These requirements cover electrical resistance trace heating for commercial and applications as applied to piping@ vessels@ traced tube bundles@ and mechanical equipment. Trace heating includes heating cables@ heating panels@ and associated parts. This equipment is intended for installation in ordinary locations in accordance with the the following installation guidelines: National Electrical Code@ ANSI/NFPA 70@ Article 427 IEEE Standard for the Testing@ Design@ Installation@ and Maintenance of Electrical Resistance Trace Heating for Commercial Applications@ IEEE 515.1. These requirements also cover commercial applications of electrical resistance trace heating for deicing roofs@ gutters@ and pavement. This equipment is intended for installation in ordinary locations in accordance with the following installation guidelines: a) National Electrical Code@ ANSI/NFPA 70@ Article 426; and b) IEEE Standard for the Testing@ Design@ Installation@ and Maintenance of Electrical Resistance Trace Heating for Commercial Applications@ IEEE 515.1. Trace heating covered by this Standard is intended for applications where it is exposed to weather@ unless specific markings and instructions limit the applications Trace heating may be installed on metal or rigid plastic pipes. Unless specific recommendations are made for the plastic pipe material to be heated@ plastic pipes are considered to have a maximum long-term thermal exposure limit of 50??(122?? Other related equipment standards: a) For Embedded Floor Warming Applications@ refer to the Standard for Electric Space Heating Cables@ UL 1673. b) For Mobile Home Pipe Heating Cables@ refer to the Outline of Investigation@ UL 1462. c) For Residential Pipe Heating Cables@ refer to the Outline of Investigation@ UL 2049. d) For Roof and Gutter De-Icing Cable Units@ refer to the Outline of Investigation@ UL 1588. This Standard does not cover electrical resistance trace heating for industrial applications such as chemical plants@ pipelines@ refineries@ and other similar locations where the trace heating is expected to be installed by qualified personnel.