Length of Cable with Sag

        

Length of a Cable with Sag Formula
\( CL \;\approx\; L + ( 8 \; h^2 \;/\; 3 \; L ) \)
Symbol	English	Metric
\( CL \) = Cable Length	\(ft\)	\(m\)
\( L \) = Length of Span	\(ft\)	\(m\)
\( h \) = Height of Sag	\(ft\)	\(m\)

The length of a cable with sag is the effective length of a suspended cable (such as a fiber-optic or copper wire) when it is strung between two supports, and due to its weight, it sags rather than forming a straight line.

Factors to Consider

Actual Length vs Horizontal Distance  -  The actual length of the cable is longer than the horizontal distance between the two supports because of the sag.
Sag  -  The sag is the vertical distance between the lowest point of the cable and the straight line connecting the two supports.
Catenary Curve  -  The shape of a hanging cable under its own weight forms a catenary curve.  The formula to calculate the actual length of the cable takes this curve into account.
Cable Tension  -  Proper sag and tension are necessary to avoid excessive stress on the cable, which can affect the signal quality.
Environmental Impact  -  Factors like wind, temperature, and load can influence sag, and engineers must account for this when designing cable installations.