Method 4.7.14 is a low pressure test at maximum rated temperature for flat power cables. Unless otherwise specified, the specimen length shall be 26 +/- 0.062 inches (660 +/- 1.6 mm). When a different specimen length is used, the insulation resistance and dielectric withstanding voltage results shall be proportional to the specimen length.
The specimen is prepared by cutting both ends approximately square and weighed on an analytical balance. The test evaluates cable performance under reduced atmospheric pressure combined with elevated temperature.
This test is critical for verifying that flat power cables used in military aircraft and high-altitude applications maintain their electrical insulation properties when subjected to the combined stress of low pressure and high temperature.