Before adding a heat pump, an EV charger, a hot tub or a basement suite, it helps to know whether your electrical service can carry the extra load. This calculator follows the steps of Canadian Electrical Code Rule 8-200 to estimate your home’s calculated load and the service size it needs.
Loading the Home Electrical Service Load Calculator.
How Rule 8-200 adds up a home
- Living area: 5,000 W for the first 90 m² (969 ft²), plus 1,000 W for each additional 90 m² or part of it.
- Electric range: 6,000 W, plus 40% of the rating above 12 kW.
- Water heaters, hot tub and pool heaters, steam showers and jet tubs: 100% of each rating.
- EV charger: 100% of the charge rate setting.
- Other loads over 1,500 W such as a dryer: 25% of each rating when there is an electric range; without one, the first 6,000 W in full plus 25% of the rest.
- Two dwellings: the larger at 100% and the smaller at 65%.
- Air conditioning and electric heat: 100%. If they are interlocked so they cannot run together, only the larger counts.
- Service size: the total in watts divided by 240 volts gives the amps the main service must carry.
What to do with the result
If the required amps are close to or above your existing service, a heat pump or EV charger may need a load management device or a service upgrade. This is an estimate for planning only. A permit calculation must be completed and signed by a licensed electrician who has checked the loads in your home.
Thinking about a heat pump? See heat pumps for Calgary homes, or call 587-792-1456.
Frequently asked questions
What is a service load calculation?
It adds up a home's electrical loads the way the Canadian Electrical Code allows, including a basic load for the living area, the range, water heaters, EV charging, large appliances, air conditioning and electric heat, to find the total demand the main electrical service must carry.
Do I need one before adding a heat pump, EV charger or secondary suite?
Usually yes. Adding a large load or a second dwelling unit can push the calculated load past what your existing service can carry. In Alberta, a service demand calculation must be submitted with the permit application when a secondary suite is added.
How is the required service size in amps found?
The total calculated load in watts is divided by 240 volts. This calculator rounds the result up to the next tenth of an amp so it never understates the requirement, then compares it with the service size you enter.
Why are some appliances counted at only 25%?
Under Rule 8-200, loads over 1,500 W other than the range, water heaters, EV charging and space heating or cooling are counted at 25% of their rating when the home has an electric range, because they rarely all run at once. Without an electric range, the first 6,000 W counts in full.
Can I use this result for a permit?
No. It is an estimate for planning. A permit calculation must be completed and signed by a licensed electrician who has verified the loads in the home.