100 or 200 Amp Electrical Service?

It can be, especially in a smaller home with gas heating and no large future electrical plans. The catch is that “enough” changes quickly the moment you add an EV charger, a heat pump, a hot tub, or a basement suite, because those are the loads that push a 100 amp service toward its limits. The correct way to decide is not to look at how the home is used today but to run a load calculation that reflects your appliances and your realistic future plans, since a service that is comfortable now can become the bottleneck the first time a big new load arrives. If your home is genuinely modest, gas-heavy, and likely to stay that way, 100 amp can be perfectly acceptable, but that should be a conclusion you reach from a calculation rather than an assumption, because the cost of guessing wrong is a disruptive upgrade later.

An upgrade is most commonly triggered by adding high, steady loads such as EV charging or an electrified heating and cooling strategy, or by renovations that add a secondary unit, workshop equipment, or a batch of major new circuits. If you are already close to capacity and you want to avoid future limitations, upgrading during a renovation, while walls and access are already open, is usually far smarter than waiting until a new load forces the issue and the work has to happen around finished space. The clearest signal is a load calculation showing little remaining headroom for the additions you are contemplating. Because service work involves an ESA permit and utility coordination, timing it alongside other planned work also avoids paying twice for access and scheduling, which is a large part of why proactive upgrades tend to be cheaper and less disruptive than reactive ones.

Sometimes yes, but it depends entirely on your other loads and the result of a proper calculation. Some homes can support a lower-power charging setup or a managed-charging strategy that limits the charger’s draw when other big loads are running, while others will need a service upgrade to stay compliant and avoid overloading. A typical Level 2 charger is a substantial, steady load that runs for hours, so on a 100 amp home already carrying electric heat, a large range, or other significant loads, the headroom can disappear fast. The safe approach is to have a qualified electrician run the load calculation and confirm what the Electrical Safety Authority will accept for your final configuration, referencing the ESA guidance for EV charging equipment, rather than assuming it will fit and discovering otherwise after the charger is bought.

Not literally everything, but it gives you much more headroom for simultaneous use and, more importantly, much more flexibility to add circuits later without playing a constant game of what can we turn off. The real value of 200 amp service is not that it lets you run every appliance at full power at the same instant, which no house actually does, but that it comfortably absorbs the modern load stack of EV charging, a heat pump, cooking, laundry, and a home office coinciding during a peak evening, and it leaves room for the next addition you have not thought of yet. It also reduces the chance that a future electrification upgrade forces a second round of construction. The sizing is still governed by a load calculation, but 200 amp simply starts you with far more margin than 100.

A panel upgrade means replacing the distribution panel, the breaker panel, inside the home, which can add breaker space or modern protection but does not by itself increase how much power the home can draw from the grid. A service upgrade means increasing the capacity of the supply coming into the home, which typically involves the meter base, the service conductors, and possibly a new mast for an overhead service or new underground conductors, along with coordination with the utility for disconnect and reconnect and an ESA inspection. Most 100 amp to 200 amp jobs are service upgrades, not just panel swaps, because raising the amperage means the incoming supply and metering equipment have to be rated for the higher capacity. Understanding which one you actually need matters, because a panel swap alone will not solve a capacity problem, and quotes should be clear about the full scope.

Not always. Some heat pump systems, in well-designed and efficient homes, can operate on 100 amp service, but the risk of running short rises quickly when you add electric backup heat, other significant loads, or EV charging. The deciding factor is the total calculated demand and, crucially, how the loads coincide during peak conditions, because a cold Ontario evening can stack heating support, cooking, and charging at the same time. That is exactly the moment a marginal service gets into trouble. If you are electrifying your heating, or combining a heat pump with an EV or a suite, 200 amp is often the safer future-proof choice, and even where a calculation shows 100 amp is technically adequate, it is worth asking how much headroom is left for anything you might add afterward before committing to the smaller service.

The service size itself does not make you use more electricity – your appliances and your habits do. A larger service is like a wider driveway: it allows more vehicles, but it does not force you to buy them, and simply having 200 amp capacity available does not draw any extra power. What often confuses people is that many homeowners upgrade precisely because they are adding loads such as an EV charger, a heat pump, or a basement suite, and those loads do increase consumption depending on how much they are used. So the upgrade and a higher bill can appear together, but the cause is the new equipment, not the amperage of the panel. If you upgrade the service and add nothing, your consumption and your bill stay essentially the same as before.

Yes. Service changes and most significant electrical work require proper permitting and inspection through the Electrical Safety Authority, handled by a licensed electrical contractor. In practice your electrician pulls the ESA permit, arranges the inspection, and coordinates the utility disconnect and reconnect, so the paperwork is usually managed for you, but it is not optional and it does take time. That is why it should be planned early in a renovation or new build rather than treated as a last-minute detail, because waiting on an inspection or a utility appointment can become a schedule bottleneck that holds up drywall, finishes, or occupancy. Confirming who is pulling the permit and how the inspection and reconnection are sequenced is one of the questions worth asking any electrician before the work starts, alongside the scope of the upgrade itself.

Common signs include breakers that trip frequently when several loads run at once, a panel with no physical space left for additional breakers, and electricians telling you they cannot add the circuit you want without a service upgrade. Renovations that keep pushing you into subpanels and workarounds are another clue, as is a pattern of having to think about what to turn off before running a big appliance. Those symptoms are useful, but the most reliable indicator is not a symptom at all – it is a load calculation showing that little capacity remains for the additions you are considering. Because the visible signs often appear only once you are already at the edge, having the calculation done before you commit to a new EV charger, heat pump, or suite is the way to know where you stand rather than discovering the limit the hard way.

In many cases, yes, especially if you want EV charging, a heat pump, a suite, or any meaningful future flexibility, because new construction is by far the easiest and cheapest time to make the decision. Running the larger service during the build, while everything is open and the utility connection is being made anyway, costs far less than coming back to upgrade a finished home later, and it removes the single most common source of service regret. There are still cases where 100 amp is reasonable for a new build – a clearly modest, gas-heavy home with no electrification plans – but you should be honest with yourself about future upgrades, since plans change and electrification is the clear direction of travel. When the incremental cost at construction is modest and the cost of upgrading later is high and disruptive, the default for a new home leans strongly toward 200 amp unless a load calculation and your firm plans genuinely point the other way.