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Electrical Service Capacity Calculator Ontario (2026): Will a Heat Pump, EV Charger, Induction Range or Hot Tub Fit on Your 100 or 200 Amp Service? The Rule 8-200 Arithmetic, Step by Step
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Will It Fit on Your Panel? Run the Same Arithmetic the Electrician Runs.
The single-dwelling load calculation from the Ontario Electrical Safety Code, Rule 8-200, for your house and the things you want to add. No email address required.
A full panel is not a full service. A parking lot with no empty stalls can still have a quiet road out front. Whether a heat pump, an EV charger or an induction range fits is not decided by the spaces in the panel or by a salesman’s rule of thumb; it is decided by a calculation in the electrical code that gives each kind of load its own weight. This page runs that calculation so you know the answer before anyone quotes you a $4,000 upgrade.
Step-by-step
Service Capacity, Rule 8-200 (Ontario)
1
The house and the service
Outside dimensions of every floor from the main floor up.
Counts at 75 percent, finished or not. Enter 0 for a slab or crawlspace.
The number on the main breaker. If you are building new, pick what you are planning.
2
Heating and cooling
Baseboards, electric furnace or boiler, heat pump backup strips, electric floor heat. 0 if you heat with gas, propane or oil.
The nameplate: amps x 240 / 1000. A typical 3 ton unit is about 3 to 4.5 kW.
3
Kitchen, laundry and hot water
The nameplate rating. 0 for a gas range. Most are 10 to 14 kW.
0 for gas. Most are 5 to 5.6 kW.
Tankless heaters count at 100 percent; tanks at 25 percent with a range.
4
What you are adding
Each one counts at 100 percent unless a load manager limits it.
Spa and pool heaters count at 100 percent. A typical hot tub heater is 4 to 6 kW.
Workshop, sauna, second oven, well pump over 1.5 kW. Smaller loads are already in the basic allowance.
5
Where is the house?
Sets the installed-price adjustment. Labour rates in the GTA run higher than in the rest of the province.
Used only to tell you whether the house is in our direct service area. Not stored.
Enter a postal code to see service coverage.
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Calculated Load, Rule 8-200
Planning estimate
| Line | Watts |
|---|
Calculated load–
Planning estimate using the single-dwelling method of Rule 8-200 as ESA describes it: a basic load of 5,000 W for the first 90 m2 of living area and 1,000 W for each further 90 m2 or part of it (basement over 1.8 m at 75 percent); electric space heat at 100 percent of the first 10 kW and 75 percent of the rest; air conditioning at 100 percent; a range at 6,000 W plus 40 percent over 12 kW; tankless, spa and pool heaters and EV chargers at 100 percent; other loads over 1,500 W at 25 percent with a range (without one, 100 percent of the first 6,000 W and 25 percent of the rest); never less than 24,000 W (100 A) for 80 m2 or more above ground. Amps = watts / 240 V. An LEC may also use measured demand on an existing service (Rule 8-106). Not a design.
Request a Real Quotation
Your loads, your service and the calculated amps become a written scope a Licensed Electrical Contractor can quote: a load manager, a service upgrade, or nothing at all. It goes straight to our inbox, and a copy comes back to you; reply to that copy with photos of the panel with the door open, the label inside the door and the meter.
How the code adds up a house
The code does not add every nameplate together, because nobody runs the range, the dryer, the oven, the hot tub and the charger flat out at the same minute. It gives each kind of load a weight. Heat and air conditioning count almost in full because they run for hours. A range counts as 6,000 W no matter how big the box says, up to 12 kW. A dryer or a water tank counts a quarter when there is a range. An EV charger counts in full, because it runs for hours at night, unless a load manager limits it.
