A Victorian company’s appliance testing regime only found an incorrectly designed earth circuit in a large number of appliances after switching from Screen testing (100mA-200mA) to Bond testing (25A).
This affected hundreds of appliances within the company. They were fortunate that none of them had become faulty before the change in practise.
The manufacturer was notified and the products recalled for modification to provide an effective earth circuit to ensure their safety.
The Earth Bond test is able to confirm if the earthing circuit is capable of safely carrying a short circuit current. At 25A, it will strain an Earth cable that has many broken strands and will fail the circuit if it has only one or two strands remaining.