Panel and service upgrades·Toronto and the GTA

What size electrical service does a duplex, triplex or fourplex need?
Toronto multiplex answer, with real numbers (2026)

Short answer

Often less than you think. Each unit is calculated on its own, then the Ontario Electrical Safety Code combines them: 100% of the largest unit, 65% of the next two and 40% of the fourth, because households rarely peak together. A real Toronto duplex with an electrically heated suite came to 176 A and fits on one 200 A service. A fourplex with electric heat often lands above 200 A, and the calculation shows by how much.

By Energable, engineering-led electrical, Toronto. Updated November 2026.

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How a multiplex service is sized

Since 2023 Toronto allows up to four units on most residential lots, and up to six in some wards. The electrical service is sized the same way for each of them.

Calculate each unit on its own. Floor area, heating and cooling, range, dryer, water heater and any EV charger, each by the Code's single-dwelling rules. In the duplex below, the upper unit came to about 109 A and the basement suite to 104 A.
Combine the units by the Code's multi-unit method. 100% of the largest unit, 65% of the next two, 40% of the next two, then 25% of the rest. Adding the units straight together oversizes the service.
Plan the metering and panels. Each unit usually gets its own revenue meter on a multi-meter centre, and its own panel, so every household pays its own bill. Shared equipment like a common furnace or laundry is fed from one panel or a small house panel.
Decide early on electric heat and EV chargers. These are what push a multiplex past 200 A. Counting them before the service is ordered tells you whether 200 A holds, whether a load manager covers the chargers, or whether the building needs a larger service.

Real Toronto homes

Two Toronto homes, more than one household

A new duplex calculated by the multi-unit method, and a former duplex brought back onto one service.

Oakwood Village: new duplex

Owner's unit plus an electrically heated basement suite

Upper unit, calculatedOwner's home

109 A

Basement suite, calculated4-zone radiant floor and a mini-split

104 A

Both added straight togetherWould suggest a larger service

213 A

Combined by the Code's method100% of the larger plus 65% of the smaller

176 A

The service200 A, two meters, two panels

200 A

One 200 A service for two homes, with about 24 A to spare and a meter and panel for each unit.

The Beaches: former duplex

Two meters and two 125 A panels consolidated

Combined highest demandBoth old meters, 12 months

19.5 A

x 1.25, by the CodeESA Bulletin 8-3-15

24.4 A

Plus a 48 A EV chargerAt its full rating

72.4 A

The new serviceOne 200 A service

200 A

Two old services became one modern 200 A service, with a full-speed charger and plenty of room for electric heat.

Duplex, triplex or fourplex: what changes

A duplex with gas heat rarely needs more than 200 A. Each added unit adds its own range, dryer and water heater, but the Code's multi-unit factors mean the third and fourth units count at 65% and 40%.

As a simple illustration, four units that each calculate to 100 A combine to 270 A, not 400 A. That is more than one 200 A service, so a fourplex like that would need a larger service or a load plan that brings it under.

Electric heat and EV chargers decide the size

Heat pumps, electric baseboard, radiant floors and EV chargers are counted at full value inside each unit, and they are what push a multiplex over 200 A. A certified load manager can keep chargers within the service by pausing them during the few peak hours.

Deciding on these before the service is ordered avoids paying for capacity the building never uses, or opening walls later to add it.

Meters, panels and Toronto Hydro

Toronto Hydro sets the metering and the service connection, and the timing can run several weeks, so it belongs early in the schedule. A multi-meter centre gives each unit its own meter, and each unit gets its own panel. We handle the load calculation, the Toronto Hydro application and the ESA permits, then wire the building on the framing schedule.

Case studies

See it on real jobs

Duplex

A new duplex on one 200 A service

Oakwood Village. 176 A calculated, two meters, two panels.

Read the case study →Service upgrade

Two old panels into one 200 A service

The Beaches. A former duplex, with a 48 A charger.

Read the case study →Laneway house

EV charger at a laneway house, no upgrade

Midtown. A 200 A service split into two 100 A meters.

Read the case study →

Load assessment first

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Building a duplex, triplex or fourplex? Send the drawings and the equipment list for each unit. We run the load calculation, size the service and meters, and send a fixed quote within 1 to 2 business days.

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Straight Answers

Common Questions

The kind we would give before you commit a dollar of capital. Tap a question.

Do I need a 400 amp service for a duplex in Toronto?

Usually not. The Code calculates each unit, then combines them at 100% of the larger and 65% of the smaller. A Toronto duplex with an electrically heated basement suite came to 176 A and runs on one 200 A service.

What size service does a fourplex need?

It depends on how each unit is heated and what it adds. The units are combined at 100%, 65%, 65% and 40%. A fourplex on gas heat may fit on 200 A; with electric heat or EV chargers in every unit it usually needs more, and the load calculation shows exactly how much.

Does each unit in a multiplex need its own meter?

It is the usual way to build it in Toronto. A multi-meter centre on the Toronto Hydro service gives each unit its own meter, and each unit gets its own panel, so every household pays its own bill.

Can I add EV chargers to a triplex or fourplex?

Yes. Chargers count at full value in the calculation, so with several units a certified load manager is often the way to fit them on the service without an upgrade. Roughing in conduit while the walls are open keeps that option cheap.

Who handles Toronto Hydro and ESA for a multiplex?

We do. The load calculation, the Toronto Hydro service application, the ESA permits and inspections, and the Certificates of Acceptance for each unit are part of the work.

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