Standby Generator Canada: Whole-Home Backup, Sizing & Cost

Quick answer

A standby generator is a permanently installed fuel-burning generator connected to the home’s electrical system through approved transfer equipment. Residential systems usually run on natural gas or bulk propane and can start automatically when utility power fails.

The useful buying rule is simple:

Size the backup system around the loads that must operate together, the fuel you will actually use, and the transfer/load-management design. Do not buy it from house square footage or the amperage printed on the main breaker.

And one phrase needs translating before you spend five figures:

“Whole house” usually describes how broadly the backup source is connected. It does not guarantee that every high-demand appliance can run at the same time without load management.

Generac’s current Canadian 200 A service-entrance automatic transfer switch, for example, can manage four HVAC loads and explicitly says that load management can allow a smaller generator to protect the home. That is the architecture distinction retailers often flatten into one shiny “whole home” label.

Use the generator size calculator for the actual electrical load calculation. This page owns the larger decision: standby vs portable/battery, essential vs whole-home integration, natural gas vs propane, installation, winter operation, maintenance, and quote comparison.

Standby generator vs portable generator vs home battery

A standby generator is not the automatic “upgrade” for every home. If outages are rare and you can safely deploy equipment, a portable generator can be much cheaper. If your priority is silent automatic backup for shorter outages, an installed home battery may fit better. Some high-resilience homes use a supported battery-generator hybrid.

How an automatic standby generator actually works

The broad sequence is consistent, but the timing is not universal:

1. The controller detects abnormal or failed utility power.
2. A line-interrupt delay filters brief grid disturbances.
3. The engine cranks and starts.
4. The generator warms up and establishes acceptable voltage/frequency.
5. The automatic transfer switch moves the protected load from utility to generator.
6. When utility power returns and remains acceptable, the switch transfers the load back.
7. The generator runs unloaded through its configured cool-down sequence and returns to standby.

Current Generac 10-26 kW documentation is a useful example, not a national timing rule. It uses a dealer-programmable five-second utility-loss delay and a warm-up period that changes when Cold Smart Start is enabled. Current controllers also use a utility-return verification period before retransfer. Other manufacturers and controller settings differ.

So “all standby generators restore power in exactly 10 seconds” is bogus precision.

Primary example: Generac current 10-26 kW air-cooled owner manual.

Essential-load backup vs whole-home integration

This decision can matter more than the logo on the enclosure.

Essential-load system

An essential-load architecture intentionally protects selected circuits or equipment. Typical candidates can include refrigeration, selected lights/receptacles, a fuel-burning furnace’s controls and blower, sump equipment, a well pump, and communications gear.

The advantage is obvious: if you refuse to back up discretionary heavy loads, you may need substantially less generator capacity.

Whole-home or whole-service system

A whole-home architecture connects the backup source broadly enough that much or all of the home’s distribution remains available during an outage. The generator still has a finite continuous and motor-starting capability.

Large loads can therefore be:

• shed automatically,
• locked out while on generator power,
• staged so they do not start together,
• or left for the homeowner to defer.

Generac’s current Canadian RXSW200A3CUL 200 A service-entrance switch includes management for four HVAC loads. Its documentation explicitly says this can reduce the generator size needed to protect the home. Current Cummins residential literature similarly describes load management that automatically cycles high-demand devices to prevent overload. That is why whole-home connection is not the same thing as unlimited simultaneous power.

Primary sources: Generac Canadian 200 A service-entrance ATS and Cummins QuietConnect residential generator literature.

For transfer-switch types, backfeed prevention, and the electrical-work boundary, use the generator transfer-switch guide.

What size standby generator do you need?

Start with the electrical loads, not the building dimensions.

A large gas-heated urban house with municipal water may have a lower outage load than a much smaller all-electric rural house with a 240 V well pump, sump equipment, cold-climate heat pump, resistance backup heat, electric water heating, and an EV charger.

Likewise, a 200 A service does not mean you need a 48 kW generator. Two hundred amps at 240 V describes the service equipment’s capacity, not the amount of backup power your household will necessarily demand at one moment.

The sizing workflow is:

1. Decide which loads must remain available.
2. Identify which of them can operate at the same time.
3. Verify 120/240 V requirements.
4. Verify motor/compressor starting demand using the actual equipment data.
5. Decide what can be deferred or automatically shed.
6. Compare the resulting requirement with the generator’s continuous rating on your actual fuel.

