How far should the top of an extension ladder extend beyond the support point when working on a rooftop unit?

When using an extension ladder to access a rooftop unit, safety regulations recommend that the top of the ladder extends at least 3 feet beyond the support point, such as the roof edge. This additional height provides a secure handhold for the worker as they transition from the ladder to the roof, thereby reducing the risk of falling or slipping during the ascent or descent.

This precaution is especially important in scenarios involving elevated surfaces where loss of balance can lead to serious injury. Extending the ladder only 2 feet or any less would not provide adequate support and could potentially compromise safety when navigating the area. Conversely, extending beyond 3 feet offers the necessary leverage while ensuring stability and security. Therefore, the requirement for an extension of 3 feet aligns with established safety practices for ladder use in professional settings, making it the correct answer.