Electric wiring

In safety evaluations of products the leakage current testing is only conducted on cord connected products due to the following reasons:

Cord connected products are likely to have a higher failure rate of the grounding system, or circumvention of the grounding lead. This may be due to normal use as the appliance is moved around, the cord is flexed, and the plug is repeatedly inserted and removed from the socket during use.

Corded products, particularly powered hand tools are more often in contact with the operator, so they are a greater shock hazard .

These products tend to see more abuse (dropping, etc.) than something that's positioned in a fixed manner.

A fixed installation usually has more than one path to ground available. While a single grounding lead is essential, the conduit also provides a grounding path.