| Load | How it counts |
|---|---|
| Basic allowance (lights, receptacles, small appliances) | 5,000 W for the first 90 m2 of living area, 1,000 W for each further 90 m2 or part |
| Electric space heat | 100% of the first 10 kW, 75% of the rest |
| Air conditioning or heat pump | 100% (if heat and AC are interlocked, only the larger) |
| Range | 6,000 W, plus 40% of the rating over 12 kW |
| Tankless water heater, hot tub, pool heater | 100% |
| EV charger | 100%, unless an energy management system limits it |
| Other loads over 1,500 W (dryer, water tank, shop) | 25% with a range; without one, 100% of the first 6,000 W and 25% of the rest |
| Minimum | 24,000 W (100 A) for a house of 80 m2 or more above ground |
The single-dwelling method of Rule 8-200 in the 2024 Ontario Electrical Safety Code, in plain words. ESA’s own worked example: a 140 m2 house with air conditioning, a 12 kW range, a 32 A Level 2 charger (7,680 W at 100%), a dryer and an electric water tank came to 26,055 W, 108.6 A, needing at least a 125 A service.
Three houses, worked out
| House | The arithmetic | Result |
|---|---|---|
| 1,200 sq ft bungalow, 1,200 sq ft basement, gas heat, 3 kW AC, 12 kW range, 5 kW dryer, adding a 32 A charger | Area 111 + 0.75 x 111 = 195 m2; basic 7,000; AC 3,000; range 6,000; charger 7,680; dryer 25% = 1,250; total 24,930 W | 104 A: over 100 A. With a load manager the house calculates at 17,250 W, under the 24,000 W minimum, so it fits on 100 A |
| 2,000 sq ft two-storey, 1,000 sq ft basement, all electric: 4 kW heat pump, 10 kW strips, 12 kW induction, 5 kW dryer, 4.5 kW heat pump water heater, 40 A charger | Area 256 m2; basic 7,000; strips 10,000; heat pump 4,000; range 6,000; charger 9,600; dryer and water heater 25% of 9,500 = 2,375; total 38,975 W | 162 A: a 200 A service |
| The same house in leaky 1980s frame with 20 kW of baseboards and no heat pump | Basic 7,000; heat 10,000 + 75% of 10,000 = 17,500; range 6,000; charger 9,600; others 2,375; total 42,475 W | 177 A: still 200 A, with less room left |
Areas converted at 10.764 sq ft per m2 and rounded. Planning arithmetic, not a design; the electrician’s calculation is the one that counts.
Where homeowners go wrong
- Counting breakers. Adding up the numbers on the breakers gives you three or four times the real load. The code calculation is the test.
- Upgrading for a charger that a load manager would handle. About $1,000 against $2,500 to $5,000. EV on 100 A.
- Buying a subpanel to fix a capacity problem. It adds spaces, not amps. Subpanel or upgrade.
- Sizing electric heat from square feet. The heat loss sets the kW. A tight house needs far less.
- Forgetting the hot tub. A spa heater counts in full; it is often the load that tips a 100 A house over. The 100 or 200 amp page covers the bigger decision.
Questions people ask
Is 100 amp service enough for a house in Ontario?
Often yes for a gas-heated house, even with an EV charger on a load manager. Add electric heat, a heat pump with strips, an induction range and a hot tub and it usually is not. Run the calculation with your own loads.
Can I put an EV charger on a 100 amp panel?
In many houses, yes, with a load manager that limits the charger when the house is busy, or at a lower charging current. The calculation above shows which. EV charger cost.
Does a heat pump need a 200 amp service?
Not by itself. A 3 ton heat pump is about 3 to 4.5 kW. The electric backup strips are the big part: 10 kW of strips add 10,000 W to the calculation.
Who decides if my service is big enough?
The Licensed Electrical Contractor who files the ESA notification does the calculation, and ESA inspects it. On an existing service the contractor may also use your measured demand from the utility’s meter data.
What does upgrading to 200 amps cost in Ontario?
About $2,500 to $5,000 overhead and $5,000 to $7,000 and up underground with a trench, October 2026, before HST. Panel upgrade cost.
Been told you need an upgrade?
The $99 quote review reads your quotes and your panel photos against this calculation and tells you whether an upgrade, a load manager or nothing is the answer.
