Nearly everybody asking this question has already been told the answer by somebody with something to sell.
So here is the version with the arithmetic in it.
What the code actually requires
The Ontario Electrical Safety Code sets a minimum service size for a single dwelling, and it is tied to floor area rather than to what you own.
Once the floor area of the dwelling, not counting the basement, reaches 80 square metres — about 861 square feet — the minimum permitted service is 100 A. Below that area, the code permits 60 A.
Read that carefully, because it is routinely misquoted in both directions. It does not say 100 A is adequate for your house. It says nobody may install less. A floor is not an assessment.
Which is why the real question is a calculation
The service has to carry the connected load, and that is worked out rather than eyeballed. Floor area gives a basic load. Then the range, the water heater, any electric heat, the air conditioning, the dryer and any additional loads are added, each with the demand factor the code assigns it.
The answer comes out in amps. It is either under 100 or it is not.
How do I know if my electrical service is big enough?
You have it calculated once, properly, and then you know for a decade. It takes a competent contractor under an hour with the panel schedule and a walk through the house, and it is the difference between a four-thousand-dollar decision made on evidence and one made on a hunch.
What genuinely eats a 100 A service
Not lighting. Not receptacles. Not the things people worry about.
| Load | Appetite | Notes |
|---|---|---|
| Electric baseboard or furnace heat | Very large | The single biggest driver in this region |
| Level 2 EV charger | Large | Counted as a continuous load at 125 percent of its rating |
| Electric range | Large | Gas or propane changes the answer entirely |
| Electric water heater | Large | Common on rural properties with no gas |
| Heat pump | Moderate to large | Depends on backup heat strategy |
| Hot tub | Moderate | Frequently the load that tips it over |
One of these on a 100 A service is usually fine. Three is usually not. That is the whole shape of it.
The charger is the modern trigger
More service upgrades get booked because of a car than for any other reason now, and a good share of them are not needed. A level 2 charger counts as a continuous load at 125 percent of its rating, which is why it takes more room in the calculation than its nameplate suggests, and why the charger question deserves its own working.
An energy management system that sheds the charger when the range or the dryer is running is the alternative, and on a house that is otherwise comfortable at 100 A it is dramatically cheaper than the upgrade.
A full panel is not a full service
This one costs people real money, so it is worth separating properly.
Spaces are physical slots for breakers in the panel enclosure. Capacity is how much current the service conductors and the main can carry. They have nothing to do with each other.
A panel with no spaces left, on a service with plenty of headroom, is a subpanel job. A service running near its calculated limit, behind a panel with four empty spaces, needs an upgrade regardless of how roomy it looks.
Anyone quoting a service upgrade because the panel “is full” has answered the wrong question.
What changes the price around here
Two regional facts move the number more than the amperage does.
The ground. A grounding electrode behaves differently in thin soil over Canadian Shield rock through Bracebridge, Huntsville and Parry Sound than it does in the dry sand at Wasaga Beach or the deep organic soil of the Holland Marsh at Bradford. That is the most common reason two identical panels get quoted hundreds of dollars apart, and what a panel upgrade costs here goes through it properly.
The distributor. A service upgrade needs a disconnect, and the disconnect is scheduled by whichever of the region’s nine utilities holds your town — Hydro One in Orillia, Newmarket-Tay in Midland, Lakeland Power across Muskoka, EPCOR in Collingwood. That, not Collingwood electrical permit turnaround time, decides your calendar, not your electrician’s. The notification of work goes in before any of it.
Coming up from 60 amps is a different job
A 60 A service is not a smaller version of this decision. It is a different one.
Sixty amps with screw-in fuses, ungrounded circuits and two-prong receptacles throughout is the pre-war town stock in Orillia, Midland, Collingwood and Creemore, and it is usually an insurance conversation rather than a capacity one. The upgrade generally takes a new mast, meter base and panel rather than a panel swap, which is why it sits at the top of the range on our service page for panel upgrades.
What we will tell you not to spend money on
Do not go to 200 A because a neighbour did. The calculation is about your house and your appliances. A gas range and a gas water heater change the answer completely.
Do not upgrade to fit one charger before somebody has priced an energy management system against it.
Do not pay for a service upgrade to solve a spaces problem. A subpanel is a fraction of the cost and it is the correct fix.
And do not go past 200 A on a house without a calculation that genuinely demands it. It is rare, it is expensive, and it is usually a sign that something upstream in the specification is wrong.