On this page
Updated June 2026What is an electrical service load?
The electrical service load is the total calculated demand that a home places on the electrical utility supply. It determines the minimum size of the main service panel — 100A, 200A, or 400A. Size it too small and the main breaker trips during peak usage. Size it correctly and the panel has capacity for present and future loads.
In Canada, the electrical service load is calculated per the Canadian Electrical Code (CEC). The CEC uses a demand-based method — you do not simply add up the nameplate ratings of every appliance. Demand factors reduce the calculated load because not everything in a home runs simultaneously at full power.
CEC Rule 8-200 — the demand method
The CEC Rule 8-200 residential load calculation follows this sequence:
- Basic load (Rule 8-202): 5,000 VA for the first 90 m² of heated floor area, plus 1,000 VA for each additional 90 m² or fraction thereof
- Small appliance circuits (Rule 8-204): 1,500 VA per circuit, minimum 2 circuits (kitchen small appliance circuits)
- Combined demand factor: First 3,000 VA at 100%; remainder at 35%
- Fixed appliances: 100% of nameplate — dishwasher, garburator, freezer, etc.
- Electric range (Rule 8-208): Table 14 demand — 8 kW for ranges up to 12 kW nameplate
- Dryer (Rule 8-210): 5,000 VA or nameplate, whichever is greater
- Heating vs cooling: Use the larger of the two at 100% — never add both
Final service size = Total VA ÷ 240V, rounded up to the next standard service size.
Understanding demand factors
Demand factors exist because electrical diversity in a home is predictable. At any given moment, not every outlet is loaded, not every light is on, and not every appliance runs simultaneously. The CEC formalizes this reality into factors that reduce the paper load to a realistic peak demand.
The most significant demand factor is the 35% factor applied to general loads above 3,000 VA. This reflects that a home with 20 circuits and 40 outlets will never draw full current on all of them at once. Without this factor, a modest home would appear to need a much larger service than it actually requires.
Heating and cooling loads are treated differently — they are large, predictable, and run for sustained periods. The CEC requires the larger of heating or cooling at 100% — you never add both, since a home is not heating and cooling simultaneously.
Worked examples
Example 1 — 100 m² gas-heated home (Quebec):
- Basic load: 5,000 VA (under 90 m² threshold, but 100 m² is close — use 5,000 + 1,000 = 6,000 VA)
- Small appliance circuits (2): 3,000 VA
- Combined: 3,000 × 1.0 + 6,000 × 0.35 = 5,100 VA
- Gas range and dryer: no electric load
- Total: 5,100 VA ÷ 240V = 21.3A → 100A service adequate
Example 2 — 150 m² fully electric home (Ontario):
- Basic load: 5,000 + 1,000 = 6,000 VA
- Small appliance circuits (2): 3,000 VA
- Combined demand: 3,000 × 1.0 + 6,000 × 0.35 = 5,100 VA
- Electric dryer: 5,000 VA
- Electric range (10 kW): 8,000 VA demand
- Electric water heater (4,500W): 4,500 VA
- Electric heating (12,000W): 12,000 VA
- Total: 34,600 VA ÷ 240V = 144A → 200A service required
100A vs 200A vs 400A service
| Service Size | Capacity (VA) | Typical Application |
|---|---|---|
| 100A | 24,000 VA | Small home, gas heat and appliances, no EV charger |
| 200A | 48,000 VA | Most Canadian homes — electric appliances, 1 EV charger |
| 400A | 96,000 VA | Large homes, electric heat, multiple EV chargers, workshops |
Frequently asked questions
Do I need a 100-amp or 200-amp service in Canada?
Most homes built after 1980 have 200-amp service. If your home has electric heat, an electric range, and an electric dryer, you almost certainly need 200 amps. Older homes with all-gas appliances (gas heat, gas stove, gas dryer) may still be adequately served by 100 amps — but adding an EV charger or electric heat will typically require an upgrade.
How do I upgrade from 100-amp to 200-amp service in Canada?
A service upgrade requires a licensed electrician to replace the meter base, main breaker panel, and service entrance cable. A permit is required in all provinces. The utility must disconnect and reconnect the service — this is coordinated by your electrician. Cost typically ranges from $2,500–$5,000 depending on the province and scope of work.
Can I add an EV charger to my existing 200-amp panel?
It depends on your calculated load. A Level 2 EV charger at 32A continuous adds 4,800 VA to your calculated demand. Use this calculator to check if your existing load leaves enough headroom in your 200A service (200A × 240V = 48,000 VA capacity). Many homes with modest loads have sufficient headroom — others may need a service upgrade or load management.
Why doesn't the CEC add up all loads directly?
Because not everything in a home runs simultaneously. The CEC uses demand factors to reflect realistic peak demand. For example, the basic load gets a 35% demand factor applied to amounts over 3,000 VA, acknowledging that all outlets and lights are never fully loaded at once. This is why a 150 m² home with many circuits can still be served by a 200A panel.
What is the minimum service size for a new home in Canada?
The CEC and most provincial building codes require a minimum 100-amp service for new residential construction. However, most new homes are built with 200-amp service to accommodate modern electrical loads. In provinces like Ontario, BC, and Alberta, 200-amp service is effectively the standard for new builds.
Does electric heating require a larger service panel?
Yes. Electric baseboard heating is a major load — a typical 2,000 sq ft home with electric heat can require 15,000–25,000 watts of heating capacity. This alone may push a home from 100A to 200A or even 400A service territory. Electric heat is always included at 100% of its nameplate rating in the CEC load calculation.
How is an electric range calculated in the CEC load method?
Under CEC Rule 8-208 and Table 14, electric ranges are calculated using a demand factor rather than nameplate rating. A single range up to 12 kW is calculated at 8 kW demand. This is because ranges rarely operate all elements at full power simultaneously — the demand factor accounts for this diversity.
When do I need 400-amp service in Canada?
400-amp service is typically needed for large homes (over 400 m²), homes with multiple EV chargers, electric vehicle fleets, high-output electric heat combined with large appliances, or when a 200A panel is already at capacity with no room for future loads. It requires a larger utility transformer and higher service entrance cable costs.
Code reference
This calculator follows CEC Rule 8-200 (dwelling unit service load), Rule 8-202 (basic load), Rule 8-204 (small appliance load), Rule 8-208 and Table 14 (electric ranges), and Rule 8-210 (electric dryers). Based on CSA C22.1-21.