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The distribution system delivers electricity from the high-voltage transmission network to end-use customers through a network of medium- and low-voltage infrastructure.
While transmission systems move electricity across large geographic regions, distribution systems operate at a local level and are responsible for connecting individual customers to the grid.
Distribution networks must maintain reliable electricity service while accommodating changing electricity demand, distributed generation, and evolving grid technologies.
In Ontario, distribution systems are operated by Local Distribution Companies (LDCs) and regulated by the Ontario Energy Board (OEB).
Distribution Network
A distribution network is the system of substations, feeders, transformers, and service connections that delivers electricity from the transmission system to end-use customers.
⚡ Distribution systems are becoming more complex as electricity is increasingly generated closer to where it is consumed.
The growing adoption of rooftop solar, battery storage, and electric vehicles is transforming distribution networks from one-way delivery systems into two-way energy networks.
Distribution systems typically operate in a hierarchical structure consisting of several voltage levels.
Electricity arriving from the transmission network enters distribution substations, where voltage is reduced to distribution levels.
Typical distribution voltages in Ontario include:
Substations also contain equipment used to monitor and control power flows.
Distribution feeders are medium-voltage lines that distribute electricity throughout a local service area.
These feeders connect substations to:
Utilities design feeder networks to balance reliability and cost.
Transformers located along feeders reduce voltage further to levels used by customers.
Typical customer voltages include:
Service connections provide the final link between the distribution network and customer premises.
Distribution systems may be configured using different network designs.
Common configurations include:
Most distribution systems are radial, meaning electricity flows along a single path from the substation to customers.
Advantages:
However, outages on a radial feeder can interrupt service to many customers.
In dense urban areas, distribution networks may be meshed or networked, allowing electricity to flow through multiple paths.
Advantages include:
These systems are more complex and expensive to operate.
Distribution systems are increasingly integrating Distributed Energy Resources (DERs).
Examples include:
DERs can both consume and produce electricity, requiring distribution networks to manage two-way electricity flows.
Utilities must upgrade infrastructure and monitoring systems to accommodate these changes.
Distribution utilities are responsible for maintaining reliable service within their territories.
Operational responsibilities include:
Many utilities are adopting smart grid technologies that allow for improved monitoring and automation of distribution networks.
Local Distribution Companies operate under regulatory oversight from the Ontario Energy Board (OEB).
The OEB regulates:
Regulatory oversight ensures that distribution utilities provide reliable service while keeping electricity rates reasonable.
Related topic:
Ontario Energy Board
Consider a residential neighbourhood experiencing rapid growth in rooftop solar installations.
This example illustrates how distributed generation is changing the traditional operation of distribution networks.
➡ Next Topic:
Independent Electricity System Operator (IESO)
This topic explains the role of the organization responsible for coordinating Ontario’s electricity grid and operating the province’s wholesale electricity markets.
Last Updated: 2026-03-26