ABSTRACT
Codes constantly are being changed or expanded, because new situations arise that were not anticipated when the codes were written. Sometimes, an interpretation will depend on whether the governing safety standard applies to building wiring or to a factory-assembled product to be installed in a building. Underwriters Laboratories (UL) and other qualified testing organizations examine products at the request and expense of manufacturers or purchasers. They “list” products if the examination reveals that the device or system presents no significant safety hazard when installed and used properly.
