Do You Need a 200 A Service for an EV Charger?

By Ryan Maxwell, Master Electrician · Updated October 28, 2026

It is the first question most Ottawa homeowners ask when they buy an electric car: is my electrical service big enough, or do I need to upgrade to 200 amps first? The honest answer is that it depends on what else your home already draws, and many homes with a 100 A service can add a Level 2 charger without an upgrade. Here is how an electrician works it out, and what your options are.

Service size and panel space are two different things

Your service is the size of the electrical supply coming into the house, set by the main breaker: commonly 100 A in older Ottawa homes and 200 A in newer ones. Your panel is the box of breakers that divides that supply into circuits.

A panel can be full (no empty slots for a new breaker) while the service still has plenty of capacity, and the reverse is also possible. A full panel can often be solved with a sub-panel or by rearranging circuits. A service with no spare capacity needs a different answer, covered below.

What a Level 2 charger needs

A Level 2 charger, including the Tesla Wall Connector, runs on a dedicated 240 V circuit. The Wall Connector can be set up for a range of breaker sizes, from small circuits up to 60 A for its full 48 A charging rate. Because a car charges for hours at a time, the code treats it as a continuous load, which is why a 48 A charger needs a 60 A circuit.

You do not have to charge at the maximum. A charger set to a lower current still refills a typical day of city driving overnight. The right setting is the one your service can support and that covers how you actually drive.

How a load calculation decides

The Ontario Electrical Safety Code sets out how to calculate a home's expected demand: a base amount for the floor area, plus the large appliances. An electrician adds up what you already have, then checks whether the charger fits within your service. The big items are:

• Electric range, oven and dryer
• Air conditioning or a heat pump
• Electric water heater or baseboard heating
• Hot tub, pool equipment or a workshop
• Any other EV charger or large future addition

A home with gas heat, a gas range and a 100 A service often has room for a modest charger. A home with electric heat, a heat pump and a hot tub on the same 100 A service usually does not.

Your options when there is no spare capacity

1. A lower charging current

Sometimes a smaller circuit is all that fits, and it is all you need. Ask yourself how far you drive on a normal day before paying for capacity you will not use.

2. An EV energy management system (EVEMS)

An EVEMS watches the total load on your service and slows or pauses charging when the house is near its limit, for example while the oven and dryer are both running, then resumes automatically. The code recognises these systems, so the charger does not have to be counted at full load. For many homes it is the difference between a one-visit install and a service upgrade. More about EV energy management.

3. A service upgrade

If you are also planning a heat pump, a hot tub or a second EV, upgrading to 200 A may be the right long-term move. It involves a new main panel, often a new meter base, and Hydro Ottawa disconnecting and reconnecting your supply, so it is planned as its own project. How panel and service upgrades work.

Permits and inspection

A new charger circuit needs an ESA notification, and the work is inspected. A licensed electrical contractor files this for you and you receive a Certificate of Acceptance when it passes. ESA permits explained.

What to send for a quick answer

Most of this can be worked out from photos before anyone visits:

• Your electrical panel with the door open, including the main breaker's label
• A list of your large electric appliances (range, dryer, air conditioner or heat pump, hot tub)
• Where you park and where you would like the charger
• Your car, or the charger you plan to buy