« Power quality is a term that is used to define the characteristics of the electric current, voltage and frequencies at a given point in an electric power system, evaluated against a set of reference technical parameters. » 1
1. As defined by the International Electrotechnical Commission (IEC)
The Hydro-Québec distribution system supplies electricity at voltages within the range recommended for low-voltage power systems by Canadian Standards Association (CSA) Standard CAN3-C235-83.
If you find that your supply voltage is outside the normal range (for example, not between 110 V and 125 V for a 120-V supply), contact customer services at 1 -800 -790-2424.
Want to know more about low voltage?
Range of voltage variation at connection point
under CAN3-C235-83
| Standard operating conditions | Minimum | Maximum |
|---|---|---|
|
Single-phase system 120/240 V (volts) |
110/220 V | 125/250 V |
|
Three-phase system 4 conductors 120/208 V (Y) |
112/194 V | 125/216 V |
|
Three-phase system 4 conductors 347/600 V (Y) |
318/550 V | 360/625 V |
|
Three-phase system 3 conductors 600 V |
550 V | 625 V |
| Extreme operating conditions | Minimum | Maximum |
|---|---|---|
|
Single-phase system 120/240 V (volts) |
106/212 V | 127/254 V |
|
Three-phase system 4 conductors 120/208 V (Y) |
110/190 V | 127/220 V |
|
Three-phase system 4 conductors 347/600 V (Y) |
306/530 V | 367/635 V |
|
Three-phase system 3 conductors 600 V |
530 V | 635 V |
Note: If voltage remains within the range for normal operating conditions, Hydro-Québec is not required to make improvements or take corrective action. If it remains within the range for extreme operating conditions, improvements or corrective action should be taken on a planned and programmed basis but not necessarily on an emergency basis. If the voltage exceeds the broader range, Hydro-Québec must take urgent action to remedy the situation.
You’ll find more information about low voltage in Characteristics and Target Values of the Voltage Supplied by the Hydro-Québec Medium- and Low-Voltage Systems (In French only).
Y: Three-phase star connection, grounded neutral.
Voltage disturbances
Voltage disturbances are power quality disturbances that can be caused by external phenomena affecting the power system, such as storms, or by your home’s electrical installation.
Have you noticed your lights flickering? Voltage disturbances may affect some of your more sensitive electronic equipment, such as CD and DVD players, televisions and computers.
While Hydro-Québec operates and maintains the power system to exacting standards, voltage variations cannot always be avoided. Protecting your electric and electronic devices is your responsibility.
Guarding against voltage disturbances
Plug your electronic devices into a CSA- or ULC-compliant power bar equipped with surge protection or an uninterruptible power supply.
When a storm is approaching, a power interruption is scheduled, or you plan on being away for a long period, unplug your electronic devices or shut off the power bar.
All work on your electrical installation must be performed by a master electrician, in accordance with the Québec Electrical Code.
Before you purchase a new home, have the electrical installation and grounding system inspected by a master electrician to avoid any unpleasant surprises.
Avoid plugging devices into the same circuit as a motor-powered appliance, such as a dishwasher or refrigerator.
Electrical equipment that can create a sudden current demand of 100 A or more, such as very powerful heat pumps (geothermal or not), may not be connected without Hydro-Québec’s written consent. You are responsible for any power system modifications needed for the installation of your equipment.
In general, choose CSA- or ULC-certified equipment.
If you experience major and repeated voltage disturbances, contact customer services at 1 -800 -790-2424. After reviewing the situation, the Hydro-Québec representative may ask you to have a master electrician check your installation.
You can find out more about your rights and obligations and those of Hydro-Québec in the Conditions of Electricity Service [PDF, 1,5 MB] and in Standard E.21-10 (In French only) [PDF, 7.66 MB] Low-Voltage Electrical Service (Blue Book).