Blurred image of a Hydro Ottawa employee walking in the basement of a substation.


This glossary is a collection of electricity terms related to our industry and the work that we do.

Ampere (A) is the unit of measurement of an electric current. The typical home has a 100 or 200 amp electrical service.

The Canadian Electricity Association (CEA), founded in 1891, is the national association of the Canadian electricity industry. The CEA encourages innovations and improvement in Canadian electricity services through programming and information distribution. Its focus areas include economic, environmental, and societal issues within Canada’s power industries. Members of the CEA ensure the reliable generation, transmission, and distribution of electricity across the country.

A Current is a flow of electrical charge. It can be compared to the rate of flow of water in a pipe; just as water moves through a pipe, electrons more through a conductor. Current is typically measured in amperes (or amps).

The Electrical Safety Authority (ESA) is the provincial organization responsible for electrical safety in Ontario. The ESA manages certain electrical regulations, such as the Ontario Electrical Safety Code and the regulation that applies to Hydro Ottawa’s infrastructure. It is also responsible for public electrical safety and sets the safety standards for wiring installations, equipment and appliances across the province.

The Electricity Distributors Association (EDA) provides Ontario's local electricity distributor companies (LDCs) with advocacy and representation in the legislative and regulatory environment and the electricity market in Ontario.

Grounding is the process of mechanically connecting isolated wires and equipment to the earth to ensure the wires and equipment remain at the same potential (same voltage) as the earth (ground). A grounding wire provides an electrical current with the shortest path to the ground. This ensures that, should a circuit malfunction, the current passes through the grounding wire to get to the earth rather than through a person.

Hydro One (Hydro One Networks Inc.) operates the transmission systems in Ontario and provides generation and electrical distribution to most of Ontario’s rural customers. Hydro One is wholly owned by the Province of Ontario.

Isolation of service is a safety measure that involves the temporary disconnection of an electrical service, by Hydro Ottawa, when a customer (or a customer’s hired contractor) will be performing work near our electrical equipment. An isolation of service can also be referred to as a disconnect/reconnect.

Kilowatt-hour (kWh) is the unit we use to measure the electricity you consume. One kilowatt equals 1,000 watts. Using one kilowatt of power for one hour equals one kilowatt-hour. A 100 watt light bulb turned on for 10 hours would use one kilowatt-hour of electricity.

A Meter is an electronic device that records electrical consumption. Smart meters transmit readings automatically to a collector that communicates with a central system.

A Meter base is a mounted grey box that houses a smart meter. The sizes and types of meter bases vary depending on the size and form (overhead or underground) of electrical installations. Installation and maintenance of a meter base is the customer’s responsibility.

Non-electrical Maintenance includes tree trimming, painting, replacing siding, and other kinds of maintenance that do not require work to be performed on the electrical system, but that may pose electrical safety hazards and therefore require a service isolation.

Ohm (Ω) is the measure of resistance to the flow of current.

The Ontario Electricity Financial Corporation (OEFC)  manages the debt of the former Ontario Hydro and determines how electricity consumers will pay down this stranded debt. It is also responsible for managing existing power purchase agreements with non-utility generators in the electricity market, and for administering other assets, liabilities, rights and obligations that were not transferred to another of the Ontario Hydro successor corporations.

The Ontario Energy Board (OEB) is the regulator of Ontario's electricity and natural gas sectors. It licenses all market participants, including Hydro Ottawa. The OEB is responsible for establishing a regulated rate plan for low-volume and designated electricity consumers, as well as for the implementation of energy policy in Ontario as directed by the Ontario Ministry of Energy.

Ontario Power Generation (OPG) is an Ontario-based electricity generation company whose principal business is the generation and sale of electricity in Ontario. Its focuses are the efficient production and sale of electricity from its generation assets, and maintaining a safe, open and environmentally responsible operation.

Overhead wires are above ground wires of different voltages that supply power to our customers.

Padmounted transformers are ground mounted transformers that reduce – or “step down” – voltages to the lower level that end users will need. Padmounted transformers vary in size and are usually green and square in shape.

Point of attachment is the place where electrical wires come together outside and attach to a building. It resembles a spool.

Point of Demarcation is the point on the service where Hydro Ottawa’s responsibility for equipment ends and the Customer’s responsibility begins. The point of demarcation will vary depending on the type (residential or commercial) of the service.

Pole mounted transformers are mounted on distribution poles near the primary lines. They reduce – or step down – voltages to the lower level end users will need. Pole mounted transformers vary in size and are a cylindrical shape.

Resistance is the prevention of the flow of an electrical current in a material. Different materials have different resistance to the flow of electricity. Very high resistance materials are called insulators, while the low resistance materials are called conductors. Resistance is similar to the effect of friction on the flow of water in a pipe; water flows more freely in a large pipe just as the current flows more freely in a conductor, while less water flows in a small pipe just as the current is weaker in an insulator. Resistance is measured in ohms (Ω).

Service drop is the overhead line that carries electricity from a distribution pole to a building. The service drop is installed and maintained by the Hydro Ottawa.

A Service Layout is completed upon customer request. When a customer begins a project that will involve electrical work, a Hydro Ottawa service technician will provide the customer with details on the electrical work that will need to be completed as well as how much the work will cost. Hydro Ottawa completes Service Layouts free of charge.

A Standpipe is a PVC or metal pipe that is attached to a building and houses the electrical wires running into a meter base.  Installation and maintenance of standpipes are the customer’s responsibilities. A standpipe can also be referred to as a service mast.

A Triplex wire is three intertwined insulated wires that  runs from a distribution pole to the building. Triplex wires are usually single phase and made of aluminum. They supply the electricity to a building.

Underground locates provide customers with information about where there are underground wires on their property. They are a necessary step to any construction or renovation project that involves excavation. . To request an underground locate, please contact Ontario One Call at 1-800-400-2255 or online at

Underground wires range in voltage and are usually contained in PVC pipe or duct structures. They supply power to our customers.

An Upgrade – or service upgrade – can involve increasing the amperage of the electrical panel in a home  from a 100 to a 200 amp service, adding meters, moving the meter outside, or updating the electrical equipment in the home to meet current electrical code.

Voltage is the difference in electrical potential between two points in a circuit. It is the force that causes the flow of electricity, and it is measured in volts (V). Voltage can be compared to water pressure; just as increasing the water pressure in a pipe causes more water to flow, increasing the voltage in an electrical circuit causes more electricity to flow through the conductor.

Watt is a unit used to measure how much electricity a device consumes. Watts are the rate at which  a certain number of amperes pushed by a certain number of volts, and can be calculated by multiplying volts by amperes (watts = volts x amperes). Most electrical appliances indicate on their labels the watts and amperes they use.

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