Low resistance grounding systems limit the fault current when a phase of a power system unintentionally goes to ground. The majority of systems limit the fault current to 200-400 amps in the USA, based on the guidelines contained in IEEE-142. When a fault occurs, the neutral grounding resistor (NGR) limits the current that can flow from ground back to the transformer. This limits the fault current on grounds throughout the entire system. Although limited, the current is still high enough to require protective relays to trip a breaker and remove power from the faulted system.

• NGRs are available from 480 volts to 72kv (line-line voltage).
• Initial Currents from 50 to 2,000A
• The standard NGR comes complete with an outdoor enclosure (galvanized or painted) for mounting on top of or next to a power transformer or generator.
• Numerous options are available ranging from CT's, disconnect switches, elevating stands, stainless steel or aluminum enclosures, and grounding.