What Is a 100A to 200A Service Upgrade?
A 100A to 200A service upgrade replaces the main breaker, the load centre, the meter base and the service entrance conductors so the property can draw twice the continuous current it could before. It is not a panel swap. The whole service from the Toronto Hydro service drop or underground lateral, through the weatherhead and meter base, down to the main breaker, is rebuilt to carry 200A.
For a Toronto home that means moving from a panel with every position filled to a 42-circuit load centre on a copper bus bar, with real spare capacity left after the existing circuits transfer across. The 2/0 AWG copper service entrance conductors and the new meter base are sized to the upgraded service, and the grounding electrode conductor is verified rather than assumed.
The trigger is almost always electrification. A Level 2 EV charger draws 40A or 50A continuous, and the Ontario Electrical Safety Code treats it as a continuous load at 80%, so it eats capacity fast. Add a cold-climate heat pump, an induction range and a basement-suite subpanel, and an OESC Section 8 demand calculation on a 100A service runs out of room before the renovation is finished.
Because the meter has to come off, this is coordinated work rather than a same-hour job. We file the ESA Notification of Work, submit the service layout to Toronto Hydro, book the disconnect, complete the install, pass the inspection and hand back the Certificate of Inspection. For the rest of the residential range, see residential electrical panel upgrades.
Types of 100A to 200A Upgrade
- Overhead mast, panel in place. The service drop lands on a new mast and weatherhead, the meter base is replaced, and the new 200A load centre goes in the same position as the old one. The cleanest version of this job.
- Overhead with panel relocation. The existing panel sits in a closet or under a stair with no working-space clearance, so the new load centre moves to a compliant wall and the feeder is rerouted.
- Underground lateral. Common on rebuilt streets in Mimico, Guildwood and parts of North York. The lateral, meter base and load centre are all replaced, and any trenching or conduit work is priced separately in the quote.
- 200A service with a suite subpanel. The service upgrade and a 60A or 100A subpanel on a four-wire feeder are installed together, which is cheaper than doing them as two projects.
When Do You Need to Go From 100A to 200A?
- Level 2 EV charging. A 40A or 50A continuous load on top of laundry, HVAC and refrigeration is where most 100A services fail the calculation. Where the panel is otherwise healthy, an EV charger electrical upgrade with an EVEMS device is the alternative worth pricing.
- Heat pump conversion. Moving off gas heating adds a large dedicated load plus backup heat, and the calculation has to hold on the coldest design day, not the average one.
- Induction range plus electric water heating. Two large resistive loads that arrive together in most kitchen renovations.
- Basement suite or accessory dwelling unit. The City of Toronto expects a documented load calculation, a dedicated subpanel and a separate disconnect. See basement suite electrical upgrades.
- No spare breaker positions. Tandems in every slot and no knockouts left means the enclosure, not the breaker count, is the limit.
- Failing panel hardware. Bus-bar corrosion, double-tapped terminals or a warm enclosure means the panel needs replacing anyway, so the incremental cost of upgrading the service at the same time is small. That path is covered under electrical panel replacement.
What Drives the Cost Between $2,500 and $8,000
Four variables move a quote inside the band. Service type is the biggest: an underground lateral with trenching costs materially more than a mast and weatherhead replacement. Conductor routing is second, because the distance from the meter base to the panel position sets the length of 2/0 AWG copper and any conduit needed. Panel choice between Siemens, Square D / Schneider Electric and Eaton shifts material cost. Scope added by the calculation is the fourth: a grounding electrode conductor that has to be run to the water service, a panel relocation for working-space clearance, or a subpanel the suite plan requires.
What does not move is the ESA permit fee, which is included, and the Toronto Hydro coordination fee, which is itemised on its own line so you can see it. Where we find something after the service is opened that changes the scope, work stops and you get a revised written quote before we continue.
What to Expect on Install Day
Toronto Hydro arrives in the morning to pull the meter and drop the service. From that point the property is without power. We remove the old load centre, replace the mast or lateral and the meter base, pull the new service entrance conductors, and mount the 200A load centre. Existing circuits move across onto correctly sized breakers, arc-fault and ground-fault protection goes on the circuits that require it, terminations are torqued to specification, and the panel schedule is written and fixed inside the door.
The ESA inspector attends to review bonding, grounding, terminations and labelling. Once the Certificate of Inspection is signed, Toronto Hydro reconnects and sets the meter. On a standard overhead job, power is back the same afternoon. Before we leave, you get the certificate, the panel schedule and the itemised invoice that matches the original quote.
What Triggers a 200A Upgrade in Toronto: EV Chargers, Heat Pumps, Suites, and Inspector Flags
Most Toronto 200A upgrades are triggered by one of six real load additions or one of four inspector-flagged discoveries. The trigger determines the timeline, the utility coordination window, and whether an ESA amendment is required.
