UL 879A-2012 pdf download – LED Sign and Sign Retrofit Kits.
5 Glossary 5.1 CLASS 2 CIRCUIT – The wiring, conductors and components connected only to a Class 2 supply source. See Class 2 Supply Source, 5.2. 5.2 CLASS 2 SUPPLY SOURCE – An electrical source, such as a transformer, power supply, or battery, having an open-circuit voltage that is less than 30 Vrms (42.4 Vpeak) or 60 Vdc and having limited energy available in the circuit under load conditions, including short-circuit and extremely low resistance. A Class 2 supply source can be either inherently limited or non-inherently limited. a) INHERENTLY LIMITED SUPPLY SOURCE – A transformer, power supply or battery having no discrete protective device that is relied upon to limit the output energy available from the supply. A power supply or battery with internal current and energy limiting circuitry shown to be reliable is eligible to be identified as inherently limited. Transformers, power supplies and batteries may be provided with protective devices as long as they are not relied upon to limit the output. b) NON-INHERENTLY LIMITED SUPPLY SOURCE – A transformer, power supply or battery having a discrete protective device that automatically interrupts the output when the current and energy output reaches a prescribed limit. 5.3 CONDITIONS OF USE – Parameters and specifications that identify the proper use of a component according to the requirements to which it has been determined to comply, and limitations of the use of the component in a sign or outline lighting.
5.4 DAMP LOCATION – The designation for a component that has been evaluated generally for use in exterior locations where protected overhead from rain and snow, or interior locations where subject to moderate degrees of moisture, primarily by humidity and condensation. Protected overhead is generally considered to be within an area formed by an imaginary line drawn from the outer edge of the eave, overhang, or signbody inward at a 45° angle from vertical. Additionally, the interior of a sign body provided with a sign face and installed in an outdoor exposed location is a damp location. Examples include partially protected areas such as under a canopy, under a roofed porch, or indoors in a car wash away from a direct water spray. 5.5 DRY LOCATION – The designation for a component that has been evaluated for use in an environment where the component is not normally subject to dampness or wetness. Examples include inside an indoor shopping mall, inside a retail store, in an attic or scuttle, and other similar places. 5.6 ELV CIRCUIT – A secondary circuit with limited voltage and energy that reduces the risk of fire and shock in accordance with the requirements in the Standard for Information Technology Equipment Safety – Part 1 : General Requirements, UL 60950-1 .