What coefficient of friction should I use when calculating pulling tensions for SIMpull THHN?
When installing SIMpull THHN, Southwire recommends the same COF used to evaluate standard lubricated THHN installations. The specially designed pre-lubricated SIMpull THHN product has a COF as low as 0.17 when following best installation practices. This has proved to be true through miles of cable pulling tests. Recommended practice for calculation pulling tensions is to begin with a conservative coefficient of friction such as 0.35. This will provide some safety factor for any debris in the conduit or other unexpected field conditions. Southwire’s application engineers utilize a 0.35 COF when evaluating cable pulls. This conservative approach is a result of not having the ability to evaluate the condition of the conduit in the field.
