Residential Service Sizing Guide (Canada)
Service size follows from load calculation—not breaker count alone. After Rule 8-200 gives you watts, divide by voltage to get amps and select the next standard rating. Use our residential load calculator to run the numbers live.
100A service
100 A at 240 V equals 24,000 W—the Rule 8-200(1)(b) minimum for many dwellings. Adequate for smaller homes without major electrification loads.
125A and 200A
125 A is a utility-specific intermediate rating. 200 A (48,000 W) is the common upgrade for EV charging, heat pumps, and suites. Most new Canadian construction targets 200 A when electrification is planned.
400A and larger
Large estates, combined dwelling scenarios, or heavy workshop loads may require 400 A or parallel services. Coordinate with the utility early.