The purpose of this part of IEC 61300 is to determine the suitability of a fibre optic device to
withstand the environmental condition of high humidity and change of temperature which may
occur in actual use, storage and/or transport. The test is primarily intended to determine the
suitability of fibre optic components under conditions of high humidity - combined with cyclic
temperature changes and, in general, producing condensation on the surface of the specimen.
Absorption of moisture may result in swelling that would destroy functional utility, cause loss
of physical strength, and cause changes in other important mechanical properties.
Degradation of optical properties may also occur. Although not necessarily intended as a
simulated tropical test, this test can, nevertheless, be useful in determining moisture
absorption of insulating or covering materials.