Guy-Wire / Down-Guy Tension and Mast Download

The tension in a guy wire holding a mast, pole, or tower against a horizontal load, and the vertical compression it stacks onto the mast. A down-guy attached at height H_a and anchored a lead L away sits at theta = atan(H_a/L) above horizontal. To resist a horizontal top load H (wind, a conductor pull, a sign's wind area) the guy carries H / cos(theta) -- always MORE than the load, climbing steeply as the guy steepens -- and pulls DOWN on the mast by H x tan(theta) (the mast download the pole and footing must carry) and UP on the anchor by the same. A 500 lb load, 20 ft up, 20 ft out sits at 45 deg: 707 lb tension, 500 lb download. A guy at 63 deg more than triples the download -- why crews want long anchor leads. Single-guy statics only; the pole class, anchor capacity, guy grade, and the engineer / NESC / RUS govern.

theta = atan(attachment_height_ft / anchor_lead_ft); guy_tension_lb = horizontal_load_lb / cos(theta); mast_download_lb = horizontal_load_lb x tan(theta); anchor_uplift_lb = mast_download_lb.

Guy-wire / down-guy tension and mast download (engineering statics; for utility work NESC and RUS Bulletin 1724E), by name; the pole class, the anchor holding capacity, the guy grade, and the engineer of record govern.

The guy-tension relation is public statics (resolve the horizontal load along the guy and the mast); the load, attachment height, and anchor lead are the installation's geometry.

Estimate. AHJ and licensed professional govern.

Field names used by the API: horizontal_load_lb, attachment_height_ft, anchor_lead_ft, guy_angle_deg, guy_tension_lb, mast_download_lb

• Guy statics theta = atan(height/lead); tension = H/cos(theta) (always > H); mast download = anchor uplift = H x tan(theta)engineering statics
• Single-guy screen one guy vs a horizontal top load; a real rig balances multiple guys, mast wind/weight, and pretension; the pole class, anchor capacity, and NESC/RUS governNESC / RUS Bulletin 1724E