The flexibility of a wire/cable is dependent on a combination of the conductor and insulation constructions. Wire/ cable constructions with more conductor strands are often better able to endure flexing without breaking whereas more rigid constructions are more likely to crack or break over periods of excess mechanical stress. The flexibility of a wire or cable plays a significant role in its longevity and maintainability.
There are two methods covered by the EN3475 flexibility test, the appropriate method is determined based on the size of the cable under test.
Method 1 is applied for cables larger than 10 AWG. A length of the cable is formed into a single loop with diameter 40 times that of the diameter of the cable. The loop shape is maintained either by solder or spliced. The loop is then compressed via a compression force tester at a constant rate to a defined height and the compression force is reported.
Method 2 is applied for cable sizes up to 10 AWG. The cable specimens are straightened either by hand or by a 24hr vertical oven exposure. Each specimen is fitted to the test fixture in which weight is gradually applied to bend the sample 90 degrees over a mandrel. The specimen is held in the bent position for 5 minutes then released and allowed to recoil. The weight applied and the distance of recoil are reported.