Do not use a square-foot rule

Rules like “14 kW below 2,500 square feet” are sales shortcuts, not electrical load calculations. Square footage cannot tell you whether the house has a well pump, auxiliary electric heat, two AC compressors, gas appliances, or an EV charger.

HVAC can dominate the answer

Central AC, heat pumps, inverter-driven compressors, soft starters, and auxiliary resistance heat can produce wildly different generator requirements. A heat pump’s electric backup strips can be a much larger sustained load than its compressor.

ReadyHome’s generator size calculator intentionally refuses to fake exact AC/heat-pump numbers when equipment-specific data are needed. Keep that behaviour. A confident wrong answer is not a feature.

Load management can be cheaper than more generator

Automatic load management lets the system keep selected large loads from stacking together.

Current Canadian Generac transfer equipment can manage HVAC loads directly, with additional external load-management hardware available for other loads. Cummins likewise advertises intelligent load management for current residential systems.

Possible candidates for management include:

• central air conditioning,
• heat pumps,
• electric water heaters,
• electric dryers,
• ranges/ovens,
• hot tubs,
• and EV charging.

Exactly what can be controlled depends on the equipment and the proposed design. Ask the installer to identify every managed load, its priority, what triggers shedding, and what happens if the control hardware fails.

Natural gas vs propane standby generators

Neither fuel wins everywhere.

The headline kW number may not apply on natural gas

Fuel-specific ratings are not a rounding error.

Two current examples:

The Generac 26 kW specification also lists natural-gas consumption of 188 CFH at half load and 333 CFH at full load, while the current Rehlko 26RCA sheet lists 180 CFH at 50% and 290 CFH at 100%. Even two superficially similar 26 kW machines do not share one fuel curve.

Primary sources: Generac 26 kW specification and Rehlko/Kohler 26RCA specification G4-315.

For outage fuel calculations, use the generator runtime & fuel calculator with the exact manufacturer’s data.

Natural-gas service capacity is part of the project

Do not assume the existing meter or gas piping can feed a large generator just because the house already has natural gas.

FortisBC’s current service guidance says that when a new appliance materially increases gas use and a different regulator or larger meter may be needed, the gas fitter supplies the required delivery pressure and total connected BTU load and FortisBC determines the service needs.

That total load can include the generator plus the furnace, water heater, fireplace, range, pool equipment, and other gas appliances that may operate at the same time.

A useful reality check: the current Generac 26 kW unit alone publishes 333 CFH at full natural-gas load. That does not tell you what meter you need. It tells you why “the meter is probably fine” is not engineering.

Primary source: FortisBC: upgrade your natural-gas service.

Propane tank sizing is a cold-weather problem too

A tank can contain plenty of propane by volume and still fail to vaporize it quickly enough for a large engine in deep cold.

Propane vaporization depends on at least:

• tank dimensions,
• liquid level / wetted surface,
• outdoor temperature,
• generator fuel demand,
• other propane appliances,
• and whether the tank is above or below ground.

RegO’s current engineering catalog makes the temperature effect painfully clear. Its vaporization method applies different multipliers as outdoor temperature falls and warns that underground-container sizing also depends on frost penetration.

That is why ReadyHome does not publish a rule such as “every 22 kW generator needs a 500-gallon tank,” and it does not assume a fixed percentage of nominal tank volume is usable in every Canadian winter.

Engineering reference: RegO 2024 LPG catalog and vaporization method.

Canadian winter changes the installation

Winter readiness is model-specific, not a universal “cold-weather kit” checkbox.

Current Generac documentation, for example, describes a breather heater for specified air-cooled models in extreme icing conditions. Its current support guidance also ties oil requirements to the exact model and maintenance situation. Other manufacturers package cold-weather equipment differently.

Ask about:

• approved oil for the exact model and temperature range,
• starting-battery cold performance,
• battery/oil/breather heating accessories where specified,
• snow and drifting around cooling and combustion-air openings,
• freezing rain,
• service access after a storm,
• and whether the proposed mounting location sits in a plow or roof-shedding path.

Never build an improvised box or shelter around a standby generator unless the manufacturer specifically approves the configuration. Cooling and exhaust airflow are part of the machine’s design.

Manufacturer example: Generac breather-warmer guidance.

Placement and carbon monoxide: do not copy portable-generator clearances

This one deserves care because two valid pieces of guidance can look contradictory.

Health Canada tells Canadians to operate portable fuel-burning generators at least 6 m (20 ft) from buildings and direct exhaust away from openings. That is excellent portable-generator advice.

