An overhead line has the following data: Span length 185 metres. Difference in levels of supports 6.5 metres, conductor dia 1.82 cm, weight per unit length of conductor 2.5 kg/metre, wind pressure 49 kg/m2 of projected area. Maximum tensile stress of the conductor 4250 kg/cm2. Factor of safety 5. Calculate the allowable sag in metres at the lower support.