Bend radius – armoured cables: Bend radius is a key consideration, particularly for armoured cables and for higher voltages of 11kV or more. Minimum bend radius is generally defined by cable standards, or is advisory; it should be communicated by manufacturers and passed on by suppliers to the installers. Sometimes two figures are used; a dynamic radius for the pull, and a possibly smaller final static radius for when the cable is no longer under tension.
Maximum cable tension and sidewall pressure limits can both cause damage if exceeded when pulling cables. To prevent this, cable installation routing should be closely assessed, and several rollers or guides used at any bend points. A single roller or guide’s external radius is always likely to be much lower than the cable’s minimum bend radius. As a simple rule of thumb, for a four-core armoured cable larger than 40mm OD, a full-sized bicycle wheel should fit within the bend.