Permanently installed standby generators are different listed appliances with model-specific installation instructions. A current Generac air-cooled installation guide, for example, permits 18 in (457 mm) rear clearance in a qualifying installation while prohibiting operable windows, doors, or openings within 5 ft (1.52 m) of the generator and requiring additional front/end/overhead clearance. Rehlko’s current 26RCA sheet likewise says the enclosure meets NFPA guidance for 18 in placement, while telling installers to check local codes.

So there is no responsible single Canadian standby-generator clearance to copy into every project.

Your actual site must satisfy the exact generator instructions plus applicable gas, electrical, fire/building, zoning, property-line, and local authority requirements.

Sources: Health Canada CO guidance, Generac air-cooled installation guidance, and the exact installation manual supplied with the proposed generator.

Exercise and maintenance: automatic is not maintenance-free

Exercise schedules and test depth vary by controller.

The current Generac 26 kW specification lists a five-minute exercise and selectable weekly, bi-weekly, or monthly scheduling. Rehlko’s current 26RCA specification offers several modes, including a short unloaded EcoExercise, longer unloaded exercises, and a loaded exercise when paired with compatible transfer equipment. It also supports weekly, bi-weekly, or monthly intervals.

That proves two useful things:

1. Not every standby generator exercises weekly.
2. An unloaded exercise is not the same test as carrying the house.

A successful unloaded exercise confirms some pieces of the chain. It does not prove the generator will accept the real outage load, that the fuel system will maintain pressure at full demand, or that every managed load will behave correctly.

Multi-day outages still require attention

For current Generac 10-28 kW air-cooled systems, Generac says continuous-use maintenance is needed every 24 hours: shut the unit down safely, inspect it, and check oil and other conditions. Service intervals then depend on accumulated hours and environment. That is Generac-specific guidance, not a universal schedule for every standby generator.

Battery maintenance is also real. Generac currently describes a typical starting-battery life of roughly 3-5 years, while its maintenance documentation focuses on inspection and condition rather than a universal mandatory two-year replacement.

The manual for the exact generator wins.

Primary sources: Generac continuous-use maintenance, Generac maintenance schedule, and Rehlko 26RCA specification.

What does a standby generator cost in Canada?

There is no honest national average without defining the scope.

Current Canadian published examples show why:

Those are dated market examples, not a Canadian average. Different quotes can include different generator hardware, ATS equipment, trenching, gas work, load-management hardware, permit fees, cold-weather accessories, site restoration, and utility upgrades.

Current examples: Home Depot Montréal generator installation and Huntley Electrical Chilliwack pricing.

What a quote should itemize

At minimum, ask whether the price includes:

• exact generator model and fuel rating,
• exact transfer switch and service rating,
• electrical labour/materials,
• fuel-gas work,
• gas meter/regulator/service changes,
• propane tank/regulator work where applicable,
• pad/site preparation,
• trenching and restoration,
• load-management modules,
• cold-weather accessories,
• permits and inspections,
• commissioning and homeowner handoff,
• starting battery,
• remote-monitoring subscription if any,
• and first maintenance/service visit.

Canadian permits and qualified trades

There is no one national permit workflow.

A few current examples show the pattern:

• British Columbia: Technical Safety BC says gas-fired stationary generators in its jurisdiction must be listed as appliances on a gas installation permit, and approved/certified equipment is required. Local governments can have separate jurisdiction. TSBC stationary-generator permit bulletin.
• Ontario: ESA says a notification of work must be filed to connect a generator permanently to a home’s electrical system and strongly recommends a Licensed Electrical Contractor. ESA generator safety.
• Alberta: the Safety Codes Act framework applies to electrical and gas work, and Alberta currently has the 2024 Canadian Electrical Code in force plus current B149 gas codes. Alberta electrical codes and Alberta gas codes.

Canadian context

Do not assume the installer automatically handles every permit, utility approval, or inspection. Ask for the permit numbers, authority having jurisdiction, inspections included, and any work explicitly delegated to another contractor.

Ten questions to ask before comparing installer quotes

1. What is the exact generator model and its continuous rating on my chosen fuel?
2. What actual household loads did you use to size it, and which startup loads need exact equipment data?
3. Is this selected-circuit backup or whole-home/whole-service integration?
4. Which loads are automatically shed or locked out, in what priority, and what happens if load-management hardware fails?
5. What exact transfer switch are you proposing, and is it service-entrance rated where the design requires that?
6. Has a qualified gas professional verified total connected fuel demand, delivery pressure, meter/regulator capacity, and the proposed fuel run?
7. What exact manufacturer and local siting rules apply at the proposed location, including openings, air intakes, service access, snow, and property lines?
8. Which cold-weather accessories does the exact model require or recommend for this climate?
9. Which electrical, gas, municipal, and utility permits/inspections are included in the contract?
10. What is excluded from the quote, and what site condition would legitimately increase the price later?

