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Size Backup Power in August, Not During the January Outage

Most generator enquiries arrive during an outage, the worst possible time to decide. How to size one honestly, and why the transfer switch matters more.

Published
July 28, 2026

Every generator enquiry we get in January starts the same way, and it is the worst possible moment to be making the decision: the power is out, it is cold, the sump pit is filling, and whatever is available that week is what gets bought.

Late summer is when this should be decided. The equipment is available, the work can be scheduled properly rather than squeezed in, and you have time to size it around what you actually need instead of what is in stock.

Start with the circuits, not the generator

The mistake is shopping for a generator first. The right order is to decide which circuits genuinely have to stay live, then size the generator to those.

For a Barrie house in a winter outage, that list is usually shorter than people expect:

  • The furnace. Gas furnaces still need electricity for the blower, the igniter and the controls. Without power you have no heat regardless of the fuel.
  • The sump pump. In this city, storms and thaws are exactly when a sump pit is working hardest, and exactly when the power is most likely to be out. This one is not optional if you have a pit.
  • The refrigerator, and the freezer if you keep one.
  • A well pump, if you are on a well, which covers a lot of Oro-Medonte and Springwater.
  • Some lighting and a few outlets. Not every outlet in the house.

That is a modest load. It is nothing like the whole-home system that gets quoted when someone asks for “a generator” without qualifying it.

The transfer switch is the actual job

The generator is the part people shop for. The transfer switch is the part that matters, and it is where the electrical work is.

A transfer switch isolates your selected circuits from the incoming utility service before connecting them to the generator. It exists so that your generator cannot push power back out onto the utility lines, which is a serious hazard to anyone working on those lines, and a real one, not a theoretical one.

Running a generator into the house by back-feeding a dryer receptacle with a double-male cord does exactly what a transfer switch prevents. It is not a shortcut with a small risk attached; it is the specific thing the equipment exists to stop.

Manual or automatic

Manual. You start the generator, throw the switch, and the selected circuits run. Cheapest by a wide margin, entirely adequate if someone is home, and the right answer for most households.

Automatic standby. Detects the outage, starts itself, transfers over, and shuts down when utility power returns. Worth it if the property is regularly unoccupied, if there is a medical dependency, or if a sump failure would flood a finished basement while nobody is there.

The timing argument

Everything about this is easier in August. Equipment is in stock. The permit and inspection happen on a normal schedule. You can size the thing by walking the house with someone rather than by guessing over the phone in the dark.

The households that get through a Simcoe County ice storm comfortably are, without exception, the ones that sorted it out in the summer.

FAQ

Related questions

Do I need a whole-home generator?

Most Barrie households do not. The circuits that actually matter in a winter outage are the furnace, the sump pump, the fridge, a well pump if you have one, and some lighting and outlets. A correctly wired transfer switch covering those costs a fraction of a whole-home system.

Can I just run extension cords from a portable generator?

For a fridge on a covered porch, people do. For a furnace or a sump pump, no. Those are hardwired loads, and back-feeding a house through a dryer outlet is both illegal and genuinely dangerous to line workers. That is what a transfer switch exists to prevent.

How long does a transfer switch install take?

A manual transfer switch serving a defined set of circuits is usually a single day, done under permit. An automatic standby unit involves a concrete pad, a fuel connection and more coordination, so it is scheduled work rather than something to arrange in a week.

Talk to a Barrie electrician

Describe what the panel is doing over the phone. We can usually tell you whether it needs a truck today or can wait for a scheduled visit — and roughly what it costs — before anyone books anything.

(249) 800-0317

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