Method of Grounding |
Condition
or
Characteristic |
Ungrounded |
Solid
Ground |
Low
Resistance |
High
Resistance |
 |
Immunity
to translent
Overvoltages |
Worst |
Good |
Good |
Best |
|
Ground
Fault Protection
Can Be Added Easily |
Worst |
Good |
Better |
Best |
|
| Equipment
Protected Against Arc Fault Damage |
Worst |
Poor |
Better |
Best |
|
| Safety
to Personnel |
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 |
|
| Relay
Co-ordination |
Not
Possible |
Good |
Better |
Best |
|
73%
Increase in Voltage
Stress Under
Line To Ground
Fault Conditions |
Poor |
Best |
Good |
Poor |
|
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
|
Worst |
Better |
Good |
Best |
|
Potential
Flashover
To Ground
|
Poor |
Worst |
Good |
Best |
| |
Download
a pdf of the comparison rating chart.
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