This Standard specifies a test method for determining the energy efficiency of magnetic isolating transformers and electronic step-down convertors primarily used or intended to be used with extra-low voltage (ELV) lamps covered in IEC 60357.

The transformers or convertors covered in this Standard have a mains supply input and a single a.c or d.c ELV output. These are referred to as ELV lighting convertors (ELCs) in this Standard.

The ELCs are generally used for Class III luminaires or SELV lighting systems with an output voltage not exceeding 50 V a.c.