100A vs 200A panel: how to tell if you need an upgrade before adding a heat pump or EV

Not everyone who asks us for a 200A upgrade needs one. Some homes pass the load calculation as they are, or pass with a load-management device and skip the upgrade.

You can check most of this yourself with a flashlight. Open the panel door only. Don't remove the inner cover.

Check your panel

1. Read the main breaker. The big breaker at the top has a number on the handle: 60, 100, 125 or 200. That's your service size. At 200 you can probably stop here. At 100 or less, keep going.

2. Count the breaker spaces. A 100A-era panel often has 24 spaces or fewer. If they're full or doubled up with tandem breakers, you're out of room even if you have capacity. That's cheaper to fix than a service upgrade.

3. Look for "Federal Pioneer," "Stab-Lok" or "Zinsco." Check the door label and the breakers. Any of those names means the panel should be replaced, whatever you're adding. These breakers have a documented history of failing to trip, and many insurers now push owners to replace them. See our guide to Federal Pioneer panels.

4. List your big loads. Anything on 240V or drawing serious current. Typical breaker sizes:

Don't just add these up against 100. The code calculation discounts loads that rarely run together. As a rule, a 100A house with an electric range, dryer and water heater can take one more big load. A heat pump or an EV charger is usually fine. Both, plus a hot tub, and the calculation fails.

When 100A is enough

BCEC 2024 recognizes electric vehicle energy management systems (EVEMS). They monitor your service and slow or pause EV charging when the rest of the house is using a lot of power.

A 100A house that fails the calculation with a 48A charger can often pass with the same charger behind an EVEMS, because the managed charger no longer has to be counted at its full load. The car charges at full speed at 2 a.m. and backs off while the stove and dryer run.

An EVEMS makes sense when:

• You're adding only an EV charger and the calculation fails by a small margin. An EVEMS or a charger with built-in load management usually costs far less than a service upgrade.
• The panel is otherwise healthy, with modern breakers and spare spaces. Load management won't fix a bad panel.
• You can live with slower charging when the house is using a lot of power. Most people never notice. If you drive 300 km a day, you might.

When to go to 200A

We recommend the upgrade when any of these apply:

• Full electrification. Heat pump, EV and induction range, now or within five years. Load management can hold back one flexible load. It can't hold back a heating system. If you're moving off gas, upgrade once.
• No spaces and no capacity. If you'd need a sub-panel and an EVEMS and would still only just pass the calculation, the 200A upgrade usually costs less.
• The panel is a liability anyway. FPE, Zinsco, rust, two wires under one breaker screw, or a 60A service (still around in James Bay and Fernwood). You're replacing it regardless, so size it right.
• A suite or major renovation is coming. A legal secondary suite often pushes a 100A service over its limit on its own.

A 100A→200A upgrade is quoted after a site visit, and there's also a BC Hydro connection charge. What affects the cost is in our panel upgrade cost guide and on the panel upgrade service page.

Don't let anyone sell you a 200A upgrade, or talk you out of one, without a load calculation on paper.

---

Keep reading