The Neutral Grounding Resistors are generally employed in the LV and MV distribution networks to protect power transformers and generators from damaging currents in the event of earth fault. This protection system represents the best choice in terms of fast response to localize the fault and consequently to reduce and prevent the overheating and mechanical stress on the conductors. By inserting the N.G.R with appropriate characteristics between the neutral point of the transformer and the ground it is possible to limit the ground fault current for a short time to allow a quick localization of the fault but, at the same time, it does not damage the equipments. Many optional features/equipments can be associated with the neutral grounding resistor -Terminal box for I/O cables -Terminal box for additional devices -Zigzag grounding transformer, dry type, air cooled -Three phase transformer Wye/Delta type -Current and/or voltage transformers -Load-break or load-less load switches -Vacuum contactors -Surge arrestor -Space heater