In my part of the world here is how it works:
In new work the ONLY place neutural and ground come together is in the meter socket. The cable from the meter socket to the main service panel is 4 conductors with the neutural conductor being insulated. The neutural is not allowed to be derated, and must be the same as the hot conductors. In the panel the branch circuit neuturals and grounds are landed os seperate terminal strips, the can is bonded to the GROUND, but NOT the neutural, same as a sub panel. Theory being that in a three wire service (ground and neutural on same conductor) the neutural/ground conductor would not be big enough to carry the neutural load and any ground fault current that might occur, at least that is the way it was told to me.
