100A vs 200A: does your home actually need a service upgrade?
"You should really upgrade to 200 amps" might be the most common line in residential electrical — and sometimes it's true, sometimes it's a $3,000+ project you didn't need. Here's how to tell the difference.
What service size actually means
Your electrical service is the total amount of power your home can draw from the grid at once. Think of it as the width of the pipe feeding your house. Most older Ontario homes have 100-amp service; newer builds typically have 200. A 100-amp pipe isn't "old" or "bad" — it's simply sized for a certain amount of simultaneous demand.
When 100A is genuinely fine
If your home heats with gas, cooks with gas, and you don't own an electric vehicle, 100 amps handles a typical household comfortably — even with air conditioning. Plenty of homes run on 100A for decades without a single issue. If someone tells you to upgrade "just because it's old," ask them to show you the math.
When you actually need 200A
The honest triggers are the big electric loads: an EV charger, an electric or heat pump heating system, a hot tub, a secondary suite, or an electric range and dryer stacked on top of several of the above. Each of these is a heavy, sustained draw, and once you combine two or three, a 100-amp service runs out of headroom on paper — which means it fails the load calculation, and ESA won't approve new additions to it.
The middle path most homeowners don't hear about
Here's what a good contractor tells you and a lazy one doesn't: a standard load calculation assumes your major loads could all run at the same time — stove, dryer, AC, water heater, everything at once. In real life, that almost never happens. Your service spends most of its life nowhere near its limit.
That's where smart load analysis comes in. Instead of the worst-case paper math, your home's actual electrical demand can be measured, and in many cases the real numbers show there's plenty of room for an EV charger on the service you already have. The electrical code allows this — it's just more work than quoting an upgrade, so many contractors skip it.
And for homes that are genuinely close to the limit, a load management device can bridge the gap: it monitors your home's total draw in real time and pauses EV charging during peaks. Either path costs a fraction of a full service upgrade. Neither is right for every home, but both should be on the table before anyone quotes you thousands for new service.
Still on a fuse panel? Different conversation
If your panel has round screw-in fuses instead of switches, capacity math is the least of it — insurance, fire safety, and modern code protection all come into play, and it's the one case where we'll genuinely tell you to upgrade. We wrote a full guide on it: fuse panel vs breaker panel — why older homes should upgrade.
The answer is arithmetic, not opinion
Whether you need 200A isn't a judgment call — it's a load calculation defined by the electrical code. Any contractor recommending an upgrade should be able to show you the numbers: your existing demand, the new load, and where it exceeds capacity. If the recommendation comes without the math, get a second opinion before you spend thousands.
A service upgrade also involves your utility company and coordination that many contractors underestimate, which is where projects stall. It's the part of the process we know best.
Ask us whether your home actually needs the upgrade — free assessment →