60.1.2 Mating attachment plugs with solid blades are to be inserted into the contact openings of three ofthe six devices. The devices are then to be placed into an environmental chamber and subjected to thefollowing conditions:
a) 4 hours at a temperature of 75 ±1°C (167 ±1.8°F) at a relative humidity of 92 ±3 percent.
b) 16 hours at a temperature of 75 ±1°C (167 ±1.8°F) at a relative humidity of 40 ±3 percent.
c) 4 hours at a temperature of 30 ±1°C (86 ±1.8°F) at a relative humidity of 60 ±3 percent.
上述为ul498中Dielectric Voltage-Withstand Test的语句。我想请问是测试时是a)b)c)都要做,还是任意满足其中的一个条件就可用。即如何理解“the following conditions”