with your address and start a work order for them to confirm the potential for service to your building site.

Phase Converter

If three-phase power is not available, and specific equipment is restricted to only operate using a three-phase power supply a few solutions exist to operate the equipment on single-phase, the two most common are.

  • Rotary phase converter. This system uses an idler generator and a control panel to create and balances another phase of power to combine with 120V split phase supply.
  • Static phase converter. Uses a capacitor and a start relay to imitate three-phase for motor start up, then operates “limping” the motor on single phase as it operates. This is only a suitable option for light usage.

An alternative to using a phase converter would be to use a combustion engine with a three-phase generator that will be fired up when large electric motors need to be operated.

Metering & Billing

When a new single-phase service is connected to a building, it is common that for about the first nine months, electricity usage will be billed on a split usage table schedule. This means power usage under 750kW/h is billed at a base rate and all power use above that is billed at a premium rate. After the initial period, the billing is usually transferred over to time-of-use billing.

For three-phase and large single-phase users, an additional meter may be required. Based on your “New Customer Connection Information Form”, you will have to report the estimated power requirements for any equipment you are planning on installing in the next 6 years. Based on this, Hydro One may install a demand meter. When considering large amp drawing equipment it important to know that general service is billed by the kW/h plus a demand charge on top. The demand charge reflects the peak short-term kW draw for the period. In the case of starting up large motors for a short period of time, the demand charge might be far greater than the usage charge for that billing period. Demand charges apply to any service that peaks over 50 kW and increase accordingly.

On Farm Distribution Lines

Any lines that are on your property are the farmer’s responsibility.

Overhead

All poles on the property are the farmer’s responsibility, including the pole where the transformer is mounted. As such, any repairs necessary because of damage done by nature or humans is the responsibility of the farmer. Poles on road allowances are Hydro One Responsibility.

Typical is class 5 poles (40ft) for lines and a class 4 or 3 (40ft) for the transformer pole.

Minimum horizontal separation between secondary (lines between the transformer and buildings) and structures is 2m (6’ 6”) except for the point of attachment. Minimum ground clearance is 6m (20ft).

Private electricians are usually hired to source and install poles and overhead wiring, they will run the wiring right up to the road leaving the final hook up and transformer installation for Hydro One.

The transformer will be supplied, owned and maintained by Hydro One.

Buried

Buried cables must have a protective casing and therefore, are more expensive than overhead wires. They have the benefit of having less maintenance and do not interfere with above ground land uses. The trench can be dug by the farmer or by a contractor based on Hydro One specification. An electrician must then install the wire and run the wiring up conduit on the primary service pole where it is left for Hydro One to hook up.

The transformer must be pad mounted and is installed by Hydro One. The transformer is owned by hydro one, however the farmer must pay a fee equivalent to the difference in price between a pole mounted and a pad mounted transformer.

Telecommunications can share the same trench but must be in their own conduit.

Preferred routing for gas service and hydro connection is be in separate trenches entering the building on opposite sides. If it is unavoidable, hydro and gas can both be in the same trench provided they are separated by a minimum of 300mm in all directions.

General specifications for trenching for single phase secondary distribution can be found on the Ontario Hydro website by searching “Secondary Underground Trench Specifications”.

Wiring in Buildings

Stray Voltage

Stray voltage is a result of the grounded neutral distribution system in place in Ontario. In this system the neutral wire is grounded at various points along the system. The level of potential voltage typically radiates out from the grounding locations decreasing as it gets further away. If a connection is made between two earth contacts with different potential voltage levels, a current will flow between the two points.

When is it an animal that completes this connection, the electrical resistance of the animal’s body causes a voltage to be felt by the animal. This often occurs when the animal contacts metal stabling or water bowls. The effects of stray voltage are particularly a concern for dairy animals. Dairy cows are particularly sensitive to stray voltage and the environment in the dairy barn has many wet surfaces and conductive points of contact.

If you suspect stray voltage may be negatively affecting your livestock, Hydro One will complete a Stray Voltage Assessment. This service is free and can be called upon as soon as a problem is suspected. It cannot be done on a proactive basis, so attention should be paid to avoidance behavior when animals are first introduced to a barn so that any problems with a new build can be addressed promptly.

Electricians who specialize in agricultural service, such as Gaffney Electric Solutions can also access and take measures to control stray voltage on farm. It has been noted that though Hydro One’s stray voltage service is “free” it is a lengthy process and they are generally reluctant to offer solutions.

Three-phase circuits don’t produce stray voltage because electricity is always returned down two of the three power wire. In a single-phase system current must return via a grounded neutral wire, hence producing fields of potential difference in the ground.  240V single-phase circuits also have no potential for stray voltage because the current only ever passes between the two live wires instead of using the neutral ground.

Stray voltage is hard to accurately measure; however, the following values have been taken from the Ontario Energy Board’s “Farm Stray Voltage: Issues and Regulatory Options”

Figure 1 Stray Voltage Threshold

Voltage Level

Species Threshold

Cows

2.5

Sheep

5

Pigs

3

Variable frequency drives are becoming increasingly popular for ventilation products and for milking equipment. Stray Voltage from VFD’s can be limited by keeping the controller unit as close to the motor as possible and by using VFD cable instead of standard wiring.

It is common to have the main service disconnect outside of the main barn, perhaps in an outbuilding that houses the backup generator. If this is the case the service grounding should be carried into the main barn.

Grounding

It is suggested that electrical continuity be maintained between conductive elements 12” above grade with woven copper conductor. Due to issues with corrosion and inaccessibility, it is recommended that any components bellow 12” above grade be tack welded together. If reinforcing mesh or rebar is used in the floor, it must also be bonded between reinforcing elements and connected to the bonded components above ground so that the entire barn acts as at a single grid, reducing the equipotential differences that can negatively affect livestock.

Because the fundamentals of our grounded neutral single-phase electrical supply in North America, there will always be current flowing through the ground. The best way to deal with it is to have every device grounded to a common grid so that there are no potential differences that livestock can span. Think ‘birds on a hydro wire’.  If there is an unavoidable discontinuity in the equipotential grid, (such as where cattle step off pasture to go out to pasture) creative rebar arrangements can make a gradual equipotential transition.

Branch circuits

All wiring in farm buildings must use copper conductors, aluminum conductors are not permitted. For protected areas exposed to view, plastic coated NMWU -type sheathed cable is acceptable. This can be used where there is no risk of rodent damage and the wire is not permanently or seasonally covered.

It is not recommended to use concealed wiring in any farm building where the winter relative humidity regularly exceeds 50%.

Best Practice is to run all wiring in plastic conduit to protect it from the environment and from mechanical damage.

Protection

If the wiring is exposed to potential damages including rodents, livestock or outdoor conditions, it must be sheathed in PVC conduit.

Heat lamp receptacles must be in the ceiling directly overhead of the lamp so that a lamp will disconnect if it falls or is knocked over.

Wiring size is based on motor running amperage. During start up a motor may draw up to five times the running amperage. Starting motors under load heavy load can cause dangerous circuit heating if not properly protected by circuit breakers. Large start uploads are mitigated by adequate starting capacitors on the motor.

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[1] (Engineering Toolbox)