When is it essential to use the intermediate pull technique during fiber-optic cable installation?

The intermediate pull technique is particularly essential when there are multiple 90° bends on the cable route. This technique allows for the gradual tension transfer and helps manage the stress on the fiber-optic cable as it navigates sharp turns. When fiber-optic cables make abrupt turns, they can be susceptible to damage due to excessive bending or tension. By using the intermediate pull technique, installers can ensure that the curvature of the cable does not exceed the allowable bending radius, thus maintaining the integrity of the fiber and reducing the risk of damage during installation.

In scenarios involving flat terrain or adverse weather conditions like rain, other techniques or considerations may be more relevant, but these do not specifically relate to the challenges presented by sharp bends in the installation path. Additionally, while HASB methods may involve specific installation strategies, the connection between those methods and the necessity for the intermediate pull technique is not as direct as in the case of navigating bends. Therefore, the focus on managing multiple bends effectively through the intermediate pull technique makes it the correct answer.