Heating elements of the tubular form are filled with a very fine powder that can absorb moisture if the element has not be used for some time. In the tropics, this may occur, for example if a clothes drier has not been used for a year or a large water boiler used for coffee, etc. has been in storage. In such cases, if the unit is allowed to power up without RCD protection then it will normally dry out and successfully pass inspection. This type of problem can be seen even with brand new equipment.