Markham is one of the fastest-changing communities in the Greater Toronto Area. You have 1960s and 1970s bungalows in Milliken and Thornlea sitting a few streets away from new builds in Cornell and Wismer, and the electrical systems behind those walls are decades apart. That mix is why the two calls we take most often from Markham homeowners are the same two: my panel can’t handle any more circuits, and my wiring is old and I don’t know if it’s safe.
This guide explains how panel upgrades and rewiring actually work in Markham — the warning signs, the permit and inspection rules under the Ontario Electrical Safety Code, how the work unfolds day by day, and what a licensed electrician should be telling you before anything is quoted. Our team has more than 20 years of experience and 30+ licensed electricians serving Markham and the surrounding GTA.
When Does a Markham Home Need an Electrical Panel Upgrade?
Most older Markham homes were built around a 60-amp or 100-amp service. That was adequate when a household ran a stove, a furnace fan, a fridge and a television. It is rarely adequate now — a heat pump, an induction range, a hot tub, a finished basement and an EV charger can each want a dedicated circuit, and there is only so much room in a panel.
Signs your panel is at its limit
- No spare breaker spaces. If every slot is filled, or someone has installed tandem breakers to squeeze in more circuits, you are out of capacity.
- Repeated breaker trips on the same circuit, especially when the microwave and kettle run together.
- Lights dim when the air conditioner or a large motor starts up.
- A fuse panel instead of breakers. Fuse services are still out there in older Markham homes and often complicate home insurance.
- Warmth, buzzing, scorch marks or a burning smell at the panel. Stop and call an electrician — this is not a wait-and-see item.
- You are planning an EV charger, a hot tub, air conditioning or a basement suite. A load calculation should come before you buy the equipment, not after.
What a 100A to 200A upgrade involves
A service upgrade is more than swapping a box. A licensed electrician performs a load calculation for your home, coordinates the service disconnect and reconnect with the local utility, and replaces the panel, main breaker, service mast or conduit, meter base, and the grounding and bonding as required. Existing branch circuits are transferred and relabelled, and modern protection such as AFCI and GFCI breakers is added where the Code calls for it.
Most residential panel upgrades are completed in a single day, with power off for a portion of it. Scheduling of the utility disconnect and the ESA inspection can add calendar days on either side, so it is worth booking ahead of a renovation rather than in the middle of one. You can read more on our electrical panel upgrades page, and our guide to 200 amp panel upgrades walks through how to tell whether 200A is the right target for your home.
Rewiring an Older Markham Home
Rewiring means replacing the branch circuit wiring running through your walls, ceilings and floors. It comes up most often in homes built before the mid-1970s, and in homes where past owners added circuits themselves.
Warning signs worth acting on
- Two-prong outlets throughout the house, which usually means there is no ground.
- Cloth-covered or brittle insulation visible in the basement or attic.
- Knob-and-tube or aluminum branch wiring, both common in specific eras of Ontario housing and both a frequent insurance question.
- Discoloured or warm outlets and switch plates.
- Extension cords in permanent use because there simply aren’t enough outlets.
- Undocumented DIY work — junction boxes buried in drywall, or splices with no box at all.
Full rewire or partial?
A full rewire replaces everything from the panel out. A partial rewire targets the circuits that are actually failing — often the kitchen, bathrooms, and any run still on original wiring — while sound modern circuits are left in place. Which one makes sense depends on the age and condition of the wiring, whether walls are already open for a renovation, and what your goals are. An honest assessment starts with an electrician opening a few boxes and looking, not with a number over the phone.
Rewiring is far less disruptive when it is scheduled alongside other work. If you are already replacing flooring, gutting a bathroom or finishing a basement, that is the moment to do it. Our wiring and rewiring services page covers scope in more detail, and if the project is part of a larger renovation, see electrical service upgrades and remodeling.
Permits and ESA Inspection in Markham
In Ontario, electrical work is governed by the Ontario Electrical Safety Code and administered by the Electrical Safety Authority (ESA). A notification of work — commonly called an electrical permit — is required for a service or panel upgrade and for rewiring. This is separate from any building permit the City of Markham may require for the wider renovation.
A licensed electrical contractor takes out the ESA notification, does the work to Code, and arranges the inspection. When it passes you receive a Certificate of Acceptance. Keep that document: it is what a home inspector, an insurer or a buyer’s lawyer will ask for later. Unpermitted electrical work is one of the more common ways a real estate closing gets complicated, and it is entirely avoidable. Our Ontario electrical permit guide explains the process step by step, and this article on the Ontario Electrical Safety Code covers why the rules exist.
What to Expect from Our Markham Service Call
- Assessment. We inspect the panel, service entrance, grounding and a representative sample of outlets and junction boxes, and run a load calculation for the equipment you plan to add.
- Written scope and quote. You get the work itemized in writing, including the ESA notification and inspection, before anything begins. Cost depends on panel size, service capacity, the condition of the existing wiring and how accessible the runs are — contact us for a quote rather than relying on a generic figure.
- Scheduling. We coordinate the utility disconnect where a service upgrade is involved and give you a realistic window for the power outage.
- The work. Licensed electricians on site, drop sheets down, circuits labelled properly at the end.
- Inspection and sign-off. ESA inspects, and you receive your Certificate of Acceptance.
Practical Tips for Markham Homeowners
- Photograph your panel with the door open before you call. It speeds up the conversation considerably.
- Plan the panel around your five-year list, not just today’s problem. An EV, a heat pump or a basement suite all draw from the same service.
- Test your GFCI outlets monthly using the test and reset buttons — bathrooms, kitchen counters, garage and exterior.
- Ask for the ESA Certificate of Acceptance in writing at the end of every job, and file it with your home records.
- Verify the contractor’s ECRA/ESA licence number before work starts. Any legitimate contractor will give it to you without hesitation.
- Don’t add a subpanel to dodge an upgrade. A subpanel divides existing capacity; it does not create more of it.
Frequently Asked Questions
How much does an electrical panel upgrade cost in Markham?
There is no single figure. The cost depends on your target service size, whether the mast, meter base and grounding need replacing, how much of the existing wiring can be reused, and the ESA notification and inspection. We assess the home first and give you a written quote — call +1 (647) 832-3800 for a free estimate.
Do I need a permit to rewire or upgrade a panel in Ontario?
Yes. Both require an ESA notification of work and an inspection. A licensed electrical contractor files it on your behalf and hands you the Certificate of Acceptance once the work passes. A separate City of Markham building permit may also apply depending on the scope of the renovation.
Can I stay in my home during a rewire?
Usually, yes. Rewiring is normally staged room by room or floor by floor so that most of the house keeps power overnight. A panel or service upgrade does mean a full outage for part of one day, which we schedule with you in advance.
How long does a panel upgrade take?
The physical work on a typical Markham home is generally a single day. The overall timeline is usually longer because it includes the ESA notification, coordinating the utility disconnect and reconnect, and the inspection appointment.
Do you install EV chargers at the same time as a panel upgrade?
Yes, and combining them is normally the more sensible sequence — the load calculation is done once and the charger circuit is run while the panel is already open. See our EV charger installation service for details.
Book a Licensed Electrician in Markham
Whether you need a straightforward 100A to 200A service upgrade, a partial rewire ahead of a renovation, or an honest second opinion on wiring you’ve inherited, our licensed electricians work to the Ontario Electrical Safety Code and handle the ESA notification and inspection for you. We serve Markham, North York, Toronto and the wider GTA, with 24/7 emergency electrical service when something can’t wait.
Call +1 (647) 832-3800 for a free estimate, or request a quote online.