Speed Sign Placement Requirement/regulation

I have seen the section about the size color etc of a speed limit sign, but I can not find where it stipulates the placement of it.

When you enter a road (making a right or left turn) usually within the first 50 meters there is a sign telling the drivers what the speed limit is.

So, I'm guessing there must be a regulation that states where signs need to be posted, am I wrong?

I'm not aware of any requirement that they be posted at every intersection, etc. The only requirement I'm aware of is the distance between signs (under the same o-reg as sign size, etc).

There is no requirement for a sign to be a certain distance from the intersection, as it would be near to impossible to enforce, as the road is prolonged through the intersection.

But they do get specific about how big the signs have to be and the distance from the street.