First, the easy answer: our high-voltage transmission system (between 49 kV and 735 kV) is a three-phase network.
Now for the more complicated answer: electricity at medium voltage is supplied via either the single-phase (14 kV) or three-phase (25 kV) system.
Our distribution network consists of approximately 40% three-phase medium-voltage lines (25 kV). The decision to build a single-phase or three-phase network depends on customers’ electricity needs. For example, to move large volumes of electricity from one region or municipality to another, we usually build a three-phase medium-voltage network (25 kV).
Homes and small businesses generally receive a low-voltage supply (120/240 V) via the 14 kV single-phase network. The 25 kV three-phase network is mainly used to supply 347/600 V to larger businesses and institutional or industrial buildings.
To find out more about our network, visit the Understanding Electricity section of our Web site.
If you have any questions about the power supply to your home or business, feel free to contact our customer service representatives by visiting http://www.hydroquebec.com/residential/customer-services/customer-reach-us/ (residential customers) or http://www.hydroquebec.com/business/customer-services/ (businesses).