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

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

Most Ontario homes do not need a 400-amp service. The standard residential service is 200 amps, which is sufficient for the vast majority of homes including those with electric vehicles, heat pumps, electric ranges, and electric dryers. A 400-amp service is appropriate for large homes with very high electrical loads, homes with multiple EV chargers, homes with electric heating throughout, or properties where a substantial addition is planned.

When 200 Amps Is Usually Enough

• Single-family homes up to approximately 3,000 square feet
• Homes with one Level 2 EV charger
• Homes with gas heating and standard 240V appliances (stove, dryer, A/C)
• Homes converting from gas to electric with a heat pump
• Homes where the existing 200-amp service has space in the panel for new circuits

When 400 Amps May Be Warranted

• Very large homes over 4,000–5,000 square feet with all-electric systems
• Properties with multiple EV chargers (two or more Level 2 units running simultaneously)
• Workshops or home businesses with significant electrical equipment
• Homes with large hot tubs, pools, and multiple HVAC zones
• New construction where future-proofing for full electrification is desired

Load Calculation First

The decision should be based on a proper electrical load calculation, not guesswork. A Licensed Electrical Contractor can calculate your home’s demand load using the Ontario Electrical Safety Code methodology. This calculation accounts for all existing and planned loads and determines whether 200 amps or 400 amps is the correct service size. Upgrading to 400 amps when 200 amps would suffice is an unnecessary expense — these are significant infrastructure projects.

EZSMART performs load calculations and service upgrades across Ontario. Contact us to assess whether your home needs a 200-amp or 400-amp service.

Amir Azimipour

Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp