Low resistance grounding comparison chart Post Glover

Low Resistance Grounding Comparison Chart

Standard Practices For Industrial Plants
Voltage 600 volts and lower 2.4 to 35 kv	Grounding Method Solid Grounding & High-Resistance Grounding Low Resistance Grounding
NOTE: A recent trend on 600-volt and lower systems has been to use high resistance grounding with all the inherent advantages it has to offer.

Comparative Benchmarks for Various Grounding Methods
	Methods of Grounding
Characteristics	Ungrounded	Solid Grounded	Low Resistance	High Resistance
Immunity to transient over-voltages	Worst	Good	Good	Best
Increase in voltage stress under line-to-ground fault conditions	Poor	Best	Good	Poor
Equipment protected against arc fault damage	Worst	Poor	Better	Best
Safety to personal	Worst	Better	Good	Best
Service reliability	Worst	Good	Better	Best
Maintenance cost	Worst	Good	Better	Best
Continued production after first ground fault	Better	Poor	Poor	Best
Ease of locating first ground fault	Worst	Good	Better	Best
Permits designer to coordinate protective devises	Not Possible	Good	Better	Best
Ground fault protection can be added easily	Worst	Good	Better	Best
Two voltage levels on the same system	Not Possible	Best	Not Possible	Not Possible
Reduction in frequency of faults	Worst	Better	Good	Best
First high ground fault current flows over grounding circuit	Best	Worst	Good	Better
Potential flashover to ground	Poor	Worst	Good	Best