The model regulation is a supplement to the UN Environment United for Efficiency (U4E) Transformers Policy Guide “Accelerating the Global Adoption of Energy-Efficient Transformers.” It is intended for use by regulatory authorities in developing and emerging economies with 50 – 60 Hz power systems that are considering a legislative framework to promote energy-efficient transformers, or those that have a legislative framework but have not yet developed regulations for energy-efficient transformers.