Plant North

Imagine a plant built so that one side was angled 20º from north. Then plant north (conforming to the lines of the building) is 20º from true north.

Buildings are general built to suit the plot, utilities, local layout, etc.

Saying one side is the 'North' is for practical purposes.

It is not true North, but off by less than 45° (much) in either direction.

I'm assuming you mean magnetic north and true north...

Magnetic north is where the compass points, and true north refers to the planet axis of rotation...

..."Today, the Magnetic North Pole moves about 25 miles each year. Soon, it will be at 86.471° N and 178.755° W, a distance less than 212 nautical miles away from the Geographic North Pole"...

https://setcompass.com/TypesofNorth.htm

Plant north is strictly for simplification in drawing up plans....

..."Defining a starting point of the site related to the North / South direction, is one of the first steps in setting up a coordination system.

In principle, with a simple reliable compass the direction of the magnetic north can to be determined. In the image below the true north is at 18°. As a draftsman would work with the true north coordinates, he will immediately find out that each line from west to east and from north to south at an angle of 18° must be drawn.
To avoid this, a Plant North will be determined. In the example below, the true north, 18° is reversed, draftsmen and construction contractors will be grateful for it.

General there will be tried, to approach the true north-south coordinates as close as possible.
A rule is, that the angle between true north and Plant North can not exceed 45°. At 50°, for example, the Plant North would be on the right side, so on the Eastern side of the image."...

1 = Official reference point
2 = South West angle of new plant
X = East West distance from new plant to reference point
Y = North South distance from new plant to reference point

http://www.wermac.org/documents/coordination_part1.html

Duplicate thread.

The forum cannot do this. The information will be found on a plot plan drawing for the plant in question, which cannot be seen from here.