What is the difference between 100 amp and 200 amp service?

The main difference between 100 amp and 200 amp electrical service is the total amount of power your home can safely use at one time. A 100 amp service provides 24,000 watts of power (100 amps × 240 volts), while a 200 amp service delivers 48,000 watts - exactly double the capacity.

Practical Differences in Your Home

With 100 amp service, you might experience breaker trips when running multiple high-demand appliances simultaneously - like your electric dryer, air conditioning, electric water heater, and oven all at once. A 200 amp service eliminates this problem by providing much more electrical headroom. This extra capacity becomes crucial when adding modern electrical loads like EV chargers (typically requiring a dedicated 40-50 amp circuit), hot tubs (30-50 amps), or whole-home generators.

The physical differences are also significant. A 100 amp panel typically has 20-24 circuit breaker spaces, while 200 amp panels usually offer 40-42 spaces. This means more circuits for dedicated appliances, additional outlets, and future electrical needs. The main electrical cables feeding your home are also larger with 200 amp service - typically 4/0 AWG copper or 250 MCM aluminum versus 2/0 AWG for 100 amp service.

When You Need to Upgrade

In Ottawa's housing market, most homes built before 1980 have 100 amp service, which was adequate for the electrical demands of that era. However, modern homes typically require 200 amp service due to increased electrical loads from central air conditioning, multiple large appliances, home offices with computer equipment, and electric vehicle charging. The Ontario Electrical Safety Code requires 200 amp minimum service for new home construction.

If you're planning to install an EV charger, the math becomes important. A typical Level 2 EV charger draws 32-40 amps continuously. On a 100 amp service, this represents 30-40% of your total capacity, leaving little room for other appliances. Most electricians recommend upgrading to 200 amp service before installing EV charging equipment.

Upgrade Costs and Process

In Ottawa, upgrading from 100 amp to 200 amp service typically costs $2,000 to $3,500, depending on the complexity of your installation and whether the main electrical cables from the street need replacement. This work requires an ESA permit and inspection, and must be performed by a licensed electrician. Hydro Ottawa may need to upgrade the transformer and meter base, which they handle at no charge to you.

The upgrade process involves installing a new 200 amp panel, upgrading the main electrical cables if necessary, and having ESA inspect the work. Most upgrades are completed in one day, though you'll experience a power outage of several hours during the installation.

For a free assessment of whether your home needs a service upgrade, Electrical Ottawa provides consultations to help Ottawa homeowners understand their electrical capacity needs and upgrade options.

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