Jim Stafford sez: *****The following example is not great but maybe somebody else can think of something bettter. Lets say there is clock installed on the wall with a removeable power cord. Its only purpose is for visual indication of the time. It has been constructed and installed according to the NEC provisions. Why does a NRTL need to approve it?. The installation will still need to be inspected by a local authority to determine if it was installed properly. Hmmmm******
The answer is that the NEC does NOT say how how to construct and install the device. What the NEC says, in Art.110, is that you must install and use the device in accordance with its listing! The implication here is that the NEC is leaving Standards up to the Standards people and NRTLs. There are a few minimum construction criteria here and there , e.g., which types of appliances must be grounded. But you would never find enough criteria to build a safe electric clock. Keith Gershon Electrical Safety Engineer LBNL [email protected]
