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Distribution panel: what it does and when to replace it
Main panel, distribution panel, sub panel: what each word means, and when a sub panel is enough.
In short
The distribution panel is the technical name for what most people simply call “the electrical panel”: the box that receives Hydro-Québec’s supply and divides it into the house’s circuits. Replacing it takes one day for a 200 A panel; the price is in the quote.
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Distribution panel, main panel, sub panel
Three words for three things, and people mix them up all the time.
| The word | What it is | Where it is |
|---|---|---|
| Main panel | The one that receives Hydro-Québec’s supply and carries the main breaker | Only one per dwelling, usually in the basement or a utility closet |
| Distribution panel | The generic term: any box that divides electricity into circuits. The main panel is one. | Wherever there are breakers |
| Sub panel | A secondary panel supplied by the main one, to serve one area | Garage, workshop, finished basement, added unit |
The distinction matters for a practical reason: a sub panel costs considerably less than replacing the main panel, and it solves a good number of situations.
When a sub panel solves the problem
If your main panel still has capacity but no more physical space — no more free slots to add breakers — a sub panel is often the right answer. It’s installed near the area to be served, and the new circuits are connected to it.
It’s common when finishing a basement, adding a workshop, or when a detached garage needs more than one outlet.
When it fixes nothing
If the problem isn’t space but capacity, a sub panel changes nothing. Adding a box doesn’t create amps: it redistributes the ones that already exist.
It’s the typical case of a house on 100 amps that wants to add an EV charger and a heat pump. There, the service has to be upgraded, not subdivided. A load calculation settles the question in a few minutes.
The simple rule: not enough room → a sub panel may be enough. Not enough amps → the main panel has to be replaced, and often the service entrance with it.
What does it cost?
The price of replacing a 200 A main distribution panel is in the written quote, free of charge. It depends on the target amperage, the condition of the service entrance and the mast, and the number of circuits to redo.
A sub panel costs considerably less, because it requires neither a Hydro-Québec disconnection nor redoing the service entrance. It’s often the most economical solution when it applies.
Who is allowed to replace a panel in Québec?
Replacing a main panel or adding a sub panel is electrical work, and in Québec the law reserves it to electrical contractors, even in your own home; the CMEQ points out that the fine goes from $5,000 to $200,888. STM-Électrique is a CMEQ member, with RBQ licence 5815-0137-01.
Frequently asked questions
What’s the difference between a distribution panel and an electrical box?
None in everyday language: both mean the breaker box. “Distribution panel” is simply the term used in specifications and standards.
Does a sub panel require a Hydro-Québec disconnection?
No, in most cases. That’s exactly what makes it faster and cheaper than replacing the main panel.
How do I know whether it’s space or capacity that’s missing?
With the load calculation. Looking at the panel isn’t enough: a full panel can have capacity, and a half-empty panel can be at its limit.
Can I do it myself?
No: even at home, it’s work reserved to an electrical contractor under the Master Electricians Act.
Not sure whether you need a sub panel or a new panel?
Send us a photo of your open panel: we’ll tell you which way to go.
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