This part of IEC 61300 details a procedure to determine the suitability of a fibre optic interconnecting device, passive component, splices or closure to withstand the environmental condition of extended high temperature that occur during operation, storage and/or transport. The test is intended to indicate the performance of such devices when exposed to heat of constant temperature over a given period. In general terms, this test provides a high temperature to induce potential failures due to softening and expansions. This procedure does not assess the ability of a device to operate during temperature variations; in this case, IEC 61300-2-22 is used.