If two quotes use different generator sizes, do not compare only the kW and price. Compare the fuel-specific rating, protected loads, load-management plan, transfer architecture, fuel-system scope, permits, winter accessories, and excluded work.

Is a standby generator worth it?

It can be, but the answer depends on the consequence of losing power rather than on the house being “big enough.”

A standby system gets easier to justify when outages can stop systems that are expensive or dangerous to leave down, such as:

• private-well water,
• sump/dewatering equipment,
• fuel-burning heating controls during winter,
• refrigeration/freezers,
• accessibility or medical-adjacent equipment,
• or a home that is frequently vacant during storm season.

It is harder to justify when outages are rare, short, and a portable generator or battery can cover the meaningful loads safely at much lower cost.

Standby generator + home battery

A supported hybrid can be excellent: the battery can handle short outages and quiet low-load periods, while a generator can extend endurance and, in compatible systems, recharge storage.

But integration is product-specific. Do not assume any standby generator can connect to any battery inverter because both say 120/240 V. Controls must coordinate islanding, generator start/stop, charging, solar behaviour, and protection.

Generac’s current home-energy literature, for example, describes supported PWRcell 2 plus home-standby integration where the generator can start as battery energy falls and power the home while recharging the battery. That proves the architecture exists; it does not make arbitrary cross-brand combinations compatible.

For the battery side of the decision, use Home Battery Backup Canada.

Frequently asked questions

What size standby generator do I need?

Size the loads that must run together, then account for motor/compressor starting demand, voltage requirements, and the loads you can shed or defer. Do not size from square footage or main-service amperage alone. Use the generator size calculator and replace presets with actual equipment data before buying.

What is the difference between a standby generator and a whole-house generator?

“Standby generator” describes the permanently installed automatic generator category. “Whole-house” or “whole-home” usually describes broad electrical integration. A whole-home-connected system can still have load limits and automatic shedding.

How much does a whole-house generator cost in Canada?

Published Canadian 2026 examples span well into five figures, but scope varies too much for one honest national number. Compare quotes by generator/ATS hardware, electrical work, gas work, site preparation, trenching, load management, permits, cold-weather equipment, and utility upgrades.

Does a 200 A service need a 48 kW generator?

No. The service rating is not the same as the desired outage load. A 200 A service can be paired with a much smaller generator when the actual backup loads and load-management design support it.

Is natural gas or propane better for a standby generator?

Neither universally. Natural gas avoids on-site refilling while utility service is available; propane provides on-site stored fuel. Natural gas requires service-capacity verification, while propane requires storage/refill and cold-weather vaporization planning. Use the generator’s exact rating on the chosen fuel.

What is the best standby generator in Canada?

There is no responsible universal winner. Compare the exact model’s usable output on your fuel, starting capability, compatible transfer/load-management hardware, cold-weather support, documentation, Canadian approval, service network, warranty, fuel consumption, and installed-system price. Headline kW alone is a lousy ranking method.

Can a standby generator run forever during an outage?

No. Fuel availability is only one constraint. Engines have inspection and maintenance requirements, faults can occur, snow or debris can obstruct the unit, and propane storage is finite. Current Generac air-cooled guidance, for example, requires daily continuous-use maintenance after each 24 hours of operation.

Methodology and research limits

Methodology

This guide was built from fresh Canadian keyword research, current Canadian safety/regulatory sources, current manufacturer manuals/specification sheets, and dated Canadian installation-price examples. Chris Gaglardi receives research/methodology credit; he is not presented as an electrician, gas fitter, generator technician, or engineer.

Primary-source verification materially changed the supplied deep-research dossier before publication. We rejected universal propane-tank minimums, a national “250 CFH meter” assumption, universal standby clearances, a mandatory two-to-three-year battery replacement rule, and several model-table fuel/starting figures that did not match current manufacturer sheets. Product specifications, codes, programs, and prices change. Verify the exact model and current authority requirements before purchase or installation.

The governing idea is the same from the first load calculation to the final quote:

Do not buy a standby generator by house size or headline kW. Design the backup system around the loads, fuel, transfer architecture, load management, climate, and outage duration that actually matter.