Considering Three-Phase Power
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 was gathered from Hydro One’s website, Hydro One employee, equipment manufacturer data and private electrical contractors.)
In Ontario, most cities and towns are supplied by independent distribution companies, while most rural areas are supplied by Hydro One. If you search ‘Independent Electricity System Operator’ and ‘Find your local distribution company’ there is mapping available that shows who the local utility is. For the purposes of this document we will presume that most rural users are serviced by Hydro One.
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. It has been anecdotally noted that new connections are typically less expensive than service upgrades. Upgrading a single-phase line to three-phase can cost over a hundred thousand dollars per km. Five years after installation, upgrade costs can no longer be split with new users.
If a new connection must be made to a Hydro One distribution network, they put out this checklist for customers to follow.
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 the 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.
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.
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 are 240V. Most ventilation products operate on 240V because half the amperage is required as 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 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. Three phase that would be needed for farm use is a 120V/208V service. As a rule of thumb, 3 phase motors smaller than 1hp are more expensive than their single-phase counter parts, while larger motors cost less in three phases. Wiring costs are reduced in three phase systems because the amperage required to provide the same amount of power is reduced. With a three-phase supply, 120V single phase circuits are simply wired off of one of the supply lines and the neutral line.
Benefits of Three Phase:
- Lower wiring cost
- Lower cost for large motors
- Capability of running larger motors than single phase
- More efficient operation
- Lower stray voltage (electrons are returned on supply lines instead of grounded neutral line)
It is generally accepted that three phase power is a preferable for any facility that is running motors over 5hp.
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 two models from one manufacturer that are identical except for the motor, 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 three-phase hook up. To compare costs of operating fans for yourself by using the formulas in the ventilation section.
Things to know before calling Hydro One for a “ballpark” estimate for three phase hook up.
- 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)
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
To our knowledge there exists no public mapping that shows where three phase service is available on rural roads. If having access to three phase electricity at the road is a major factor when considering which farms to look at buying, google street view can be used to infer the type of service available without having to make the trip out to the site. 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 (3 ‘live’ and 1 neutral) wires it is likely three phase. Unfortunately, Hydro One does not have any general mapping available regarding what type of services they provide where. 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.
If three-phase power is not available, and specific equipment is restricted to only operate using three-phase supply a few solutions exist to operate the equipment on single-phase, the three most common are.
- Rotary phase converter. This system uses an idler generator and a control panel to create and balance a third 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.
- Combustion engine with a three-phase generator.
Metering & Billing
When considering three phase 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/h 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.
When single phase service to a new build is connected, 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 will more than likely be transferred over to time of use billing.