Why isn leakage current a concern on fixed wiring products vs cord connected products?
Cord connected products are likely to be suspect to a higher failure rate of the grounding system, or circumvention of the grounding lead. This can be through normal use as the appliance is moved around, the cord is flexed, and the plug is repeatedly inserted and removed from the socket through its service life. Secondly, corded products, particularly powered hand tools are more often in contact with the operator, so they present a greater a shock hazard in that respect. Third, corded products tend to see more abuse (dropping, etc.) than something that’s positioned in a fixed manner. Fourth, 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. This makes checking the ground path a little more involved as it could be achieving an earth ground through several or more paths, one of which should be the grounding wire.
