Hi,  you can fiind all the data you need in the text Wood Handbook - Wood as an Engineering Material,

http://www.woodweb.com/Resources/wood_eng_handbook/wood_handbook_fpl_2010.pdf

or

http://www.esf.edu/wus/documents/WoodHandbook-fplgtr113.pdf

particularly in the chapters 4-2 (MOE), 4-3 (MOR), and 10 (different kinds of wood panel). 

Best regards.

Togni

http://www.woodweb.com/Resources/wood_eng_handbook/wood_handbook_fpl_2010.pdf

http://www.esf.edu/wus/documents/WoodHandbook-fplgtr113.pdf

Dear Marco,

Thank you for your help and the attachment. It's helpful.

If you would like to know what is the maximum span for your overhead line from the standard formula of Sag:

S= (W1L^2)/8T1

now here first identify the allowable sag as your clearance required example for our OHL maximum sag 3 m

Now you can identify the max span T1 initial tension as your conductor RTS for example 28000 in N and your conductor weight 5 in N/m now apply these values to the formula below:

L= √((8 S T1)/W1)

L = 129.6 m