What exception allows reduction in the easement distance required for overhead installations?

The correct option reflects a crucial aspect of easement regulations regarding overhead installations. Prior permission is essential because it signifies that any reduction in the required easement distance has been approved by the relevant authority or property owner, ensuring that all parties involved are informed and consent to the change. This permission is necessary to maintain legal compliance and avoid conflicts that can arise from encroachments or unapproved modifications.

In the context of utility installations, having prior permission ensures that safety requirements, property rights, and public interests are respected. It fosters cooperative relationships between service providers and property owners, leading to smoother project execution.

Other options may not hold the same legal weight or universality required for modifying easement distances. For instance, while written consent from neighbors can be important in some scenarios, it does not necessarily provide the formal backing needed for such adjustments. Similarly, long-term agreements or local government approval may not inherently encompass the specific consent needed for easement reductions unless they are explicitly detailed in those documents.