Standby electric generators

Unavoidable events such as ice storms, high winds, equipment failures, and accidents can create power failures. Rural areas are at greater risk, with longer distances of electrical distribution lines being exposed to severe weather and other hazards.

During a power failure, a properly-sized and well-maintained standby generator can be a life saver. Electricity can be restored within minutes with a manual-start generator, or in seconds with an automatic-start unit.

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Standby Generators

A standby generator can be a life saver, but a safety hazard as well if it is not properly installed. Learn how to properly restore and operate outdoor and portable standby generators.

Play video: Standby Generators. (1:00)

Generator size

Most portable generators for homes range from 4,000 to 12,000 watts. Their size and cost depend on how many electrical devices you want to run at the same time.

Power requirements for typical household appliances
Appliance Start-up watts Running watts
Refrigerator 2,500 800
Furnace (natural gas) 1,400 700
Microwave 750
Radio 100
Coffee maker 850
Well pump 2,000 750
Sump pump 1,400 750
Total watts 4,700

These appliances need a total of 4,700 watts to run, however a 4,700-watt generator is not large enough. Appliances with motors generally need up to 4 times as much wattage to start as they do to run. For example, an 800-watt generator would keep the refrigerator going, but it would take a 2,500-watt generator to start it. If a generator is too small to handle start-up watts, it can slow down when overloaded, and possibly starve motors of voltage and damage them.

Turn devices off to allow larger loads to start. After starting the generator, turn on circuit breakers to your motors first — one at a time, from largest to smallest. In the sample list, it would be the refrigerator, followed by the well pump, furnace, and sump pump. To make sure your generator has adequate start-up power, take your list of power requirements to your supplier for advice. The supplier can also ensure that in addition to wattage, the horsepower rating of the generator is sufficient to handle your essential loads.

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Essential loads panel

An essential loads panel looks like a smaller version of your main breaker service panel and should be mounted close to it. Essential devices you want to run with your generator (the essential loads) are disconnected from the main service panel and wired into the essential loads panel. The panel generally has from 6 to 10 branch circuit breakers available to handle your essential devices. The essential loads panel is wired to a transfer switch, which has 2 positions:

  • Hydro position – Used during normal operation. Power from your main panel runs to your essential loads panel to feed your essential loads.
  • Generator position – Used during a power outage. Power from your generator runs to your essential loads panel so that it can feed your essential loads.

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The transfer switch

The transfer switch is mandatory under the Canadian Electrical Code. It sits between your essential loads panel and your main service panel. The transfer switch ensures that the generator cannot feed power back into the hydro lines. If that were to happen, power from the generator could put Hydro crews working on the lines at risk of injury or death. Permanent wiring from the transfer switch to the outside of your house must be sized to the output rating of your generator. The permanent wiring terminates in a recessed male connector, located on the outside of your home (or on the farm pole). The recessed male connector accepts a female plug on the cord from the generator.

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Installation

You must obtain electrical permits before work starts.

  • A licensed electrician should do the electrical work that connects your transfer switch to the electrical system, look after necessary inspections, and ensure that all local codes are met.
  • Use only approved electrical equipment in your installation.
  • Consider installing a surge protector in the essential loads panel. Because of the uncertainty of the power quality from portable generators, sensitive loads can sustain permanent damage.

Although a surge protector cannot guarantee complete protection from all types of surges, it will afford some protection.

View typical residential and rural service standby generator connection diagrams (PDF, 119 KB).

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Starting up and shutting down

These are standard instructions for starting a standby generator. Consult your manual for specific information on your particular model.

Before using standby power, it is recommended that you protect your equipment by installing a surge protector in the essential loads panel.

During a power outage

  • Wait 3 to 10 minutes to check if the utility re-closer system restores power. If not, prepare to start your generator.
  • Turn the transfer switch to the generator position.
  • Turn off the individual essential loads branch circuit breakers in the essential loads panel. This will avoid overloading the generator when you connect it to the panel.
  • Position the generator outdoors in a well-ventilated site.
  • Plug the male end of the outdoor cord set into the portable generator, and the female end into a weather-proof male receptacle on the outside wall of your house.
  • Fuel and start the generator. Wait a few minutes to allow for the speed and voltage to stabilize.
  • Close the essential loads branch circuit breakers 1 at a time (largest loads first).
  • Ensure that the generator is not overloaded and is delivering full voltage and frequency (speed).

When power is restored

  • Wait 15 to 20 minutes to ensure that the Hydro power is stable.
  • Turn the transfer switch to the Hydro position.
  • Shut down the generator. Unplug and store the generator and cable.
  • Drain gasoline from the generator and run the generator dry to facilitate future starting.

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Safe operating tips

  • Hire a qualified electrical contractor to install the unit.
  • Do not work on live circuits or perform work that you're not technically qualified to do.
  • Handle output cables or terminal box wiring with caution; they can be deadly.
  • Check that you have the following components in addition to the generator itself: a transfer device or panel, and proper connection cords and receptacles.
  • Ensure all components of the generator carry safety approved labels.
  • Disconnect from utility service before starting.
  • Ensure the unit is properly grounded before use.
  • Do not use a portable generator in a flooded basement. Water and electricity are a dangerous combination.
  • Be sure your hands are dry and you are standing in a dry place when operating a generator.
  • Never remove or tamper with safety devices.
  • Remember the generator is a fuel driven device that requires proper ventilation to guard against carbon monoxide poisoning.
  • Never operate a generator in your house, garage, or other enclosed building. Carbon monoxide is a colourless, odourless, and deadly gas.
  • Keep children away from generators. Many engine parts are very hot during operation, severe burns may result if touched.
  • Stored fuel creates a fire/explosion hazard. Under the National Fire Code, only 5 litres of fuel may be stored in a residential dwelling, or 30 litres in a garage/shed. Call your local fire department for requirements in your area.
  • Never re-fuel a generator when it is hot, or while the engine is running.
  • Good ventilation for your generator is critical, since overheating will damage the generator and render the warranty invalid.

Larger standby generators

Larger standby generators usually develop 8,000 watts or more. They are engine driven or tractor driven (using the power take-off or PTO on the tractor) and may have automatic or manual starting systems.

  • Keep all guards and shields in place to protect the operator from moving parts.
  • Never shut off the generator when under load.
  • Following severe weather, always check for downed wires. Running a generator could energize them.
  • Always repair or service your generator with the engine stopped and the starting system disabled. On an automatic start generator, this means locking out the switch gear and automatic transfer switch on the generator you are repairing or servicing. This makes sure that the generator does not try to start if an outage occurs when you are doing your work.
  • Before you service a generator driven by a PTO, turn off the tractor and disconnect the PTO.
  • On PTO driven units, always set the tractor brake before starting the generator.
  • Use extreme care in wet conditions. The output voltage of a generator can cause a fatal electric shock.

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