Exposure to temperatures greater than a wire/cable’s rating can occur for a variety of reasons such as burst air duct, over current, or equipment failure. For well-designed wire/cable systems, the short duration elevated temperature exposure should not impact the insulation integrity. This test is performed to ensure that the wire temperature rating is not at the maximum usable limit.
The life cycle test (also referred to as the ‘Multi-day heat aging test’) seeks to assess short-term elevated temperature exposure to a wire/cable above the sample’s temperature rating.
Note: This test is included as a requirement for many wire types. The procedures below have been generalized.
Perform visual examination of sample and record any defects and/or damage.
Strip the insulation from the ends of the sample and affix a terminal.
Place test sample on test jig with a specified weight hanging on both ends of the sample.
Place test jig into the oven at a specified temperature above the sample's temperature rating (typically 30C above the specification rating) for the specified duration.
Remove the test jig from the oven and allow the sample to return to room temperature.