UL 5085-1:2018 PDF Download

The UL 5085-1:2018 standard encompasses various types of transformers. These include air-cooled transformers and reactors for general use, general purpose autotransformers, ferroresonant transformers, Class 2 and Class 3 transformers, cord-connected transformers, transformers incorporating protective devices or capacitors, and permanently-connected transformers.

These transformers are intended to be used in compliance with the National Electrical Code (ANSI/NFPA 70) or the Canadian Electrical Code, Part I (CSA C22.1). The definition of low voltage varies between the two codes, with the Canadian Electrical Code considering any voltage from 31 to 750 V as low voltage, while the National Electrical Code defines low voltage as up to 600 V. Therefore, transformers intended for use in Canada may have a rating above 600 V but up to 750 V, while transformers used in the United States are rated up to 600 V.

However, there are certain transformers that are not covered by this standard. These include direct plug-in types, neon transformers, liquid-immersed transformers, variable voltage (Variac) transformers, low voltage landscape transformers, swimming pool and spa transformers, ignition transformers, high-intensity lighting transformers, toy transformers, fluorescent lamp transformers, transformers for welders, distribution transformers, transformers with a primary rating of more than 600 V in the United States, transformers incorporating rectifying or waveshaping circuitry, transformers for use with radio- and television-type appliances, transformers in the United States with overvoltage taps rated over 660 V, autotransformers used in industrial control equipment, and other special types of transformers covered in requirements for other electrical devices or appliances.

The standard consists of three parts (Part 1, Part 2, and Part 3), each establishing the characteristics, construction, operating conditions, markings, and test conditions for a specific type of transformer. Additionally, if a transformer is intended to be used solely as a component in other equipment, the requirements in this standard may be modified by the requirements of an end product standard.