Sag s:
Thedistance between the highest point of electric poles or towers and the lowest point of a conductor connected between two poles or towers.
Span length:
It is the shortest distance between two towers or poles.
Sag\(s = \frac{{W{l^2}}}{{8T}}\)
Where,
S is the sag of the conductor
W is the weight of the conductor
l is the span length of the conductor
T is the working tension on the conductor