What key factor must be considered when using a plumb bob to check the alignment of a pole?

When using a plumb bob to check the alignment of a pole, the position of the plumb bob string is a crucial factor. The purpose of a plumb bob is to provide a vertical reference line that allows you to determine whether the pole is indeed vertically aligned. For accurate alignment, the string and bob must be properly positioned and free from any obstructions that might affect their verticality. If the plumb bob string is not vertical, the alignment measurements will be inaccurate, which could lead to improper installation of the pole.

While considerations such as the length of the pole, environmental factors like wind, and the type of soil may impact the overall installation and stability of the pole, they do not directly affect the immediate use of a plumb bob for checking vertical alignment. Thus, focusing on the position and tension of the plumb bob string is essential for achieving precise alignment.