Conductor Pulling Tension
Capstan-equation pulling tension and sidewall pressure across bends.
Example
You enter
- Cable weight (lb/ft) 1.5
- Total run length (ft) 200
- Lubricant polymer
- Straight run before bends (ft) 100
- Bends angle (deg) 90, radius (ft) 2
You get
- Head-end tension 71 lb
- Max sidewall pressure 21 lb/ft
- Status ok
- Sidewall flag ok
Checked against published worked examples from: NECA / cable-pulling engineering practice.
Details, formula, and sources
Formula or tableCapstan equation T_out = T_in × exp(μ × θ) accumulated per bend; sidewall pressure T/R per bend; flagged against 5000 lb head-end / 1000 lb-per-ft sidewall thresholds.
Source and editionManufacturer pull-tension guides (Southwire, Encore Wire) by name.
Free accessFree at southwire.com and encorewire.com technical bulletins.
What governsEstimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
API field namescable_weight_lb_per_ft, run_length_ft, lubricant, straight_run_ft, bends, tension_lb, max_sidewall_lb_per_ft, tension_flag, sidewall_flag
- Coefficient of friction 0.5 unlubricated / 0.2 lubricated unless user suppliesmanufacturer pull-tension guide typical