Is it alright to install the main electrical panel in an attached garage?

Canada is a big place. Check your local or provincial building codes.

If your electrician is local and says it is okay, then it is probably okay.

You could have the maiin service disconnect there, and a sub-panel elsewhere though, but a panel in a garage (on a board) can be sealed, or more accurately, where the branch lines leave the garage can be sealed.

I have often placed the main Panel in the garage, there are no problems with it, and it allows for mounting it on the surface. This is much more desired since your electrician can make future changes much easier and cheaper when the panel is accessible and not recessed in a wall. Keeping you panel closest to the kitchen is the best idea since this is where most of the circuits in a home will be and will save money on cable. With your panel on the surface sealing will be easy for your builder. Take your Electricians advice.

There are different conventions for different parts of the country. some are inside the house somewhere, some are in the garage and some are even on an exterior wall facing outside.

Inside the garage is a fine place for the panel. You just have to have it in a place where you can easily access it and nothing will be in front of the panel for 4' (I think that's the code) might be a bit more.

It'll be the easiest way to do it. Unless some of the runs of wire will be very long, I would go with his plan. Also with it mounted in the garage, you could power the house by generator a whole lot easier. There's no real reason I can think of not to put it in the garage.

Here in North carolina, it is not the desired place, but at the same time, it's not illegal, either.

All the code states is that it be installed where it is protected against physical damage and not be in any closet or bathroom. Good luck and may God bless.

This is very common in Colorado, especially with newer home construction.

Its pretty much normal in the US....Not unusual at all