Cold Elongation Testing is conducted to meet the requirements of BS EN 60811-505. It is performed on the insulation and sheathing materials of electrical cables and fibre optic cables with a diameter in excess of 12.5mm. Cables of a smaller diameter are more commonly subject to the Cold Bend Test to IEC 60811-504.
From the prepared sample of cable insulation (thickness between 0.6mm and 2mm) and which has been conditioned at ambient room temperature, 2 dumb-bell shaped test samples are punched vertically in the material; ideally these test samples should come from side-by-side.
These test samples are then placed in a pre-cooled cooling chamber. They are fixed to the tensile and elongation apparatus with clamps at the top and bottom, leaving 30mm of sample between them. They are then left to condition for 2 hours. Once conditioned, the clamps then pull in opposite directions at a speed of 25mm/min, elongating the test samples until the point of break.
The elongation is determined by measuring the distance from start point to point of rupture. To achieve a pass in this test, the elongation must have achieved a minimum 20% increase on the original test sample size before breaking.