Reduction of wind load due to angle to line 1

[gwillis33]

NESC 252B.3 says wind load on a line should be reduced due to the angle of wind to line. sag10 has no provision for allowing for angle of wind to line. It is something to be concerned about? Thanks.

 

[jghrist]

Sag-tension calculations generally are for multiple spans between deadends. You could only account for the angle to the wind if you had only two spans between deadends and an angle in between. Don't be concerned with sag-tension calculations.

 

[gwillis33]

jghrist, thanks for your comments. It is not only when there is a deviation at a pole. If the spans lengths are not the same, even if the tension is, the worst case pole load will probably not occur when the wind is perpendicular to the line. Other software such as Poles 'n' Wires makes allowance for any wind directions and calculates the worst case pole load. But I am using sag10 and there is no provision for that. I was hoping another sag10 user had a suggestion about how to handle it.

 

[bacon4life]

You have to use a bit of trigonometry to calculated the reduced equivalent wind for inputting into SAG10. Previous versions of the NESC used may rather than should. Prior to our line designers acquiring PLS-CADD, it was usually a better use of engineering time to just assume full loading rather than try to calculate the maximum loading angle and then use the allowable reductions.

Welcome to eng-tips. Please post in only one forum as many of us read several areas. Red flagging thread507-407801 will keep all of the responses in this thread.

 

[gwillis33]

I should have been more careful in my reference - NESC 2012 does use the word may not should in rule 252B.3.