Structure of Rate L

Billing for Rate L includes the following:

  • An amount for the energy in kilowatthours (kWh) consumed during the period in question.
  • An amount for the billing demand in kilowatts (kW).

Rate L is a monthly rate, which means the amount billed for power is based on a 30‑day period.

If applicable, the following may lower your bill:

Credit for supply at medium or high voltage

Hydro‑Québec’s rates assume that electricity will be supplied at low voltage. If you have equipment to step down the voltage of the electricity delivered to you or if you use electricity at medium voltage or high voltage, that means reduced costs for Hydro‑Québec. In return, you receive a monthly credit on your demand charge. The credit is determined according to the supply voltage.

Adjustment for transformation losses

Hydro‑Québec bills you only for the electricity you use, regardless of where it is metered in relation to the transformer substation. If metering occurs before transformation, the electricity billed will include transformation losses. So that you do not pay for losses, Hydro‑Québec grants an adjustment of per kilowatt (kW) on the billing demand.

The following may also be billed in certain cases:

Optimization charge during the winter period

If in a day during the winter period the maximum power demand exceeds 110% of the contract power, the overrun is subject to a daily optimization charge, expressed in dollars per kilowatt.

For each day during which such an overrun occurs, the amount billed is calculated by multiplying the daily optimization charge by the number of kilowatts making up the highest overrun during the day.

The billed amount will not, however, exceed the monthly optimization charge (or three times the daily optimization charge) applied to the highest maximum power demand recorded during the monthly period in question.

Charge for low power factor

Electrical equipment, whether yours or Hydro‑Québec’s, is designed to operate at a relatively stable voltage. Hydro‑Québec’s rate structure for large‑power customers encourages the maintenance of a power factor of at least 95% at all times.

When large‑power customers make less than optimal use of the electricity provided and have a power factor below 95%, Hydro‑Québec is forced to supply them with additional power and handle the impacts on the power system. The rate structure allows for Hydro‑Québec to bill this excess power to customers.

And when the maximum power demand is below 5,000 kilowatts (kW), customers must still maintain a power factor of 95% or more, or risk being billed at the price of power for excess kilovoltamperes (kVA).

See Helping you understand your electricity rate

Rate L prices in effect

Breakdown of billing

Applicable in certain cases

  • Optimization charges during the winter period
    • Daily charge /kW
    • Monthly charge /kW
  • Credit for supply at medium or high voltage
    • Voltage of 5 kilovolts (kV) to less than 15 kV /kW
    • Voltage of 15 kV to less than 50 kV /kW
    • Voltage of 50 kV to less than 80 kV /kW
    • Voltage of 80 kV to less than 170 kV /kW
    • Voltage of 170 kV or more /kW
  • Adjustment for transformation losses /kW 

Rates in effect as of April 1, . This table does not replace the Electricity Rates document in any way whatsoever.

More information

This information has been simplified. For more details about Rate L, consult Section 1 of Chapter 5 of the Electricity Rates [PDF 1.44 MB].

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Contract power

Minimum demand that a large-power industrial rate customer (Rate L) agrees to pay and that Hydro-Québec must be ready to supply at any time in response to the customer’s demand.


Power used by electrical equipment over a given period of time. Expressed in kilowatthours (kWh), energy is calculated as power, expressed in kilowatts (kW), multiplied by the time during which the power is used, expressed in hours (h).

The formula for energy is as follows: energy (in kilowatthours) is equal to power (in kilowatts) multiplied by duration of use (in hours).


Total amount of electricity supplied at a given time. Expressed in kilowatts (kW), power is the combined effect of voltage, expressed in kilovolts (kV), and current, expressed in amperes (A).

  • Low voltage: Voltage of 750 volts (V) or less.
  • Medium voltage: Voltage of more than 750 V, but less than 44 kilovolts (kV).
  • High voltage: Voltage of 44 kV or more.


Difference in electrical level between two points, expressed in volts (V).


Operation that involves increasing or decreasing voltage through a transformer.

Winter period

Period from December 1 through March 31 of the next year, inclusive.

Maximum power demand

Maximum power measured during a consumption period. It is the higher of the following two values: real power in kilowatts (kW), or a percentage (90% for domestic rates and small- and medium-power rates, or 95% for large‑power rates) of the apparent power in kilovoltamperes (kVA).

Monthly periods

Period of 30 days, which may begin on any day of the month, established by Hydro‑Québec for billing purposes.

Power factor

Ratio of real power (in kW) and apparent power (in kVA). The power factor is expressed as a percentage and indicates the efficiency with which the customer uses the electricity provided. Hydro‑Québec encourages its customers to maintain a power factor of at least 90% or 95%, depending on their rate.

Power demand

Power a customer requires to meet energy needs at a given time. The higher the customer’s energy consumption at a given time, the higher the power demand.


Electricity rate effective April 1, .