Do I Need a 400-Amp Electrical Service for My House?

Two hundred amps is the modern standard for a single-family home in Ontario. So when does a homeowner actually need a 400-amp service? The answer is not as often as social media makes it sound, but it is more common than it used to be as heat pumps, EV chargers, and induction ranges start stacking up. This guide covers when a 400-amp upgrade is warranted in a Toronto or GTA home, when 200 amps is still enough, and what the upgrade actually involves.

Do I need a 400-amp electrical service for my house?

Most Ontario single-family homes do not need 400 amps. A properly sized 200-amp service comfortably supports central AC, a Level 2 EV charger, an electric range, and a heat pump conversion. A 400-amp service is warranted when a formal load calculation exceeds what a 200-amp service can safely carry — typically in large custom homes, homes with two EV chargers, homes with hot tub plus pool plus heat pump, or larger detached properties with electric heat plus a workshop. Do the load calc first; do not upgrade to 400 amps because it “sounds future-proof.”

For the calc itself, see how to calculate my home’s electrical load capacity.

What each service size actually delivers

• 100-amp service: Common in GTA homes built 1970s–2000s. Delivers up to 24,000 W at 240V. Increasingly tight for modern loads.
• 200-amp service: Modern residential standard. Delivers up to 48,000 W at 240V. Comfortable for most GTA homes including EV, central AC, heat pump conversion, and induction range combinations.
• 400-amp service: Delivers up to 96,000 W at 240V. Typically implemented as two 200-amp panels or a large 400-amp panel. Warranted for larger custom homes or homes with genuinely heavy load stacking.

When a 400-amp service is actually justified

• Load calculation exceeds 200 amps (the mathematical trigger).
• Two or more Level 2 EV chargers running simultaneously.
• All-electric heating (heat pump plus electric backup) combined with electric range, water heater, and EV charging.
• Pool heater plus hot tub plus heat pump combined with normal residential loads.
• Homes over roughly 4,000 sq ft with heavy electric appliance load.
• Detached workshop or coach house with its own dedicated subpanel plus significant tool load.
• Homes with commercial-grade equipment or a home business with equipment beyond typical residential.

If none of the above apply, 200 amps is almost certainly enough. A properly designed 200-amp service can accommodate an aggressive electrification path for most homes.

When 200 amps is enough (and 400 would be overkill)

• Single-family home under 3,500 sq ft with typical modern appliance mix.
• One EV charger, central AC, gas or heat-pump heat, standard range.
• No hot tub, pool heater, or workshop equipment.
• Load calc comes back under 160–170 amps.
• Grid connection and utility service cost make 400 amps significantly more expensive than 200.

Load-managed EV chargers (which curtail during peak home load) can help stretch a 200-amp service further, sometimes eliminating the need for an upgrade. See can I install my own EV charger.

What a 400-amp service upgrade involves in the GTA

1. Load calculation and design by an ECRA/ESA-licensed contractor.
2. Utility coordination. The local utility (Alectra, Toronto Hydro, Hydro One) must confirm the local transformer and service feed can supply 400 amps, and quote any upgrade cost on their side.
3. New service entrance conductors from the meter to the new panel(s).
4. New 400-amp meter socket.
5. Panel arrangement. Usually either one 400-amp main disconnect feeding two 200-amp subpanels, or a single 400-amp panel with high-capacity bus.
6. Grounding and bonding upgrade to match the larger service.
7. ESA notification, inspection, and Certificate of Inspection per the Ontario Electrical Safety Code.

Timeline is typically 2–4 days on site plus utility coordination time. See how long does an electrical panel upgrade take.

Cost implications (GTA rough ranges)

• 100- to 200-amp upgrade: commonly $4,000–$8,000 CAD in the GTA for straightforward jobs, more if service mast or utility side work is needed.
• 200- to 400-amp upgrade: commonly $10,000–$25,000+ CAD depending on utility upgrade costs, panel configuration, and civil work.
• Utility-side charges for a transformer or service-drop upgrade can add significantly to the total.
• Load management devices that let a 200-amp service handle more can cost $1,500–$3,000 CAD installed and often eliminate the need for a 400-amp upgrade.

Costs vary significantly by property, and any specific quote should come from a licensed contractor after a site visit.

Alternatives to a 400-amp upgrade

• EV load management. Smart chargers that curtail during home peaks.
• Sequencing large loads. Sharing dedicated circuits between the range and the oven, or the EV charger and the dryer, using approved lockout devices.
• Right-sizing the heat pump. An over-specced heat pump can push load unnecessarily.
• Time-of-use scheduling. Running the pool heater and EV charger overnight when other loads are lower.
• Subpanel with load-shedding controller. Prioritizes critical loads during peak.

Any of these can extend a 200-amp service well past what a naive load calc suggests, sometimes for a fraction of the cost of a 400-amp upgrade.

When to actually plan for 400 amps

• You are building a custom home over 4,000–5,000 sq ft with all-electric appliances and heat.
• You are renovating a large heritage home and going all-electric while keeping the character wiring in the rest.
• You have a workshop, coach house, or garage with heavy equipment.
• You are planning two EV chargers for a two-vehicle household with both drivers charging simultaneously.
• Your load calc comes back at or above 200 amps with no realistic load management options.

Expert tip from our ESA-licensed electricians

In our GTA field data, roughly one in twenty homes we quote for a 100-to-larger upgrade actually needs 400 amps. The other nineteen are fine on a properly designed 200-amp service, sometimes with a $500 load-management device to keep the EV in check during peak dryer runs. If a contractor recommends a 400-amp service without first running a formal load calc and discussing load management options, get a second opinion. Over-sizing the service is not dangerous, but it can add ten thousand dollars to a project that did not need it. The load calc is a one-hour exercise that saves that money nine times out of twenty.

Related reading from ezsmart.ca

• How to Calculate My Home’s Electrical Load Capacity
• How Long Does an Electrical Panel Upgrade Take?
• Can I Install My Own EV Charger?
• What Is a Subpanel and When Do I Need One?
• How to Tell If an Electrical Panel Is Overloaded

Contact us

Not sure if your Toronto or GTA home needs a 200- or 400-amp service? Call ezsmart at 416-838-9006 or use our contact page. An ESA-licensed electrician will run the load calc, discuss load-management options, and quote the right-sized upgrade.