The six most common load triggers
- Level 2 EV charger install: a 40-60A dedicated circuit for a Tesla Wall Connector, ChargePoint Home Flex, or Grizzl-E Classic pushes a 100A service past its 80% continuous load ceiling.
- Cold-climate heat pump: a Mitsubishi Zuba or Daikin Aurora ducted heat pump on a 240V split-phase circuit adds 30-50A of continuous load in heating mode.
- Induction range and induction cooktop combination: a full-kitchen induction retrofit adds a 40-50A circuit plus a 20A dedicated countertop circuit.
- Hot tub, sauna, or pool heater: a 40-60A GFCI-protected circuit for a Softub, Arctic Spa, or Sundance Optima.
- Basement suite subpanel with second-suite metering: an OESC Section 26 second-suite install typically pulls a 60-100A subpanel off the main service.
- Major renovation on the ESA permit path: any addition, second-suite, or garage-loft renovation puts the panel in front of an ESA inspector.
The four inspector-flagged discoveries
- 60A fuse panel flagged during a home inspection: the buyer’s insurer refuses to bind coverage until the panel is upgraded to a 100A or 200A breaker service.
- Federal Pacific Stab-Lok or Federal Pioneer panel: insurers and ESA both push for immediate replacement due to documented breaker-trip failure rates.
- Aluminum branch-circuit wiring feeding a modernised load: insurers require an ESA-certified pigtail retrofit or full rewire before increasing service size.
- A Toronto Hydro service drop that predates 1990: older drops on 100A meter bases with corroded neutrals get replaced during the upgrade, not before.
Signs Your 100A Panel Is Overloaded: Warm Bus Bars, Nuisance Trips, Full Positions, No Spare
A 100A panel usually gives four or five obvious signals before it stops being safe. Homeowners often notice one signal at a time and only connect them at the load calculation stage.
Physical warning signs at the panel
- Warm enclosure or warm breakers: heat you can feel on the panel cover means terminations are loose, breakers are undersized for the actual continuous load, or the bus bar is starting to pit.
- Discoloured or browned breaker faces: yellowing on a Siemens QP, Square D HOM or Eaton BR breaker indicates repeated overheating on that circuit.
- A hum, buzz or occasional pop from inside the enclosure: normal AC hum is quiet. A loud or intermittent buzz signals a loose neutral or a failing breaker.
- Corrosion, rust or moisture inside the cabinet: any water ingress on a bus bar or a grounding electrode conductor lug is an immediate ESA concern.
Circuit-level and load symptoms
- Nuisance trips on the dryer, kitchen, or AC circuit: especially when the dryer and range run at the same time, or the AC compressor starts.
- Lights dimming when a large motor starts: the pump, the compressor or the microwave pulling voltage down means the service is at its ceiling.
- Every breaker position full, and tandem breakers doubled up: if the panel has no knockouts left and tandems are in every 15A and 20A slot, the enclosure is the limit rather than the amperage.
- A 100A service feeding gas heat, gas water heat, and no EV: if the calculation is already close to 100A on the current loads, the next appliance addition triggers the upgrade.
Overhead Mast vs Underground Service for a 200A Upgrade: Cost, Timeline, and Toronto Hydro Coordination
Toronto has both service styles, and which one you have decides how the 200A upgrade is priced and scheduled. The choice is set by the original build, not by preference.
Overhead mast service upgrades
- Applies to most pre-1990 Toronto Hydro service drops: a service cable from the pole to a mast on the roof, into the meter base, and down to the panel.
- Materials replaced on a 200A overhead job: a new 2 or 3 inch rigid galvanised mast, a 200A weatherhead, 2/0 AWG copper or 4/0 AWG aluminum service entrance conductors, a 200A meter base.
- Toronto Hydro coordination window: the disconnect and reconnect happen on the same day, usually within a 4-6 hour outage. The service drop reattachment is handled by Toronto Hydro on the same visit.
- Typical price band: $2,500 to $6,000 CAD depending on mast height and conductor length.
Underground lateral service upgrades
- Applies to newer subdivisions on Alectra Utilities or Elexicon Energy: a buried service lateral running from a transformer or pedestal to a below-grade meter base.
- What gets replaced on a 200A underground job: the meter base, service entrance conductors from the meter to the panel, and sometimes the lateral itself if it is undersized or aluminum-degraded.
- Trenching, conduit and civil work: if the lateral needs replacing, a trench from the transformer pedestal to the house is required, plus a locate through Ontario One Call.
- Typical price band: $5,000 to $8,000 CAD once civil work is included, with a longer timeline due to utility scheduling and locate lead time.
When the service type changes
- Overhead to underground conversion: possible but rare on a Toronto Hydro 200A residential upgrade. It requires a coordinated project with the utility and is priced as a full service change, not a panel upgrade.
