Defective designs of new kettles can take too long to switch off. After a short period of use, this time can lengthen and eventually they do not switch off.
Causes of failure to switch off:
Failure to switch on is less common in early life, but can occur if mains plugs are not wired correctly, excessive scale builds up on elements that is not removed by users or due to poor control installation.
A high rate of early switch mechanism failures (<12 months) can occur if these are poorly designed or of sub-standard quality.
Kettle controls and connectors are supplied to kettle manufacturers as separate components. These parts include the electric contacts that connect mains power to the heating elements. The lifetime of the parts can be shortened due to:
The specification below provides the recommended improvements needed to improve product durability. They are ranked from bronze to gold, based on the effectiveness of the change in improving durability, with bronze being the minimum.
Only use tested controls that survive required number of cycles
Ensure that switch controls will function for the required number of use cycles by fully testing all new kettle designs to ensure durability. A kettle failure rate of <3% is achievable. Beware of counterfeit controls and copies as these are likely to be unreliable.
Kettle testing as described for lids will also test kettle controls. The test used is fill / boil / empty with lid opening and closing and this is carried out on the required number of cycles for kettles. Descale as necessary during test.