Before starting the entrance installation, you should check the distance from the rail centerline to the _______ line at each floor?

In the context of elevator entrance installation, it is essential to check the distance from the rail centerline to the sill line at each floor before beginning the installation. The sill line refers to the horizontal surface at the bottom of the doorway where the door sill is installed. This measurement is crucial for ensuring that the door operates correctly and aligns properly with the entrance. If the distance to the sill line is not accurate, it could lead to improper door installation, resulting in issues such as gaps or misalignment, which can affect the functionality and safety of the elevator system. This check helps to establish a consistent and proper installation height for the elevator door, promoting safe and efficient operation. Proper alignment not only ensures ease of use but also complies with safety regulations and standards pertinent to elevator installations.