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Load calculation: is your panel still enough?
What the Code says, what it changes in your home, and when to act. Checked against official sources.
In short
A full panel isn’t necessarily an outdated panel, and a half-empty panel can be at its limit. What decides isn’t the number of breakers: it’s the load calculation. The tool below gives you an idea in one minute. The real calculation comes with the quote, and it’s free.
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What is a load calculation for?
A load calculation adds up what your home can demand at the same time, at the worst moment: a January evening, heating at full blast, the dryer running, supper on the stove, the car charging in the driveway.
That total is what gets compared with the capacity of your service. Not the number of circuits, not the age of the panel, not the feeling that “it trips often”. A 100 amp panel feeding a gas-heated house with an electric water heater has a lot of margin. The same panel in an all-electric house with an EV charger has none.
It’s also what sets the service’s capacity when it’s increased, and it’s a master electrician who signs it.
Is your panel enough?
Six questions. The result is an estimate, not an official calculation, but it will tell you which way you’re heading.
Is your 100 amp panel enough?
Check what you have and what you want to add. We estimate your home’s load using the method in the Québec Construction Code. The starting values are examples: replace them with yours.
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The basement counts at 75%, and only the part over 1.8 m high.
Add up the watts written on each baseboard (1,000 W = 1 kW).
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Check only if a system stops them from running together. If you’re not sure, leave it empty.
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Value written on the spa’s nameplate.
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Under the 2026 Code, an EV charger counts at 100%. A load controller like the DCC-9, which we install, cuts the charger when the house draws a lot: the manufacturer states it lets you connect the charger without changing the load calculation. Our master electrician confirms whether your installation qualifies.
See the calculation details
Estimate based on the method in section 8-200 of the Québec Construction Code (chapter V, 2026). For an existing house, your actual peak demand over the last 12 months can also be used, and it is often lower. Our master electrician confirms the calculation on site.
What weighs most in a house
Not all appliances are equal. Here is the real order, from the hungriest to the most discreet.
| What you have | Weight on the service | Why |
|---|---|---|
| Electric heating | Very heavy | It’s by far the biggest item in Québec, and it runs when everything else is running too. |
| EV charger | Very heavy | A Level 2 charger draws a sustained load for hours, often in the evening. |
| Heat pump | Heavy | It lightens the heating part of the year, but it adds to the peak. |
| Spa or heated pool | Heavy | The spa’s heater draws continuously, regardless of the season. |
| Stove, dryer, water heater | Medium | Big appliances, but they rarely all run at the same time. |
| Lighting, outlets, appliances | Light | The total counts, but it varies little from one house to another. |
When the calculation says no
When the total exceeds what the service can carry, there are two possible answers, and only one is right depending on the case.
- Not enough room in the panel, but enough amps → a sub panel is often enough, and it costs much less.
- Not enough amps → the service has to go up. Adding a box doesn’t create amps.
Replacing a 200 A panel takes one day, including about five hours without power; the price is in the written quote, free of charge. We handle the steps with Hydro-Québec.
Who is allowed to replace a panel in Québec?
The question comes up all the time, and the answer surprises people: it isn’t a question of skill, it’s a question of law.
“No one may carry out electrical work of any kind, in their own residence or elsewhere for others, unless they are an electrical contractor.” “A person who contravenes the Master Electricians Act and the Building Act is liable to a fine of $5,000 to $200,888.” (our translation)
Corporation des maîtres électriciens du Québec
The official load calculation is part of the job. STM Électrique inc. is a member of the CMEQ and holds RBQ licence 5815-0137-01.
Frequently asked questions
Does the tool replace a real load calculation?
No. It gives you a direction in one minute. The official calculation takes into account the actual floor area, the exact power of each appliance and the demand factors set out in the Code. It’s done by a master electrician, and it’s free with the quote.
My main breaker trips: does that mean I’m short on amps?
Often yes, but not always. A fault on one circuit can trip the main breaker. The load calculation tells you whether it’s a question of capacity or a problem to look for elsewhere.
How many amps does an EV charger need?
It depends on what’s left, not on the charger. A gas-heated house on 100 amps can often take one. An all-electric house, rarely. That’s exactly what the calculation determines.
Does Hydro-Québec require the calculation?
No, Hydro-Québec doesn’t ask us for it when a service is increased. The calculation is used to size the service and the panel, and only a master electrician can file the service request.
Unsure about your panel?
Send us a photo and we’ll reply with the next steps.
CMEQ member · RBQ licence 5815-0137-01
Have your calculation confirmed
Sources
The requirements cited in this guide come from the official sources below; page checked on September 18, 2026.
Read next
- Electrical panel upgrade in Québec: cost and how the day goes
- Is there a grant?
- Is 100 amp service enough for your house?
- 200 amp panel: is yours enough?
- Sub panel: when and how to add one
- Panel standards
- Outdoor electrical panel: what Québec’s code allows
- Distribution panel
- Master electrician in Québec: role and how to check
- Renovating: what the Code requires for electrical